Research Article Manner of Apical Meristem Destruction ...

Research ArticleManner of Apical Meristem Destruction Affects GrowthReproduction and Survival of Sea Oxeye Daisy

Lisa S Spirko and Anthony M Rossi

Department of Biology University of North Florida 1 UNF Drive Jacksonville FL 32224 USA

Correspondence should be addressed to Anthony M Rossi arossiunfedu

Received 22 May 2015 Accepted 1 September 2015

Academic Editor Zed Rengel

Copyright copy 2015 L S Spirko and A M Rossi This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

Although herbivory may result in plant death the mode and timing of damage may produce variable wounding responses inthe attacked plant In this study effects of different types of apical meristem damage on growth and performance of sea oxeyedaisy Borrichia frutescens (L) DC were compared Damage involved either clipping or galling of the apical meristem by thegall midge Asphondylia borrichiae Rossi and Strong Apical dominance was relatively weak before flowering and stronger inshort ramets that were shaded by taller neighbors later in the season Clipped ramets delayed sprouting new stems and galledramets sprouted new stems quickly compared to intact ramets but final stem counts were similar across treatments Clippingsignificantly delayed flowering reduced seed head ripening time and resulted in fewer seed heads and seeds Galling did notsignificantly impact reproduction compared to intact ramets Nitrogen supplementation significantly increased stem count and seedcount and lengthened seed ripening time Borrichia frutescens responds differently to clipping versus galling by A borrichiae andbetter tolerates galling in terms of nonreproductive performance and survival Galling from A borrichiae likely prevents Borrichiafrutescens from flowering which suggests resource regulation of meristems by the midge

1 Introduction

Plant-animal interactions such as herbivory and parasitismcan vary greatly in their effect on plants ranging from deathand decreased plant performance and fitness at one end ofthe spectrum [1 2] to resistance (eg chemical or physicaldefenses) and tolerance or compensatory regrowth at theother end [3ndash12] Many of these relationships have existedfor long periods and coevolution or the extent to whichspecies are closely adapted (ie coadapted) to each other haslong been understood as the driver by which mechanisms ofresistance [13 14] and tolerance [9 14 15] develop

Tolerance arises from the complex interactions of numer-ous genetic physiological and morphological traits includ-ing plant architecture [5 8] meristem allocation [7 8 10 1115] nutrient uptake [15] photosynthetic rates [8 15] and phe-nological timing [3 15ndash17] under influence of environmentalfactors [10 11 15] For example plant species that hold axillarybuds dormant may regain lost tissue if the apical meristemor actively growing stem tip is damaged because it disrupts

apical dominance or hormonal suppression of axillary budsby the apical meristem and allows new growth [3ndash7 9ndash11] Insome cases overcompensation or regrowth that exceeds theamount of tissue lost and even results in improved fecundityhas been documented [3 18ndash21] The degree of tolerance orcompensation is often subject to such environmental factorsas the timing of herbivory or parasitism (ie the seasonin relation to the plantrsquos phenological state) and nutrientavailability For instance Ipomopsis aggregata significantlyincreased its flowering stems after browsing early in the grow-ing season by ungulates [3] In another study [16]Gentianellacampestris overcompensated in terms of fruits and seeds butonly when simulated herbivory (clipping) occurred during anarrow window in Swedenrsquos growing season Benner [17] alsofound overcompensation in transplants of Thlaspi arvenseoccurred if nutrient supplementation was provided early inthe growing season

Apical meristem damage also may occur as a resultof cecidogenesis (gall-making) which involves a uniqueintimate relationship between the gall-inducer typically an

Hindawi Publishing CorporationJournal of BotanyVolume 2015 Article ID 480891 11 pageshttpdxdoiorg1011552015480891

2 Journal of Botany

insect or fungus and its host plant and results in a tumor-likeovergrowth of plant tissue [22ndash28] Gall-inducers tend to bespecialists and highly specific to their particular host speciesgenus or family and to the organ they attack suggesting tightcoevolutionary relationships in these systems [22 23 28 29]Gagne [28] reports that gall midges (Cecidomyiidae) are usu-ally monophagous (one host plant species) or oligophagous(a few closely related species) In a review of the literaturespanning 196 neotropical species of gall midges Carneiroet al [30] found that 924 were monophagous and 56were oligophagous Additionally 908 of the cecidomyiidspecies reviewed were found to induce galls on only oneplant organ (leaves flowers or stems) further supportingthe claim that they are host specialists Galling of the apicalmeristem can disrupt apical dominance and initiate axillaryshoots [27 31 32] Thus since host plants likely coadaptedwith their associated gall inducers it is reasonable that plantsattacked by apical gall inducersmay demonstrate tolerance orcompensation in response to the damage

Galls of the midge Asphondylia borrichiae on the apicalmeristem of sea oxeye daisy (Borrichia frutescens) are associ-ated with stem bifurcation below the gall [33] Other types ofnaturally occurring apicalmeristemdamage such as chewingby grasshoppers (egOrchelimumfidicinium) are seen rarelyin the field (Anthony M Rossi personal observation)

The overall goal of this research was to examine thecompensatory response of B frutescens to different types ofapical meristem damage in young single-stemmed rametsDamage to the meristem was either sudden (ie clippingto simulate chewing) or gradual via galling which slowlydestroyed the apical meristem Because the plantrsquos ability tocompensate depends largely on having a bank of dormantbuds in reserve [3ndash5 10 11 34] the strength of apicaldominance in B frutescens was investigated in relation toits response to meristem damage A second experimentinvestigated how B frutescens responds to clipping galling byA borrichiae and nutritional differences in terms of growthand reproduction (ie flower head and seed production)

2 Materials and Methods

21 Study System Borrichia frutescens commonly known assea oxeye daisy or bushy seaside tansy is an herbaceoushalophytic perennial shrub found in salt marshes along theUS Atlantic andGulf ofMexico coasts [35] It propagates pri-marily through extensive rhizomes [36ndash38] but also producessmall monoecious flower heads consisting of 15ndash30 petal-likeray florets and 20ndash75 disc florets per flower head [35ndash39]Each floret produces an achene or dry seed-bearing fruit andeach achene contains a single seed Peak flowering is betweenMay and July [38] and flowering rates or the number offlower heads per ramet range from 3 to over 20 (althoughthese rates can be much higher) depending on factors suchas season or access to tidal inundations of nutrients [4041] Under greenhouse conditions seed viability of 90 wasreported by Biber et al [39]

Borrichia frutescens is the primary host plant of the gallmidgeAsphondylia borrichiae [33 41ndash43] AdultA borrichiae

are small (lt3mm long) fragile weak-flying gall midges thatlive for only 2-3 days during which their primary activity isbreeding [2 44ndash46] Female A borrichiae collect the conidiaof a fungal symbiont and deposit the conidia with her eggsinside the apical meristematic tissue of the host plant duringoviposition which induces a gall to form [42 45 47 48]Larvae feed on the fungal symbiont which draws nutrientsfrom plant tissues and they pupate within the gall [47 48]With occasional exceptions female midges appear to avoidovipositing in flower heads [40 42] and the presence of agall typically prevents the apical meristems from flowering[33 42 45] Galls persist on the host plant during springand summer for about seven to ten weeks and senesce aftermidge eclosion typically resulting in the death of the galledapical meristem [33 45] A previous study at the site in2005 found moderate correlation between stem count andgall count (AnthonyM Rossi unpublished data) Aside fromgalling byA borrichiae the sap feeding leafhopper Pissonotusquadripustulatus and the aphid Dactynotus sp are the onlyother herbivores regularly associated with B frutescens inFlorida [49ndash51]

22 Field Site This study was conducted at Timucuan Eco-logical and Historic Preserve in Jacksonville Florida USA(N30∘2210158404510158401015840 W81∘2810158404910158401015840) This site features an intertidalback-marsh community bordered by hammock and consist-ing primarily of Borrichia frutescens Previous studies at thissite [43 47] have found galling onB frutescens to be very high(approximately 30ndash50 of apical meristems) and a strongpositive correlation between stem number and gall count(Anthony M Rossi unpublished data)

23 First Bud Break Experiment To investigate the strengthof apical dominance in B frutescens and to test its response tovarious types of apical meristem damage 25 single-stemmedB frutescens ramets (ie individual plants) were randomlyassigned to a stem treatment in May 2013 (1) galled (2)clipped or (3) intact Ramets in the galled group began theexperiment with a single stem but also had a single live gall(ie green no emergence holes) Clipping was performedby removing the apical meristem and the terminal pair ofleaves with scissors (removing approximately 1 cmof the stemtip) Intact ramets were protected from galling by a mesh bagplaced over the apical meristem and secured with a twist tieTwo-way ANOVA on light readings (Basic Quantum Metermodel BQM-SUN Apogee Instruments Inc Logan UtahUSA) taken inside and outside the mesh bags in sunny andshady conditions revealed no effect of the mesh bags or theirinteraction with light conditions on light penetration (insideversus outside mesh 119865

139= 0004 119875 = 0949 sunny versus

shady 119865139= 3277478 119875 lt 0001 mesh times light 119865

139=

0022 119875 = 0882) Ramets were monitored for bud breakbiweekly and after eight weeks the node number bearingthe bud to break first was recorded (0 = apical meristemor clipped stem tip 1 = first node below apical meristemetc) and its distance measured from the apical meristem orclipped stem tip (nearest 01 cm) Differences in the numberof surviving ramets that broke bud at eight weeks were

Journal of Botany 3

tested using a 1205942 test One-way ANOVA was used to test thenumber of days and distance to first bud break Variancesof time data were homogeneous but due to small samplesizes of surviving ramets normality was inferred based on alinear probability plot of residuals Distance datawere square-root transformed to achieve normality and homogeneity ofvariances After a significant main effect group means wereanalyzed with Tukeyrsquos HSD test to examine planned pairwisecomparisons between treatments The ratio of ramets withdifferent frequencies of nodes bearing bud break was testedusing 1205942 test Due to low sample sizes frequencies for nodestwo and more distal from the apical meristem were pooledand the1205942 test compared nodes 0 1 and 2+ across treatments

24 Stem Condition and Nutritional Status Experiment Totest the effects of apical meristem damage on regrowthseed set quality and viability and any interaction with plantnutritional status (ie nitrogen levels) a 3 times 2 fully factorialexperiment involving three stem treatments (galled clippedand intact) and two nutrient treatments (fertilized and notfertilized) was initiated in January about 11 weeks before theflowering season started For this experiment approximately300 single-stemmed Borrichia frutescens were selected hap-hazardly and assigned randomly to one of six groups (1)galled and fertilized (2) galled and not fertilized (3) clippedand fertilized (4) clipped and not fertilized (5) stem intactand fertilized and (6) stem intact and not fertilized (control)Each of the previous treatments began the experimentwith 50ramets (ie individual plants) Ramets in the galled groupsbegan the experiment with a single stem and gall Clippedramets were clipped once at the beginning of the experimentIntact ramets were left unprotected from galling Howevermany intact ramets were expected to be galled during theexperiment [43 47] and may have severely reduced thesample size of the control group Therefore in additionto the first control group of 50 ramets a second controlgroup of 20 additional intact unfertilized ramets was selectedhaphazardly and protected from galling by a mesh bag Afterexperiment completion all statistical analyses were first con-ducted on the bagged and unbagged control groups only andfinding no significant differences between them data werepooled into a single control group for all remaining analyses

Ramets in the three fertilized treatment groups receiveda small amount (ca 2 g) of supplemental nitrogen in theform of blood meal (N-P-K 12-0-0 Miracle-Gro OrganicChoice BloodMeal ScottsMiracle-Gro ProductsMarysvilleOhio USA) every four weeks The blood meal was appliedby carefully forming a hole approximately 3-4 cm deep or asallowed by the soil compactedwith oyster shells near the baseof the ramet using a screwdriver pouring the bloodmeal intothe hole and covering it with substrate Effects of the holewere controlled in the nonfertilized groups by creating a holeand then filling it in

Total stem counts (ie main stem and axillary stems) andthe presence of flower head buds on ramets were assessedevery two weeks from January through June 2013 Stems werecounted if they were alive and at least one centimeter longFlower head buds were tagged at first appearance through

the end of June and were monitored biweekly until seedhead harvesting which concluded in early September withthe initiation date of each phenological event (ie buddingblooming and ripening) and harvesting recorded After eachflower head finished blooming (ie all florets had senescedandor abscised) a mesh bag was placed over them andseed heads were harvested when they were brown and dryand the stalk was senescent Each seed head was carefullybroken apart and each ldquoseedrdquo (achene or dry seed-bearingfruit) separated from its bract with forceps Seeds that wereabnormally developed (shriveledmalformed) were removedNormal seeds were counted and weighed to the nearest10minus4mg

Germination success of the normally developed seedsproduced was determined in September after all seed headshad been harvested and processed abnormally developedseeds were excluded from the germination phase of theexperiment Twenty-five seeds or fewer if less than 25 seedsdeveloped were randomly selected from each seed headand soaked for 48ndash60 hours in tap water [39] All seedsfor each seed head were planted together in the cell of ahorticultural flat or a seedling pot in a 1 1 blend of AceHorticultural Grade Vermiculite (A H Hoffman Inc Lan-disville Pennsylvania USA) and Organic Seed Starting Jiffy-Mix (Ferry-Morse Seed Company Fulton Kentucky USA)the latter which contained 48ndash52 sphagnum peat moss48ndash52 vermiculite lime and an organic wetting agentNo fertilizers were included in the original manufacturedproducts or added to the final planting mixture Seeds werevery lightly covered with planting medium placed in lightshade in a greenhouse (asymp25ndash30∘C asymp60 relative humidity)and lightly watered under timed misters for four minutesevery four hours for 12 weeks Because unequal numbers ofseed heads were produced in each treatment a Latin squarelayout was not possible Treatments were randomized acrossrows and columns as possible

Except where noted all statistical analyses were con-ducted on ramets surviving to the end of the experiment andon intact ramets remaining intact (ungalled) until the end ofthe experiment Mean (plusmnSD) overall survivorship across alltreatments at the end of the experiment was 766 plusmn 09 andranged from a low of 742 for clipped ramets to a high of788 for intact ramets These differences were not signifi-cantly different across treatments (stem 1205942 = 0629 119889119891 =2 and 119875 = 0730 fertilizer 1205942 = 0357 119889119891 = 1 and119875 = 0550) therefore statistical analyses of counts could beperformed with the assumption that the number of survivingramets was similar across treatments Stem counts at the endof the experiment were found to follow a Poisson distributionbecause ramets began the experiment with a single stem andthe experiment was conducted over a relatively short periodof time (25 weeks) Thus stem counts were not parametricand were tested across stem treatments and fertilizationtreatments using Kruskal-Wallis tests Chi-square (1205942) testswere used to test the number of ramets that produced flowerhead buds and the total number of seed heads producedacross treatments The number of days to first floweringor the number of days between the start of the experimentand the day the first flower head bud on each flowering

4 Journal of Botany

Galled Clipped Intact

AA

B

0

20

40

60

80

100

120

Aver

age n

umbe

r of d

ays

P lt 0001

(a)

Galled Clipped Intact0

20

40

60

80

100

Bud

brea

k (

)

P lt 0001n = 1010 n = 1515

n = 021

(b)

Figure 1 In the first bud break experiment (a) average number of days to first bud break with SEM error bars across stem treatments(119865224

= 45568 119875 lt 0001) and (b) percent bud break occurring by eight weeks across stem treatments (1205942 = 46000 119889119891 = 2 and119875 lt 0001)Different letters in (a) indicate significant differences among treatments (Tukeyrsquos post hoc with Bonferroni correction to 120572 = 0017)

ramet was recorded was tested across stem treatments andfertilization treatments using Kruskal-Wallis tests Kruskal-Wallis was used in this instance because assumptions ofANOVA could not be met for some groups and data (andassociated residuals) could not be transformed to achievenormality and homogeneity of variances for all groups Initialheight was statistically different among the stem treatmentsgalled ramets (mean plusmn SE 330 plusmn 19 cm) were between41 and 50 taller than clipped (234 plusmn 26 cm) and intactramets (220 plusmn 17 cm) respectively (Kruskal-Wallis 1205942 =23794 119889119891 = 2 and 119875 lt 0001) This difference is likelybecause apical meristems above the canopy are more likelyto be visible to ovipositing females thus two-way analysis ofcovariance (ANCOVA) was used on seed count seed massand the number of days budding blooming and ripening(phenological timing) with initial height as the covariateANCOVA included bootstrapping (1000 bootstrap samples)to improve confidence limits due to small sample size forsome groups For phenological timing although varianceswere homogeneous sample sizes for flowering ramets in theclipped group were small (119899 = 7) thus these results shouldbe viewed with caution Seed germination rates were testedusing chi-square (1205942) tests Significant ANCOVA results wereanalyzed using contrasts with automatic Sidak correctionSignificant ANOVA results among stem treatments wereanalyzed using Tukeyrsquos HSD tests Significant Kruskal-Wallisresults among stem treatments were analyzed using Mann-Whitney 119880 with Bonferroni correction (120572 = 0017) All sta-tistical tests were conducted using PASW Statistics (currentlyknown as SPSS Statistics) version 1800 (IBMArmonkNY)

3 Results

31 First Bud Break Experiment Stem treatment had a highlysignificant effect on the number of days to first bud break(119865224= 45568 119875 lt 0001) Both galled and clipped sur-

viving ramets broke bud within the first 40 days (mean plusmn SE

364 plusmn 63 and 336 plusmn 43 resp) and were statistically similarwhile intact surviving ramets were significantly slower andbroke bud about 80 days later (1138 plusmn 18) (Figure 1(a)) Stemtreatment also had a highly significant effect on the numberof surviving ramets that broke bud by eight weeks (1205942 =46000 119889119891 = 2 and 119875 lt 0001) (Figure 1(b)) Slightly moreclipped ramets than galled ramets broke bud in the first fiveweeks By eight weeks 100 of surviving galled and clippedramets had broken bud while no intact ramets had brokenbud by this time Intact ramets did not begin to break buduntil sixteen weeks

Stem treatment had a highly significant effect on thedistance (cm) from the stem terminal to the first bud break(119865224= 12474 119875 lt 0001) Clipped ramets broke bud

significantly closer to the terminal with an average distanceof 13 plusmn 02 cm from the terminal compared to intactramets which broke bud an average distance of 66 plusmn 20 cm(Figure 2(a)) Galled ramets broke bud an average distance of30 plusmn 07 cm from the terminal and were statistically similarto both the clipped and intact groups Stem treatment alsohad a highly significant effect on the node bearing first budbreak (1205942 = 14534 119889119891 = 4 and 119875 = 0006) as counted fromthe stem terminal (node 0) (Figure 2(b)) Clipped ramets firstbroke bud at an average node of 08plusmn02 Approximately 25of clipped ramets broke bud directly at the stem terminal andwere the only group to do so Galled ramets broke bud at anaverage node of 19 plusmn 03 with most bud breaks occurring atnode 1 and the remaining breaks being split evenly betweennodes 2 and 3 Intact ramets broke bud at an average nodeof 45 plusmn 12 and never broke bud closer to the terminal thannode 3 One ramet broke bud first at node 8

32 Stem Condition and Nutritional Status Experiment Stemtreatment had no effect on the total number of stems at theend of the experiment (week 25) (1205942 = 0986 119889119891 = 2and 119875 = 0611) with galled ramets having an average of41 plusmn 06 (SE) stems compared to 41 plusmn 05 stems for clipped

Journal of Botany 5


A B

B

AP lt 0001

00

20

40

60

80

100Av

erag

e dist

ance

(cm

)

(a)

Galled Clipped Intact (control)

Closest tostem terminal

Farthest fromstem terminal

P = 0006

0

2

4

6

8

10

Freq

uenc

y

42 31 5 80 6 7Node

(b)

Figure 2 In first bud break experiment (a) average distance to first bud break in centimeters as measured from the stem terminal to thenode bearing the first lateral meristem to break bud with SEM error bars (119865

224

= 12474 119875 lt 0001) and (b) frequencies of first bud breaksoccurring at different nodes (0 = stem terminal 1 = first node below terminal etc) (1205942 = 14534 119889119891 = 4 and 119875 = 0006) In (a) datawere square-root transformed to meet ANOVA assumptions but are presented untransformed for clarity Different letters indicate significantdifferences among treatments (Tukeyrsquos post hoc with Bonferroni correction to 120572 = 0017)


1

2

3

4

5

6

Aver

age n

umbe

r of s

tem

s

P = 0611

(a)Fertilized Unfertilized

A

B

0

1

2

3

4

5

6

Aver

age n

umbe

r of s

tem

s

P = 0001

(b)

Figure 3 In stem-nutrition experiment average number of stems at week 25 with SEM error bars across (a) stem treatments (1205942 =0986 119889119891 = 2 and 119875 = 0611) and (b) fertilization treatments (1205942 = 11973 119889119891 = 1 and 119875 = 0001) Different letters indicate significantdifferences among treatments

ramets and 46 plusmn 05 stems for intact ramets (Figure 3(a))Galled ramets had dramatic increases in stem count withinthe first month while clipped ramets appeared to be delayedin sprouting new stems Stem count increased modestly inintact ramets until week 15 after which average stem countin that group was comparable to that in galled and clippedplants Approximately 27 of intactunfertilized (control)ramets broke bud by week 3 and 44 by week 11 when flowerbuds began to appear on the ramets Fertilization treatmenthad a highly significant effect on the number of stems at theend of the experiment (1205942 = 11973 119889119891 = 1 and 119875 = 0001)with fertilized ramets having an averagemaximumof 49plusmn04stems compared to 36 plusmn 05 stems for unfertilized ramets(Figure 3(b))

Stem treatment had a highly significant effect on theaverage number of days before first flowering occurred inflowering ramets (1205942 = 19747 119889119891 = 2 and 119875 lt 0001) withclipped ramets flowering significantly later than either galledand intact ramets (Figure 4(a)) With Bonferroni correction(120572 = 0017) galled and intact ramets were not significantlydifferent Clipped ramets flowered at an average of 1362 plusmn 47days after the beginning of the experiment three weeks laterthan galled ramets (1159 plusmn 32 days) and a full month laterthan intact ramets (1062 plusmn 28 days) Fertilization treatmenthad no effect on the number of days to first flowering (1205942 =1323 119889119891 = 1 and 119875 = 0250) with fertilized rametsflowering an average of about five days earlier (1116 plusmn 28days) than unfertilized ramets (1166plusmn40days) (Figure 4(b))

6 Journal of Botany


A

A

B

90

100

110

120

130

140

150Av

erag

e day

s to

first

flow

erP lt 0001


90

100

110

120

130

140

150

Aver

age d

ays t

o fir

st flo

wer

P = 0250

(b)


A

B

A

10

15

20

25

30

35

Aver

age d

ays r

ipen

ing

P = 0038

(c)Fertilized Unfertilized

A

B

10

15

20

25

30

35

Aver

age d

ays r

ipen

ing

P = 0006

(d)

Figure 4 In stem-nutrition experiment average number of days until appearance of first flower bud in flowering ramets only with SEMerror bars across (a) stem treatments (1205942 = 19747 119889119891 = 2 and 119875 lt 0001) and (b) fertilization treatments (1205942 = 1323 119889119891 = 1 and119875 = 0250) and average number of days seed heads ripened with SEM error bars across (c) stem treatments and (d) fertilization treatments(stem treatment 119865

247

= 3566 119875 = 0038 fertilization treatment 119865147

= 8281 119875 = 0006 stem times fertilization 119865247

= 1401 119875 = 0258covariate 119865

147

= 0013 119875 = 0911) Different letters indicate significant differences among treatments (Mann-Whitney for Kruskal-Wallisand Tukeyrsquos for ANCOVA for stem treatments with Bonferroni correction to 120572 = 0017)

Stem treatment had no effect on the number of days inflower bud stage (119865

246= 0298 119875 = 0744) with flower heads

on galled ramets spending an average of 245 plusmn 20 days asflower buds clipped ramets an average of 220 plusmn 28 daysand intact ramets an average of 235 plusmn 14 days Fertilizationtreatment also had no effect on the length of flower bud stage(119865146= 0004 119875 = 0950) with flower heads on fertilized

ramets spending an average of 236 plusmn 14 days as flower budsand on unfertilized ramets an average of 237 plusmn 17 daysNo significant interaction between stem and fertilizationtreatments was revealed (119865

246= 0057 119875 = 0945) The

covariate initial height also had no significant influence onthe length of flower bud stage (119865

146= 0004 119875 = 0949)

Stem treatment had no effect on the number of days in theblooming stage (119865


on galled ramets blooming for an average of 255plusmn14 days onclipped ramets for an average of 213plusmn27 days and on intactramets for an average of 265plusmn15days Fertilization treatmentalso had no effect on the length of blooming stage (119865

146=

0848 119875 = 0363) with flower heads on fertilized ramets

blooming for an average of 258plusmn13 days and on unfertilizedramets for an average of 246 plusmn 15 days No significantinteraction between stem and fertilization treatments wasrevealed (119865

246= 0267 119875 = 0767) Again the covariate

initial height also had no significant influence on bloomingtime (119865

146= 0261 119875 = 0612)

However stem treatment had a significant effect onthe number of days seed heads spent ripening (119865

247=

3566 119875 = 0038) with those on clipped ramets ripeningsignificantly earlier than those on galled and intact rametswhich were statistically similar to each other (Figure 4(c))Planned contrasts indicated that clipping had a significantlynegative effect on ripening time compared to the galled group(119875 = 0006 95 CI [1800 10291]) and the intact group(119875 = 0011 95 CI [minus12616 minus1719]) Again the galledgroup was intermediate between the control and clippedgroups but it was not significantly different from the intactgroup (119875 = 0419 95 CI [minus6035 2563]) Seed heads onclipped ramets ripened for an average of 244 plusmn 28 days orabout 4-5 fewer days than galled (283 plusmn 16 days) and intact

Journal of Botany 7


10

20

30

40

50

60

70Fl

ower

ing

ram

ets (

)

n = 19

n = 11

n = 40

P lt 0001


0

10

20

30

40

50

60

70

Flow

erin

g ra

met

s (

)

n = 102

n = 108

P = 0403

(b)


10

20

30

40

Tota

l see

d he

ads p

rodu

ced

n = 24

n = 7

n = 16

P = 0010


0

10

20

30

40

Tota

l see

d he

ads p

rodu

ced n = 30

n = 17

P = 0080

(d)

Figure 5 In stem-nutrition experiment total number of ramets producing flower buds across (a) stem treatments (1205942 = 19229 119889119891 = 2 and119875 lt 0001) and (b) fertilization treatments (1205942 = 0700 119889119891 = 1 and 119875 = 0403) and total number of seed heads produced across (c) stemtreatments (1205942 = 9234 119889119891 = 2 and 119875 = 0010) and (d) fertilization treatments (1205942 = 3064 119889119891 = 1 and 119875 = 0080)

ramets (294 plusmn 11 days) Fertilization treatment also had ahighly significant effect on the length of the ripening stage(119865147= 8281 119875 = 0006) with seed heads on fertilized

ramets ripening for an average of 296 plusmn 10 days or nearlyfour days longer than unfertilized ramets (258 plusmn 17 days)(Figure 4(d)) No significant interaction between stem andfertilization treatments was revealed (119865

247= 1401 119875 =

0258) The covariate initial height also had no significantinfluence on ripening time (119865

147= 0013 119875 = 0911)

Stem treatment had a highly significant effect on thenumber of ramets producing flower buds (1205942 = 19229 119889119891 =2 and 119875 lt 0001) with intact ramets producing twiceas many total flower buds (40) as galled ramets (19) andnearly four times as many flower buds as clipped ramets(11) (Figure 5(a)) Fertilization treatment had no effect on thenumber of ramets producing flower buds (1205942 = 0700 119889119891 =1 and 119875 = 0403) with fertilized ramets producing 39flower buds and unfertilized ramets producing 31 flower buds(Figure 5(b)) Stem treatment also had a highly significanteffect on the total number of seed heads produced (1205942 =9234 119889119891 = 2 and 119875 = 0010) with intact ramets producinga total of 24 seed heads compared to 16 for galled ramets

and 7 for clipped ramets (Figure 5(c)) Although suggestivefertilization treatment had no effect on the number of seedheads produced (1205942 = 3064 119889119891 = 1 and 119875 = 0080) withfertilized ramets producing 30 seed heads and unfertilizedramets producing 17 seed heads (Figure 5(d))

Both stem treatment and fertilization treatment hadhighly significant effects on normal versus abnormal seeddevelopment (stem 1205942 = 13499 119889119891 = 2 and 119875 lt 001fertilization 1205942 = 60314 119889119891 = 1 and 119875 lt 0001) Stemtreatment also had a significant effect on the average numberof apparently normally developed seeds per seed head (119865

247=

4370 119875 = 0019) (Figure 6(a)) Planned contrasts indicatedthat clipping had a significantly negative effect on seed countcompared to the galled group (119875 = 0020 95 CI [603966450]) and the intact group (119875 = 0005 95 CI [minus95368minus17834]) The galled group was not significantly differentfrom the intact group (119875 = 0005 95 CI [minus95368 minus17834])but was lower as expected Average seed count per seed headwas significantly lower for clipped ramets at 581 plusmn 140 perseed head compared to 839 plusmn 114 seeds per head for galledramets and 1007 plusmn 86 seeds per head for intact rametsFertilization treatment also had a significant effect on seed

8 Journal of Botany


A

B

A

40

60

80

100

120Av

erag

e num

ber o

f see

dsP = 0019


A

B

40

60

80

100

120

Aver

age n

umbe

r of s

eeds

P = 0020

(b)

Figure 6 Average seed count per seed head with SEM error bars across (a) stem treatments and (b) fertilization treatments in the stem-nutrition experiment (stem treatment 119865

247


= 5881 119875 = 0020 stem times fertilization119865247

= 1223 119875 = 0305 covariate 119865147

= 2941 119875 = 0094) Different letters indicate significant differences among treatments (Tukeyrsquoswith Bonferroni correction to 120572 = 0017 for stem treatments)

count (119865147= 5881 119875 = 0020) with average seed count

per seed head being significantly higher in fertilized ramets(952 plusmn 85) compared to unfertilized ramets (771 plusmn 96)(Figure 6(b)) No significant interaction between stem andfertilization treatments was revealed (119865

247= 1223 119875 =

0305) The covariate initial height also had no significantinfluence on seed count (119865

147= 2941 119875 = 0094)

Stem treatment had no effect on seed mass of normallydeveloped seeds (119865

247= 0856 119875 = 0433) with average

mass per seed being 09 plusmn 01mg for galled ramets comparedto 08 plusmn 01mg for clipped ramets and 08 plusmn 00mg forintact ramets Although fertilization produced slightly largerseeds the effect on seed mass was not significant (119865

147=

0362 119875 = 0551) with average mass per seed being 09 plusmn00mg for fertilized ramets compared to 08 plusmn 01mg forunfertilized ramets No significant interaction between stemand fertilization treatments was found (119865

247= 0060 119875 =

0942) The covariate initial height also had no significantinfluence on seed mass (119865

147= 1595 119875 = 0214) Seed

germinations were low across all treatments with only 92of all sowed seeds germinating Stem treatment had no effecton germination (1205942 = 1582 119889119891 = 2 and 119875 = 0453) with9 germination success in the galled group compared to 7in the clipped group and 10 in the intact group Curiouslyfertilization treatment had a highly significant effect on seedgermination success (1205942 = 8418 119889119891 = 1 and 119875 =0004) with 7 germination success in the fertilized groupcompared to 13 in the unfertilized group

4 Discussion

The first bud break experiment investigated the strength ofapical dominance and the effects on different types of stemdamage on it The distance at which intact ramets brokebud and the extended amount of time it took for themto break bud suggest that apical dominance is strong inBorrichia frutescens However stem count at the end of the

stem-nutrition experiment (25 weeks) was similar across alltreatment groups and at least some ramets in all treatmentsbroke bud shortly after the experiment began This apparentcontradiction is likely due to differences in the strength ofapical dominance at different times of the season the stem-nutrition experimentwas started in January before floweringwhile the first bud break experiment was started in Mayafter flowering began Changes in photoperiod in spring[52ndash54] and flowering [4 55] are both known to triggera weakening in apical dominance in some plant speciespossibly to maximize the number of meristems available forflower head production Additionally foliage in January wassparse and became denser by May at which point single-stemmed (ie young) B frutescens used in the bud breakexperiment were notably shorter and more shaded than theirneighbors Light competition has been known to strengthenapical dominance and reduce branching [4 53 56] Thefinding that apical dominance in intact ramets weakensbefore flowering is important because overcompensation canoccur only when apical dominance is strong and the planthas a bank of dormant buds in reserve for recovery afterdamage [3ndash5 10 11 34] In order for reproductive benefitsto be realized strong apical dominance must be maintainedbefore and during flowering so that its disruption leads tosignificantly more flower heads and seeds compared to intactramets Clearly that was not the case in this study

Borrichia frutescens is a long-lived perennial and evenunder nonstressful conditions (eg readily available watersoil nutrients etc) damage may extend phenological stages(eg growth flowering etc) For instance if the floweringstage is delayed it may affect the fitness of the plant byaltering pollination opportunities [57] In the stem-nutritionexperiment clipping was detrimental to reproduction interms of significant delays in flowering and shorter seed headripening times Delays in flowering suggest that florets onclipped ramets may have missed the window of opportunityfor cross-pollinating with other florets in the population

Journal of Botany 9

while shortened ripening time may have resulted in poorseed development Such phenological abnormalities can beexpected to affect seed production and indeed clippedramets produced significantly fewer seed heads and normallydeveloped seeds per seed head

Clipping may have been detrimental because removingthe apical meristem also involved removing the terminal pairof leaves associatedwith it Since single-stemmed rametsweresparsely foliated in January removing even a single pair ofleavesmayhave drastically reduced the plantsrsquo photosyntheticarea and caused a carbon limitation Such a limitation maydelay regrowth which was evidenced by the one-monthlag in stem count in clipped ramets Since regrowth canredirect nutrients away from reproduction when it precedesflowering in the population [3 16 58] the subsequent one-month delay in flowering in clipped ramets is not surprisingAdditionally naturally occurring apical meristem damagesimilar to clipping such as chewing by grasshoppers (egOrchelimum fidicinium) is seen rarely in the field (AnthonyM Rossi personal observation) suggesting that this typeof damage probably does not exert strong selective pressureand that B frutescens is poorly adapted to it A high riskof chewing would need to exist for a beneficial or neutralresponse to it to be adaptive [16 19 52]

Both clipping and galling had detrimental effects on Bfrutescens but galling had less impact Borrichia frutescenshas had a long-term association with galling by Asphondyliaborrichiae [43] which may have exerted strong selectivepressure over time to which B frutescens is better adaptedand not overly burdened Indeed galled ramets were slightlybut not significantly different from intact ramets for severalof the performance variables assessed in the current studyHowever galled ramets produced 50 fewer flower buds thanintact ramets suggesting that galling may present a formof resource regulation which has been identified in othergalling systems [31 32] Meristems damaged by cecidogenesisor other types of herbivory are essentially removed fromthe pool of meristems available for the plantrsquos growth andreproduction [5 7 8 10 11] Additionally although leaves atthe galled terminal as well as the gall itself can remain greenfor some time galls can significantly redirect nutrients fromplant functions to feed the gall-inducing organism [5 22 2326 59] making any photosynthesis by those tissues likelybeneficial only to the gall-inducer and not the plant itselfThus the reallocation of meristems and nutrients from plantgrowth and reproduction to A borrichiae gall developmentmay ensure a steady supply of available (nonflowering)meris-tems for future generations of gall midges by maintainingapical meristems of B frutescens in a nonflowering state

Borrichia frutescens occurs primarily in saline habitatsand as Fernandes and Ribeiro [57] point out stress andnutrient availability are likely to affect a plantrsquos ability torecover from damage The fate of regrown shoots (egsurvival growth rate and galling rate) was not assessedin the current study but they may have performed poorlycompared to undamaged primary shoots However being atidal environment water is not likely to be limiting Addi-tionally only three variables increased significantly undernitrogen supplementation final stem count number of days

for seed head ripening and the number of normal seedsper seed head These results suggest that nitrogen also isprobably not a limiting nutrient at this site and the smallamount used in this experiment may have been insignificantcompared to the twice-daily tidal influx of nutrients Aprevious fertilization study reported vigorous regrowth andother beneficial responses of Borrichia frutescens but thatstudy utilized relatively high concentrations of highly solubleinorganic ammonium nitrate [40] Thus stem number andseed count may be phenotypically plastic characteristics thatrespond more readily to changes in nutrient level and otherenvironmental conditions compared to the other responsevariables tested in this experiment Indeed previous studiessuggest that nutrient supplementation via roots may overrideapical dominance when it is weak and result in the growthof new stems [4 11 54 55] Nutrient supplementation canalso increase the production of normally developed seeds byallowing plants to allocate more nutrients to reproduction[58] An increase in the number of days for seed head ripen-ing may also enhance seed development and decrease thechances of seed abortion by allowing fertilized ovamore timeto acquire adequate nutrient and energy stores Finally whilethe count of normally developed seeds varied significantlyacross both stem treatments and fertilizer treatments in thisexperiment seed mass an important measure of seed qualityand energy reserves [3 60 61] did not This result supportsthe observation that seed count inmany plant species tends tovary in response to environmental changes while seed massremains relatively constant [60 61]

5 Conclusion

Clearly the manner of apical meristem damage had an effecton the plantrsquos compensatory response Borrichia frutescensappears to be poorly adapted to damage that abruptlyremoves the apical meristem (eg chewing damage) espe-cially when it occurs early in the season However evenclipped plants which exhibited more adverse effects thangalled ones largely recovered vegetative growth by the end ofthe study Results from this study suggest that B frutescens isbetter adapted to galling byA borrichiae in terms of regrowthand reproduction compared to chewing damage Moreoverwe suggest possible resource regulation of apical meristemsby the gall-inducer

Conflict of Interests

The authors declare that there are no conflict of interestsregarding the publication of this paper

Acknowledgments

The authors thank Dr DMoon (University of North Florida)and Dr J Smith (University of Florida) for reviewing thispaper M Masdea N Millan and R Fuller for assisting withfield research and J Evans (Sanibel-Captiva ConservationFoundationNative PlantNursery) for information aboutBor-richia frutescens seed germination In addition we would like

10 Journal of Botany

to thank the anonymous reviewers for their comments whichimproved the paperThisworkwas conducted underNationalPark Service permit No TIMU-2013-SCI-0001 study NoTIMU-00014 It was funded in part by a Timucuan PreserveResearch Grant awarded by the Timucuan Ecological andHistoric Preserve (US NPS) and Timucuan Trail ParksFoundation and a University of North Florida Travel Awardfrom the UNF Biology Department

References

[1] D A Jameson ldquoResponses of individual plants to harvestingrdquoThe Botanical Review vol 29 no 4 pp 532ndash594 1963

[2] D R Strong J H Lawton and R Southwood Insects onPlants Community Patterns and Mechanisms Harvard Univer-sity Press Cambridge Mass USA 1984

[3] KN Paige andTGWhitham ldquoOvercompensation in responseto mammalian herbivory the advantage of being eatenrdquo Amer-ican Naturalist vol 129 no 3 pp 407ndash416 1987

[4] L W Aarssen ldquoHypotheses for the evolution of apical domi-nance in plants implications for the interpretation of overcom-pensationrdquo Oikos vol 74 no 1 pp 149ndash156 1995

[5] R J Marquis ldquoPlant architecture sectoriality and plant toler-ance to herbivoresrdquo Vegetatio vol 127 no 1 pp 85ndash97 1996

[6] A-P Huhta T Lennartsson J Tuomi P Rautio and K LaineldquoTolerance of Gentianella campestris in relation to damageintensity an interplay between apical dominance and her-bivoryrdquoEvolutionary Ecology vol 14 no 4ndash6 pp 373ndash392 2000

[7] K Lehtila ldquoModelling compensatory regrowth with bud dor-mancy and gradual activation of budsrdquo Evolutionary Ecologyvol 14 no 4ndash6 pp 315ndash330 2000

[8] K A Stowe R J Marquis C G Hochwender and E L SimmsldquoThe evolutionary ecology of tolerance to consumer damagerdquoAnnual Review of Ecology and Systematics vol 31 pp 565ndash5952000

[9] J Fornoni J Nunez-Farfan and P L Valverde ldquoEvolutionaryecology of tolerance to herbivory advances and perspectivesrdquoComments on Theoretical Biology vol 8 no 6 pp 643ndash6632003

[10] M J Wise and W G Abrahamson ldquoBeyond the compensatorycontinuum environmental resource levels and plant toleranceof herbivoryrdquo Oikos vol 109 no 3 pp 417ndash428 2005

[11] M J Wise and W G Abrahamson ldquoApplying the limitingresource model to plant tolerance of apical meristem damagerdquoAmerican Naturalist vol 172 no 5 pp 635ndash647 2008

[12] S Strauss and A Zangerl ldquoPlant-insect interactions in terres-trial ecosystemsrdquo in Plant-Animal Interactions An EvolutionaryApproach C Herrera and O Pellmyr Eds pp 77ndash106 Wiley-Blackwell Hoboken NJ USA 2009

[13] P R Ehrlich and P H Raven ldquoButterflies and plants a study incoevolutionrdquo Evolution vol 18 no 4 pp 586ndash608 1964

[14] A Kessler and I T Baldwin ldquoPlant responses to insect her-bivory the emerging molecular analysisrdquo Annual Review ofPlant Biology vol 53 pp 299ndash328 2002

[15] J P Rosenthal and P M Kotanen ldquoTerrestrial plant toleranceto herbivoryrdquo Trends in Ecology and Evolution vol 9 no 4 pp145ndash148 1994

[16] T Lennartsson P Nilsson and J Tuomi ldquoInduction of over-compensation in the field gentian Gentianella campestrisrdquoEcology vol 79 no 3 pp 1061ndash1072 1998

[17] B L Benner ldquoEffects of apex removal and nutrient supple-mentation on branching and seed production inThlaspi arvense(Brassicaceae)rdquo American Journal of Botany vol 75 no 5 pp645ndash561 1988

[18] DW Inouye ldquoThe consequences of herbivory amixed blessingfor Jurinea mollis (Asteraceae)rdquo Oikos vol 39 no 2 pp 269ndash272 1982

[19] T G Whitham J Maschinski K C Larson and K N PaigeldquoPlant responses to herbivory the continuum from negative topositive and underlying physiological mechanismsrdquo in Plant-Animal Interactions Evolutionary Ecology in Tropical and Tem-perate Regions P W Price T M Lewinsohn G W Fernandesand W W Benson Eds pp 227ndash256 John Wiley amp Sons NewYork NY USA 1991

[20] R Karban and S Y Strauss ldquoEffects of herbivores on growth andreproduction of their perennial host Erigeron glaucusrdquo Ecologyvol 74 no 1 pp 39ndash46 1993

[21] POlejniczak ldquoOvercompensation in response to simulated her-bivory in the perennial herb Sedum maximumrdquo Plant Ecologyvol 212 no 11 pp 1927ndash1935 2011

[22] A E Weis R Walton and C L Crego ldquoReactive plant tissuesites and the population biology of gall makersrdquo Annual Reviewof Entomology vol 33 pp 467ndash486 1988

[23] F Dreger-Jauffret and J D Shorthouse ldquoDiversity of gall-inducing insects and their gallsrdquo in Biology of Insect-InducedGalls J D Shorthouse andO Rohfritsch Eds pp 8ndash33 OxfordUniversity Press New York NY USA 1992

[24] M S Mani ldquoIntroduction to cecidologyrdquo in Biology of Insect-Induced Galls J D Shorthouse and O Rohfritsch Eds pp 3ndash7Oxford University Press New York NY USA 1992

[25] O Rohfritsch ldquoPatterns in gall developmentrdquo in Biology ofInsect-Induced Galls J D Shorthouse and O Rohfritsch Edspp 60ndash86 Oxford University Press New York NY USA 1992

[26] A Raman C W Schaefer and T M Withers ldquoGalls and gall-inducing arthropods an overview of their biology ecology andevolutionrdquo in Biology Ecology and Evolution of Gall-InducingArthropods A Raman C W Schaefer and T M Withers Edspp 1ndash34 Science Publishers Enfield NH USA 2005

[27] J Yukawa and O Rohfritsch ldquoBiology and ecology of gall-inducing Cecidomyiidae (Diptera)rdquo in Biology Ecology andEvolution of Gall-Inducing Arthropods A Raman C W Schae-fer and T M Withers Eds pp 273ndash304 Science PublishersEnfield NH USA 2005

[28] R J Gagne The Plant-Feeding Gall Midges of North AmericaCornell University Press Ithaca NY USA 1989

[29] A M Rossi ldquoSpeciation processes among insectsrdquo in Encyclo-pedia of Entomology J L Capinera Ed pp 2060ndash2062 KluwerAcademic Publishers London UK 2004

[30] M A A Carneiro C S A Branco C E D Braga et al ldquoAre gallmidge species (Diptera Cecidomyiidae) host-plant specialistsrdquoRevista Brasileira de Entomologia vol 53 no 3 pp 365ndash3782009

[31] T P Craig P W Price and J K Itami ldquoResource regulation bya stem-galling sawfly on the arroyo willowrdquo Ecology vol 67 no2 pp 419ndash425 1986

[32] H Roininen P W Price and J Tahvanainen ldquoField test ofresource regulation by the bud-galling sawflyEuuramucronataon Salix cinereardquo Holarctic Ecology vol 11 no 2 pp 136ndash1391988

[33] A M Rossi and D R Strong ldquoA new species of Aspho-ndylia (Diptera Cecidomyiidae) on Borrichia (Asteraceae)

Journal of Botany 11

from Floridardquo Proceedings of the Entomological Society of Wash-ington vol 92 no 4 pp 732ndash735 1990

[34] M M Espırito-Santo F D S Neves F R Andrade-Neto andG W Fernandes ldquoPlant architecture and meristem dynamicsas the mechanisms determining the diversity of gall-inducinginsectsrdquo Oecologia vol 153 no 2 pp 353ndash364 2007

[35] J M CarltonAGuide to Common Florida Salt Marsh andMan-grove Vegetation Florida Department of Natural ResourcesFlorida Marsh Research Publications St Petersburg Fla USA1975

[36] A Cronquist Vascular Flora of the Southeastern United StatesVol 1 Asteraceae University of North Carolina Press ChapelHill NC USA 1980

[37] A E Antlfinger ldquoThe genetic basis of microdifferentiation innatural and experimental populations of Borrichia frutescens inrelation to salinityrdquo Evolution vol 35 no 6 pp 1056ndash1068 1981

[38] W H Duncan andM B Duncan Seaside Plants of the Gulf andAtlantic States Smithsonian Institution Press Washington DCUSA 1987

[39] P Biber J D Caldwell S R Caldwell and M Marenberg Sea-Oxeye Daisy Borrichia Frutescens Propagation Guide Centerfor Plant Restoration and Coastal Plant Research University ofSouthern Mississippi Ocean Springs Miss USA 2013

[40] AMRossi PD StilingD R Strong andDM Johnson ldquoDoesgall diameter affect the parasitism rate ofAsphondylia borrichiae(Diptera Cecidomyiidae)rdquoEcological Entomology vol 17 no 2pp 149ndash154 1992

[41] A M Rossi and P D Stiling ldquoIntraspecific variation in growthrate size and parasitism of galls induced by Asphondyliaborrichiae (Diptera Cecidomyiidae) on three host speciesrdquoAnnals of the Entomological Society of America vol 88 no 1pp 39ndash44 1995

[42] AMRossi P StilingMVCattell andT I Bowdish ldquoEvidencefor host-associated races in a gall-forming midge trade-offs inpotential fecundityrdquo Ecological Entomology vol 24 no 1 pp95ndash102 1999

[43] K Stokes P Stiling M Gilg and A M Rossi ldquoThe gall midgeAsphondylia borrichiae Rossi amp Strong (Diptera Cecidomyi-idae) an indigenous example of host-associated sympatricgenetic divergencerdquo Environmental Entomology vol 41 no 5pp 1246ndash1254 2012

[44] J C Roskam ldquoEvolution of the gall-inducing guildrdquo in Biologyof Insect-InducedGalls J D Shorthouse andO Rohfritsch Edspp 34ndash49 Oxford University Press New York NY USA 1992

[45] P Stiling A M Rossi D R Strong and D M JohnsonldquoLife history and parasites of Asphondylia borrichiae (DipteraCecidomyiidae) a gall maker on Borrichia frutescensrdquo FloridaEntomologist vol 75 no 1 pp 130ndash137 1992

[46] J Yukawa ldquoSynchronization of gallers with host plant phenol-ogyrdquo Population Ecology vol 42 no 2 pp 105ndash113 2000

[47] A M Rossi M Murray K Hughes M Kotowski D C Moonand P Stiling ldquoNon-random distribution among a guild ofparasitoids implications for community structure and hostsurvivalrdquo Ecological Entomology vol 31 no 6 pp 557ndash5632006

[48] D Te Strake A H Keagy and P D Stiling ldquoFungi associatedwith Borrichia frutescens (Asteraceae) insect galls and endo-phytesrdquo SIDA Contributions to Botany vol 22 no 1 pp 755ndash763 2006

[49] P Stiling and A M Rossi ldquoCoastal insect herbivore communi-ties are affectedmore by local environmental conditions than by

plant genotyperdquo Ecological Entomology vol 20 no 2 pp 184ndash190 1995

[50] P Stiling A M Rossi M Cattell and T I Bowdish ldquoWeakcompetition between coastal insect herbivoresrdquo Florida Ento-mologist vol 82 no 4 pp 599ndash608 1999

[51] D CMoon and P Stiling ldquoThe influence of species identity andherbivore feedingmode on top-down andbottom-up effects in asalt marsh systemrdquoOecologia vol 133 no 2 pp 243ndash253 2002

[52] E Van Der Meijden ldquoHerbivory as a trigger for growthrdquoFunctional Ecology vol 4 no 4 pp 597ndash598 1990

[53] K A Franklin ldquoShade avoidancerdquoNew Phytologist vol 179 no4 pp 930ndash944 2008

[54] M A Domagalska and O Leyser ldquoSignal integration in thecontrol of shoot branchingrdquo Nature Reviews Molecular CellBiology vol 12 no 4 pp 211ndash221 2011

[55] M G Cline ldquoApical dominancerdquoThe Botanical Review vol 57no 4 pp 318ndash358 1991

[56] H Smith and G CWhitelam ldquoThe shade avoidance syndromemultiple responses mediated by multiple phytochromesrdquo PlantCell and Environment vol 20 no 6 pp 840ndash844 1997

[57] GW Fernandes and S P Ribeiro ldquoPlant response to herbivorytwo examples from the neotropicsrdquo Ecotropicos vol 3 no 2 pp77ndash86 1990

[58] A G Stephenson ldquoFlower and fruit abortion proximate causesand ultimate functionsrdquo Annual Review of Ecology and System-atics vol 12 pp 253ndash279 1981

[59] O Rohfritsch ldquoPlants gall midges and fungi a three-component systemrdquo Entomologia Experimentalis et Applicatavol 128 no 1 pp 208ndash216 2008

[60] J L Harper Population Biology of Plants Academic PressLondon UK 1977

[61] B A Schaal ldquoReproductive capacity and seed size in LupinustexensisrdquoAmerican Journal of Botany vol 67 no 5 pp 703ndash7091980

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Anatomy Research International

PeptidesInternational Journal of


Hindawi Publishing Corporation httpwwwhindawicom

International Journal of

Volume 2014

Zoology


Molecular Biology International

GenomicsInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


BioinformaticsAdvances in

Marine BiologyJournal of



Signal TransductionJournal of


BioMed Research International

Evolutionary BiologyInternational Journal of



Biochemistry Research International

ArchaeaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Genetics Research International


Advances in

Virolog y

Hindawi Publishing Corporationhttpwwwhindawicom

Nucleic AcidsJournal of

Volume 2014

Stem CellsInternational



Enzyme Research



Microbiology

2 Journal of Botany

insect or fungus and its host plant and results in a tumor-likeovergrowth of plant tissue [22ndash28] Gall-inducers tend to bespecialists and highly specific to their particular host speciesgenus or family and to the organ they attack suggesting tightcoevolutionary relationships in these systems [22 23 28 29]Gagne [28] reports that gall midges (Cecidomyiidae) are usu-ally monophagous (one host plant species) or oligophagous(a few closely related species) In a review of the literaturespanning 196 neotropical species of gall midges Carneiroet al [30] found that 924 were monophagous and 56were oligophagous Additionally 908 of the cecidomyiidspecies reviewed were found to induce galls on only oneplant organ (leaves flowers or stems) further supportingthe claim that they are host specialists Galling of the apicalmeristem can disrupt apical dominance and initiate axillaryshoots [27 31 32] Thus since host plants likely coadaptedwith their associated gall inducers it is reasonable that plantsattacked by apical gall inducersmay demonstrate tolerance orcompensation in response to the damage

Galls of the midge Asphondylia borrichiae on the apicalmeristem of sea oxeye daisy (Borrichia frutescens) are associ-ated with stem bifurcation below the gall [33] Other types ofnaturally occurring apicalmeristemdamage such as chewingby grasshoppers (egOrchelimumfidicinium) are seen rarelyin the field (Anthony M Rossi personal observation)

The overall goal of this research was to examine thecompensatory response of B frutescens to different types ofapical meristem damage in young single-stemmed rametsDamage to the meristem was either sudden (ie clippingto simulate chewing) or gradual via galling which slowlydestroyed the apical meristem Because the plantrsquos ability tocompensate depends largely on having a bank of dormantbuds in reserve [3ndash5 10 11 34] the strength of apicaldominance in B frutescens was investigated in relation toits response to meristem damage A second experimentinvestigated how B frutescens responds to clipping galling byA borrichiae and nutritional differences in terms of growthand reproduction (ie flower head and seed production)

2 Materials and Methods

21 Study System Borrichia frutescens commonly known assea oxeye daisy or bushy seaside tansy is an herbaceoushalophytic perennial shrub found in salt marshes along theUS Atlantic andGulf ofMexico coasts [35] It propagates pri-marily through extensive rhizomes [36ndash38] but also producessmall monoecious flower heads consisting of 15ndash30 petal-likeray florets and 20ndash75 disc florets per flower head [35ndash39]Each floret produces an achene or dry seed-bearing fruit andeach achene contains a single seed Peak flowering is betweenMay and July [38] and flowering rates or the number offlower heads per ramet range from 3 to over 20 (althoughthese rates can be much higher) depending on factors suchas season or access to tidal inundations of nutrients [4041] Under greenhouse conditions seed viability of 90 wasreported by Biber et al [39]

Borrichia frutescens is the primary host plant of the gallmidgeAsphondylia borrichiae [33 41ndash43] AdultA borrichiae

are small (lt3mm long) fragile weak-flying gall midges thatlive for only 2-3 days during which their primary activity isbreeding [2 44ndash46] Female A borrichiae collect the conidiaof a fungal symbiont and deposit the conidia with her eggsinside the apical meristematic tissue of the host plant duringoviposition which induces a gall to form [42 45 47 48]Larvae feed on the fungal symbiont which draws nutrientsfrom plant tissues and they pupate within the gall [47 48]With occasional exceptions female midges appear to avoidovipositing in flower heads [40 42] and the presence of agall typically prevents the apical meristems from flowering[33 42 45] Galls persist on the host plant during springand summer for about seven to ten weeks and senesce aftermidge eclosion typically resulting in the death of the galledapical meristem [33 45] A previous study at the site in2005 found moderate correlation between stem count andgall count (AnthonyM Rossi unpublished data) Aside fromgalling byA borrichiae the sap feeding leafhopper Pissonotusquadripustulatus and the aphid Dactynotus sp are the onlyother herbivores regularly associated with B frutescens inFlorida [49ndash51]

22 Field Site This study was conducted at Timucuan Eco-logical and Historic Preserve in Jacksonville Florida USA(N30∘2210158404510158401015840 W81∘2810158404910158401015840) This site features an intertidalback-marsh community bordered by hammock and consist-ing primarily of Borrichia frutescens Previous studies at thissite [43 47] have found galling onB frutescens to be very high(approximately 30ndash50 of apical meristems) and a strongpositive correlation between stem number and gall count(Anthony M Rossi unpublished data)

23 First Bud Break Experiment To investigate the strengthof apical dominance in B frutescens and to test its response tovarious types of apical meristem damage 25 single-stemmedB frutescens ramets (ie individual plants) were randomlyassigned to a stem treatment in May 2013 (1) galled (2)clipped or (3) intact Ramets in the galled group began theexperiment with a single stem but also had a single live gall(ie green no emergence holes) Clipping was performedby removing the apical meristem and the terminal pair ofleaves with scissors (removing approximately 1 cmof the stemtip) Intact ramets were protected from galling by a mesh bagplaced over the apical meristem and secured with a twist tieTwo-way ANOVA on light readings (Basic Quantum Metermodel BQM-SUN Apogee Instruments Inc Logan UtahUSA) taken inside and outside the mesh bags in sunny andshady conditions revealed no effect of the mesh bags or theirinteraction with light conditions on light penetration (insideversus outside mesh 119865

139= 0004 119875 = 0949 sunny versus

shady 119865139= 3277478 119875 lt 0001 mesh times light 119865

139=

0022 119875 = 0882) Ramets were monitored for bud breakbiweekly and after eight weeks the node number bearingthe bud to break first was recorded (0 = apical meristemor clipped stem tip 1 = first node below apical meristemetc) and its distance measured from the apical meristem orclipped stem tip (nearest 01 cm) Differences in the numberof surviving ramets that broke bud at eight weeks were

Journal of Botany 3








4 Journal of Botany


AA

B

0

20

40

60

80

100

120

Aver

age n

umbe

r of d

ays

P lt 0001

(a)


20

40

60

80

100

Bud

brea

k (

)

P lt 0001n = 1010 n = 1515

n = 021

(b)




3 Results







Journal of Botany 5


A B

B

AP lt 0001

00

20

40

60

80

100Av

erag

e dist

ance

(cm

)

(a)




P = 0006

0

2

4

6

8

10

Freq

uenc

y

42 31 5 80 6 7Node

(b)


224



1

2

3

4

5

6

Aver

age n

umbe

r of s

tem

s

P = 0611


A

B

0

1

2

3

4

5

6

Aver

age n

umbe

r of s

tem

s

P = 0001

(b)




6 Journal of Botany


A

A

B

90

100

110

120

130

140

150Av

erag

e day

s to

first

flow

erP lt 0001


90

100

110

120

130

140

150

Aver

age d

ays t

o fir

st flo

wer

P = 0250

(b)


A

B

A

10

15

20

25

30

35

Aver

age d

ays r

ipen

ing

P = 0038


A

B

10

15

20

25

30

35

Aver

age d

ays r

ipen

ing

P = 0006

(d)


247



= 1401 119875 = 0258covariate 119865

147






246= 0057 119875 = 0945) The


146= 0004 119875 = 0949)




146=





146= 0261 119875 = 0612)


247=


Journal of Botany 7


10

20

30

40

50

60

70Fl

ower

ing

ram

ets (

)

n = 19

n = 11

n = 40

P lt 0001


0

10

20

30

40

50

60

70

Flow

erin

g ra

met

s (

)

n = 102

n = 108

P = 0403

(b)


10

20

30

40

Tota

l see

d he

ads p

rodu

ced

n = 24

n = 7

n = 16

P = 0010


0

10

20

30

40

Tota

l see

d he

ads p

rodu

ced n = 30

n = 17

P = 0080

(d)




247= 1401 119875 =


147= 0013 119875 = 0911)




247=


8 Journal of Botany


A

B

A

40

60

80

100

120Av

erag

e num

ber o

f see

dsP = 0019


A

B

40

60

80

100

120

Aver

age n

umbe

r of s

eeds

P = 0020

(b)


247



= 1223 119875 = 0305 covariate 119865147




247= 1223 119875 =


147= 2941 119875 = 0094)


247= 0856 119875 = 0433) with average


147=


247= 0060 119875 =


147= 1595 119875 = 0214) Seed


4 Discussion




Journal of Botany 9






5 Conclusion




Acknowledgments




References








































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology

Journal of Botany 3








4 Journal of Botany


AA

B

0

20

40

60

80

100

120

Aver

age n

umbe

r of d

ays

P lt 0001

(a)


20

40

60

80

100

Bud

brea

k (

)

P lt 0001n = 1010 n = 1515

n = 021

(b)




3 Results







Journal of Botany 5


A B

B

AP lt 0001

00

20

40

60

80

100Av

erag

e dist

ance

(cm

)

(a)




P = 0006

0

2

4

6

8

10

Freq

uenc

y

42 31 5 80 6 7Node

(b)


224



1

2

3

4

5

6

Aver

age n

umbe

r of s

tem

s

P = 0611


A

B

0

1

2

3

4

5

6

Aver

age n

umbe

r of s

tem

s

P = 0001

(b)




6 Journal of Botany


A

A

B

90

100

110

120

130

140

150Av

erag

e day

s to

first

flow

erP lt 0001


90

100

110

120

130

140

150

Aver

age d

ays t

o fir

st flo

wer

P = 0250

(b)


A

B

A

10

15

20

25

30

35

Aver

age d

ays r

ipen

ing

P = 0038


A

B

10

15

20

25

30

35

Aver

age d

ays r

ipen

ing

P = 0006

(d)


247



= 1401 119875 = 0258covariate 119865

147






246= 0057 119875 = 0945) The


146= 0004 119875 = 0949)




146=





146= 0261 119875 = 0612)


247=


Journal of Botany 7


10

20

30

40

50

60

70Fl

ower

ing

ram

ets (

)

n = 19

n = 11

n = 40

P lt 0001


0

10

20

30

40

50

60

70

Flow

erin

g ra

met

s (

)

n = 102

n = 108

P = 0403

(b)


10

20

30

40

Tota

l see

d he

ads p

rodu

ced

n = 24

n = 7

n = 16

P = 0010


0

10

20

30

40

Tota

l see

d he

ads p

rodu

ced n = 30

n = 17

P = 0080

(d)




247= 1401 119875 =


147= 0013 119875 = 0911)




247=


8 Journal of Botany


A

B

A

40

60

80

100

120Av

erag

e num

ber o

f see

dsP = 0019


A

B

40

60

80

100

120

Aver

age n

umbe

r of s

eeds

P = 0020

(b)


247



= 1223 119875 = 0305 covariate 119865147




247= 1223 119875 =


147= 2941 119875 = 0094)


247= 0856 119875 = 0433) with average


147=


247= 0060 119875 =


147= 1595 119875 = 0214) Seed


4 Discussion




Journal of Botany 9






5 Conclusion




Acknowledgments




References








































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology

4 Journal of Botany


AA

B

0

20

40

60

80

100

120

Aver

age n

umbe

r of d

ays

P lt 0001

(a)


20

40

60

80

100

Bud

brea

k (

)

P lt 0001n = 1010 n = 1515

n = 021

(b)




3 Results







Journal of Botany 5


A B

B

AP lt 0001

00

20

40

60

80

100Av

erag

e dist

ance

(cm

)

(a)




P = 0006

0

2

4

6

8

10

Freq

uenc

y

42 31 5 80 6 7Node

(b)


224



1

2

3

4

5

6

Aver

age n

umbe

r of s

tem

s

P = 0611


A

B

0

1

2

3

4

5

6

Aver

age n

umbe

r of s

tem

s

P = 0001

(b)




6 Journal of Botany


A

A

B

90

100

110

120

130

140

150Av

erag

e day

s to

first

flow

erP lt 0001


90

100

110

120

130

140

150

Aver

age d

ays t

o fir

st flo

wer

P = 0250

(b)


A

B

A

10

15

20

25

30

35

Aver

age d

ays r

ipen

ing

P = 0038


A

B

10

15

20

25

30

35

Aver

age d

ays r

ipen

ing

P = 0006

(d)


247



= 1401 119875 = 0258covariate 119865

147






246= 0057 119875 = 0945) The


146= 0004 119875 = 0949)




146=





146= 0261 119875 = 0612)


247=


Journal of Botany 7


10

20

30

40

50

60

70Fl

ower

ing

ram

ets (

)

n = 19

n = 11

n = 40

P lt 0001


0

10

20

30

40

50

60

70

Flow

erin

g ra

met

s (

)

n = 102

n = 108

P = 0403

(b)


10

20

30

40

Tota

l see

d he

ads p

rodu

ced

n = 24

n = 7

n = 16

P = 0010


0

10

20

30

40

Tota

l see

d he

ads p

rodu

ced n = 30

n = 17

P = 0080

(d)




247= 1401 119875 =


147= 0013 119875 = 0911)




247=


8 Journal of Botany


A

B

A

40

60

80

100

120Av

erag

e num

ber o

f see

dsP = 0019


A

B

40

60

80

100

120

Aver

age n

umbe

r of s

eeds

P = 0020

(b)


247



= 1223 119875 = 0305 covariate 119865147




247= 1223 119875 =


147= 2941 119875 = 0094)


247= 0856 119875 = 0433) with average


147=


247= 0060 119875 =


147= 1595 119875 = 0214) Seed


4 Discussion




Journal of Botany 9






5 Conclusion




Acknowledgments




References








































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology

Journal of Botany 5


A B

B

AP lt 0001

00

20

40

60

80

100Av

erag

e dist

ance

(cm

)

(a)




P = 0006

0

2

4

6

8

10

Freq

uenc

y

42 31 5 80 6 7Node

(b)


224



1

2

3

4

5

6

Aver

age n

umbe

r of s

tem

s

P = 0611


A

B

0

1

2

3

4

5

6

Aver

age n

umbe

r of s

tem

s

P = 0001

(b)




6 Journal of Botany


A

A

B

90

100

110

120

130

140

150Av

erag

e day

s to

first

flow

erP lt 0001


90

100

110

120

130

140

150

Aver

age d

ays t

o fir

st flo

wer

P = 0250

(b)


A

B

A

10

15

20

25

30

35

Aver

age d

ays r

ipen

ing

P = 0038


A

B

10

15

20

25

30

35

Aver

age d

ays r

ipen

ing

P = 0006

(d)


247



= 1401 119875 = 0258covariate 119865

147






246= 0057 119875 = 0945) The


146= 0004 119875 = 0949)




146=





146= 0261 119875 = 0612)


247=


Journal of Botany 7


10

20

30

40

50

60

70Fl

ower

ing

ram

ets (

)

n = 19

n = 11

n = 40

P lt 0001


0

10

20

30

40

50

60

70

Flow

erin

g ra

met

s (

)

n = 102

n = 108

P = 0403

(b)


10

20

30

40

Tota

l see

d he

ads p

rodu

ced

n = 24

n = 7

n = 16

P = 0010


0

10

20

30

40

Tota

l see

d he

ads p

rodu

ced n = 30

n = 17

P = 0080

(d)




247= 1401 119875 =


147= 0013 119875 = 0911)




247=


8 Journal of Botany


A

B

A

40

60

80

100

120Av

erag

e num

ber o

f see

dsP = 0019


A

B

40

60

80

100

120

Aver

age n

umbe

r of s

eeds

P = 0020

(b)


247



= 1223 119875 = 0305 covariate 119865147




247= 1223 119875 =


147= 2941 119875 = 0094)


247= 0856 119875 = 0433) with average


147=


247= 0060 119875 =


147= 1595 119875 = 0214) Seed


4 Discussion




Journal of Botany 9






5 Conclusion




Acknowledgments




References








































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology

6 Journal of Botany


A

A

B

90

100

110

120

130

140

150Av

erag

e day

s to

first

flow

erP lt 0001


90

100

110

120

130

140

150

Aver

age d

ays t

o fir

st flo

wer

P = 0250

(b)


A

B

A

10

15

20

25

30

35

Aver

age d

ays r

ipen

ing

P = 0038


A

B

10

15

20

25

30

35

Aver

age d

ays r

ipen

ing

P = 0006

(d)


247



= 1401 119875 = 0258covariate 119865

147






246= 0057 119875 = 0945) The


146= 0004 119875 = 0949)




146=





146= 0261 119875 = 0612)


247=


Journal of Botany 7


10

20

30

40

50

60

70Fl

ower

ing

ram

ets (

)

n = 19

n = 11

n = 40

P lt 0001


0

10

20

30

40

50

60

70

Flow

erin

g ra

met

s (

)

n = 102

n = 108

P = 0403

(b)


10

20

30

40

Tota

l see

d he

ads p

rodu

ced

n = 24

n = 7

n = 16

P = 0010


0

10

20

30

40

Tota

l see

d he

ads p

rodu

ced n = 30

n = 17

P = 0080

(d)




247= 1401 119875 =


147= 0013 119875 = 0911)




247=


8 Journal of Botany


A

B

A

40

60

80

100

120Av

erag

e num

ber o

f see

dsP = 0019


A

B

40

60

80

100

120

Aver

age n

umbe

r of s

eeds

P = 0020

(b)


247



= 1223 119875 = 0305 covariate 119865147




247= 1223 119875 =


147= 2941 119875 = 0094)


247= 0856 119875 = 0433) with average


147=


247= 0060 119875 =


147= 1595 119875 = 0214) Seed


4 Discussion




Journal of Botany 9






5 Conclusion




Acknowledgments




References








































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology

Journal of Botany 7


10

20

30

40

50

60

70Fl

ower

ing

ram

ets (

)

n = 19

n = 11

n = 40

P lt 0001


0

10

20

30

40

50

60

70

Flow

erin

g ra

met

s (

)

n = 102

n = 108

P = 0403

(b)


10

20

30

40

Tota

l see

d he

ads p

rodu

ced

n = 24

n = 7

n = 16

P = 0010


0

10

20

30

40

Tota

l see

d he

ads p

rodu

ced n = 30

n = 17

P = 0080

(d)




247= 1401 119875 =


147= 0013 119875 = 0911)




247=


8 Journal of Botany


A

B

A

40

60

80

100

120Av

erag

e num

ber o

f see

dsP = 0019


A

B

40

60

80

100

120

Aver

age n

umbe

r of s

eeds

P = 0020

(b)


247



= 1223 119875 = 0305 covariate 119865147




247= 1223 119875 =


147= 2941 119875 = 0094)


247= 0856 119875 = 0433) with average


147=


247= 0060 119875 =


147= 1595 119875 = 0214) Seed


4 Discussion




Journal of Botany 9






5 Conclusion




Acknowledgments




References








































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology

8 Journal of Botany


A

B

A

40

60

80

100

120Av

erag

e num

ber o

f see

dsP = 0019


A

B

40

60

80

100

120

Aver

age n

umbe

r of s

eeds

P = 0020

(b)


247



= 1223 119875 = 0305 covariate 119865147




247= 1223 119875 =


147= 2941 119875 = 0094)


247= 0856 119875 = 0433) with average


147=


247= 0060 119875 =


147= 1595 119875 = 0214) Seed


4 Discussion




Journal of Botany 9






5 Conclusion




Acknowledgments




References








































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology

Journal of Botany 9






5 Conclusion




Acknowledgments




References








































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology



References








































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology







































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology

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