Citrus Virus

8/12/2019 Citrus Virus

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Citrus VirusDiseases

Bill Dawson


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All graft-transmissible diseases initially were considered to be caused by viruses

Examples of changes Viroids

citrus exocortiscachexiaxyloporosis

Phytoplasmas, Spiroplasmasstubbornnew phytoplasma in Brazil that causes greening symptoms

Bacteriagreeningcitrus varigated chlorosis


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VIRAL DISEASES Citrus mosaic

Satsuma dwarf-related virus

Bud union creaseVirus for some combinations, otherwise genetic or unknownCitrus leaf rugose

genus Ilarvirus, Citrus leaf rugose virus (CLRV)Citrus yellow mosaic

genus BadnavirusCrinkly leaf

Crinkly leaf ilarvirus (strain of citrus variegation virus)Infectious variegation

genus Ilarvirus, Citrus variegation virus (CVV)Navel infectious mottling

Satsuma dwarf-related virusPsorosis

Spirovirus (ophiovirus) proposed new groupSatsuma dwarfSatsuma dwarf virus (SDV)

Tatter leaf = citrange stuntgenus Capillovirus, Citrus tatter leaf virus (probably a closely related strain of apple stemgrooving capillovirus rather than a distinct virus

Tristeza = decline and stem pitting, seedling yellows

genus Closterovirus, Citrus tristeza virus (CTV)

http://www.apsnet.org/online/common/names/citrus.asp


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VIROIDS AND GRAFT-TRANSMISSIBLE PATHOGENS (GTP)

Algerian navel orange virusGTP

Blight = young tree decline, rough lemon declineGTP

Blind pocketGTP

CachexiaCitrus cachexia viroid (Hostuviroid)

Chlorotic dwarfWhite-fly transmitted GTP

Citrus dwarfingVarios viroids

Citrus yellow mottleGTPCitrus yellow ringspot

GTPConcave gum

GTPCristacortis

GTPExocortis

Citrus exocortis viroid (CEVd) (Pospiviroid)Fatal yellows

GTPGummy bark

GTP, possible viroidGum pocket and gummy pittings

GTP, possible viroid

ImpietraturaGTP

Indian citrus ringspotGTP

Leaf curlGTP

Leathery leafGTP

LeprosisGTP associated with Brevipalpus spp. mites

Measls

GTPMilam stem-pittingGTP

Multiple sprouting diseaseGTP

Nagami kumquat diseaseGTP

Ringspot diseasesVarious GTPs

Vein enation = woody gallGTP (possible luteovirus)

Xyloporosis = cachexiaCitrus cachexia viroid (Hostuviroid)

Yellow veinGTP

Yellow vein clearing of lemonGTP


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Edited byJ.O. Whiteside, S.M. Garnsey, and L.W. Timmer

APS PressThe American Phytopathological Society

1988


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Endemic Viruses of Concern

Tatterleaf / Citrange Stunt

Infectious Variegation Citrus Leaf Rugose Psorosis complex

Citrus leaf blotch Citrus tristeza decline


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Tatter Leaf and Citrange Stunt virus complexlatent infections in Meyer lemonsapparently wide spread in China

Host Range and Symptomswhen infected cultivars are propagated on trifoliate or hybrids (Swingle

citrumelo, Carrizo, Troyer, and Kuharske citrange), trees arestunted and chlorotic, virus-induced incompability

can infect a wide range of citrus cultivars

causes mild symptoms if not on trifoliate rootstockcan infect a wild range of herbaceous hosts


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Tatter Leaf and Citrange Stunt virus complex continued

Causal Agentone positive-sense RNA

two subgenomic RNAs

Transmission and Epidemiology

graft transmitted by infected budwoodmechanically transmitted to a range of hoststhought to be aphid transmitted?

Identificationcharacteristic bud union creasingsymptoms on herbaceous hosts

Controlvirus-free budwood, difficult to removedecontaminate tools, knivesuse rootstocks other than Poncirus hybrids

A(n)ORF 1 CPORF 2

A(n)A(n)


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Wild type virus infected (8 dpi)Wild type virus infected (15 dpi)

Healthy


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Infectious Variegation Citrus Variegation Virus (CVV)

Host Range and Symptoms

can infect most citrus specieslemons, sour orange, citron, and grapefruit develop chlorotic leaf symptomsand distortion

mild strains exist that cause only mild mottle or chlorotic fleckingtrees can be stunted, some fruit may be distortedsymptoms are less in warm weather

can be mechanically transmitted to some cowpeas (chlorotic or necroticlesions and beans (chlorotic mottle or veinbanding)


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Infectious Variegation Citrus Variegation Virus (CVV) continued

Causal Agent

ilarvirus 4 positive-sense RNAs, sperical particlesCitrus crinkly leaf virus is a mild variant

Transmission and Epidemiologygrafting budwoodmechanically inoculateseed transmitted apparently rarepollen transmission?

Identificationindexing by graft inoculation to lemon or citronmechanical inoculation to cowpea or bean

Controlinfected budwood can be freed by thermotherapy or shoot tip graftingthen use virus-free budwood


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Leaf Rugose Citrus leaf rugose virus (CLRV)

Host Range and Symptomsinfects a broad range of citrus hostsMexican lime, Eureka lemon, and Duncan grapefruit develop leaf puckering,

pinpoint chlorotic spotting, and stuntingcan be mechanically transmitted to a range of noncitrus hosts


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Leaf Rugose Citrus leaf rugose virus (CLRV) continued

Causal agent

ilarvirus 4 positive-sense RNAs, isometric particles Transmission and Epidemiology

grafting and mechanical transmissionno vector known, but get some local spreadpollen?

Identificationindexing by grafting Eureka lemon or bush beanserology

Control

use virus-free budwooddecontamination of pruning tools


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Psorosis (psorosis A, mild; psorosis B, severe; concave gum; )probably a complex of several diseases, which share common symptomsusually found present in old-line trees

often bark scaling Host Range and Symptoms

symptoms stronger on young leaves ranging from chlorotic flecks, to leafmottling and chlorotic patterns

scaling and flaking of bark on the trunk and limbs of sweet orange and

grapefruit and occasionally mandarins -- usually not on other citruswood becomes impregnated with gumconcave gum thought to be related, mandarins and sweet oranges are

affected, deep concavities in the trunk and main branches


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Concave Gum Psorosis


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Psorosis (psorosis A, mild; psorosis B, severe) continued

Causal Agent

Transmission and Epidemiologygraft transmittedseed transmission rare

apparently some unknown vector Identification

field symptoms of bark scalingindexing by grafting to sweet orange or mandarin seedlings for leaf-flecking

Controluse virus-free budwood, use seed only from virus-free treescan use shoot-tip grafting or thermotherapydecontaminate tools


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Citrus ringspot virus (CRSV) Psorosis B

Host Range and Symptomsirregular spots or large, irregular chlorotic patterns on mature leavesfrequently gum impregnated and are slightly raised on the lower surfacefruit may have ringspotssome isolates are mechanically transmitted to Chenopodium spp


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Citrus ringspot virus (CRSV) Psorosis B continued

Causal Agentophiovirus, 3 negative-sense RNAs

very thin thread-like particlesnext slide has genome description

Transmission and Epidemiologygraft transmissiblemechanical transmissible

vector suspected but unknown

Controlvirus-free budwooddecontamination of tools


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The complete nucleotide sequence of a Spanishisolate

of Ci t ru s p so ros i s v i ru s : com para t ive ana lys i swith other ophioviruses

Brief ReportS. Mart

n1, C. L

opez2, M. L. Garc

a3, G. Naum -Ongan

a3, O. Grau3, R. Flores2, P. Moreno1, and J. Guerri1

Arch Virol (2005) 150: 167 176


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The virus induces two different syndromes: psorosis A (PsA), characterized by limited bark scalinglesions in the trunk and main limbs, and a more aggressive form of the disease called psorosis B (PsB)with rampant bark lesions affecting even thin branches and chlorotic blotches in old leaves. In thegreenhouse, the PsA and PsB syndromes can be induced by graft inoculating healthy citrus seedlingswith non-lesion or with lesion bark inoculum from PsA-affected field trees. PsA- and PsB-inducingCPsV sub-isolates obtained by this procedure from the same tree showed segments of the RNA 2enabled discrimination between PsA- and PsB-associated sequence variants. (i) PsA-inducing isolatescontain PsB-associated sequence variants at low frequency, (ii) the PsB-associated sequence variantis predominant in blistered twigs and gummy pustules affecting old leaves, characteristic of PsBisolates, and (iii) the PsB-associated sequence variant accumulates preferentially in bark lesions of thetrunk and limbs.

Association of citrus psorosis B symptomswith a sequence variant of the Citruspsorosis virus RNA 2 Velazquez, K

(Velazquez, K.)1; Pina, JA (Pina, J. A.)1;Navarro, L (Navarro, L.)1; Moreno, P(Moreno, P.)1; Guerri, J (Guerri, J.) PLANTPATHOLOGY 61 : 448-456


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Citrus leaf blotch virus (CLBV)

Host Range and Symptomsfirst found in kumquat on Troyer citrange rootstock with bud union

creaseSpain, France, Japan, Australia, Floridaassociated with abnormal bud unions on poncirus hybrid rootstocks

Causal Agent

filamentous particlesone positive-stranded RNA with 2 subgenomics

Transmission and Epidemiologyno known vectorseed transmitted

Controlvirus-free budwood

alternative rootstocks if necessary

p227 p40p41

Poly-A

Poly-A

Poly-A


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Citrus tristeza virus

Causes four disease syndromes:decline only on sour orange rootstocks

can be quick decline can be slowseedling yellows -- usually seen in greenhouse

on sour orange and grapefruitno disease mild strainsstem pitting on all rootstocks


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Department of Plant IndustryBudwood certification

Dr. Peggy Sieburth

Winter Haven

Budwood trees tested:Citrus tristeza virus decline isolate (MCA-13 positive) tested yearly

OK to have budwood with the mild isolate of CTVPsorosis and Concave gum tested once by biological indexing

now starting to test every 6 yearsCitrus leaf blotch virus (Dweet mottle virus) once every 6 years in budwood

source trees and also in seed source trees since it is seedtransmitted

Citrus tatter leaf virus will start test for next yearInfectious variegation virus is not tested for because it is mainly a problem for

lemons which are limited in Florida

Also test for viroids I, II, III, IV, V, and CEV every 6 years


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EXOTICVIRUSES


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Exotic Viruses of Concern Citrus chlorotic dwarf (CCD) Citrus yellow mosaic

Leprosis Satsuma Dwarf Tristeza stem pitting Vein enation Sudden death


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Vein Enation (Woody Gall)

important commercially only when severe galling occurs on youngtrees budded to rough lemon rootstocks

Host Range and Symptomsenations on the veins of Mexican lime, sour orange, and rough lemonswelling or galls on the stems of rough lemon and Mexican lime


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Vein Enation (Woody Gall) continued

Casual Agentspherical viruslike particles

Transmissiongraftingaphid transmitted Myzus persicae, Toxoptera, citricida, and Aphis

gossipiinot mechanically transmitted

Controlclean budwoodavoid use of rough lemon rootstocks


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Leprosis and Zonate Chlorosis

Host Range and Symptomsobserved primarily on sweet orange

sour orange and mandarins are also show symptomsother citrus normally do not show symptomssymptoms are chlorotic lesions, sometimes with a necrotic centerlater lesions become flat or raised necrotic areasleaves and fruit abscise when lesions are abundant, can get twig diebackcan mechanically transmit to Chenopodium spp


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Leprosis


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Leprosis and Zonate Chlorosis continued

Causal Agentcontroversy may be two different viruses causing similar diseases

rare nuclear form that is rod shaped and more prevalent cytoplasmic form ofbaciliform particles would be expected to be a rhabdoviruspositive-sense RNA virus with 2 RNAsvirus is a mite virus Brevipalpus spp. virus multiplies in mites

Transmission and Epidemiology

transmitted by mites -- millions of individual infectionsgraft transmitted with difficultyvirus does not move long distances, systemically

Controleliminate sources of inoculumcontrol mites, acaricides to reduce mite population


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Satsuma dwarf virus (SDV)

Host Range and Symptomswide host range in citrus

widely spread in Japanstunting and narrow, boat- or spoon-shaped leaves in satsuma mandarinChenopodium , cowpea, bean, Physalis , Gomphrena


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Satsuma dwarf virus (SDV) continued

Causal Agentsmall isometric virus with 2 RNAs

genome on next slide

Transmission and Epidemiologygraft transmitted by infected budwoodmechanically transmitted to herbaceous hostslocal spread, maybe a soilborne vector

Controlvirus-free budwood

Nucleotide sequences and taxonomy of satsuma dwarf virus


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q yToru Iwanami,1 Yoshiko Kondo1 and Alexander V. Karasev2

J Gen Virol. 1999 Mar;80 ( Pt 3):793-7.


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Citrus Sudden Deathnew disease reported in Brazil in 1999

Host Range and Symptomsdecline disease limited to Rangpur lime and to limited extent on

Volkamer lemon during periods of droughtrapid death of trees during droughtcharacteristic yellow stain at or below the bud union


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Citrus Sudden Death -- continued

Causal Agentsome controversy, a sobemovirus-like, marafivirus

but CTV associationgenome on next slide

Transmission and Epidemiologyspread looks similar to aphid transmission of CTV

no vector identifiedcan be grafted?

Identificationdecline determine whether on Rangpur lime or Volkamer lemonyellow stain at graft union

Controlvirus-free budwoodirrigationinarching

Identification and Genomic Characterization of a New Virus ( Tymovi r idae Family) Associated with Citrus Sudden DeathDi


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J Virol. 2005 Mar;79(5):3028-37.

DiseaseWalter Maccheroni, 1 Marcos C. Alegria, 1 Christian C. Greggio, 1 Joo Paulo Piazza, 1 Rachel F. Kamla, 1 Paula R. A. Zacharias, 1 Moshe Bar-Joseph, 1,

Elliot W. Kitajima, 2 Laura C. Assumpo, 1 Giovana Camarotte, 1 Jussara Cardozo, 1 Elaine C. Casagrande, 1 Fernanda Ferrari, 1 Sulamita F. Franco, 1 Poliana F. Giachetto, 1 Alessandra Girasol, 1 Hamilton Jordo Jr., 1 Vitor H. A. Silva, 1 Leonardo C. A. Souza, 1 Carlos I. Aguilar-Vildoso, 1 Almir S. Zanca, 1 Paulo Arruda, 1 Joo Paulo Kitajima, 1 Fernando C. Reinach, 1 Jesus A. Ferro, 1 and Ana C. R. da Silva 1*
http://jvi.asm.org/cgi/content/full/79/5/3028http://jvi.asm.org/cgi/content/full/79/5/3028http://jvi.asm.org/cgi/content/full/79/5/3028http://jvi.asm.org/cgi/content/full/79/5/3028


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Citrus Sudden Death

inarching


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Citrus yellow mosaic virusIndia, perhaps Japan

Host Range and Symptomsmosaic of leavesdoes not reduce fruit production, but fruit have less juice and ascorbic

acidwide citrus host range but apparently does not infect Mexican lime


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Citrus yellow mosaic virus

Causal Agentbadnavirus double-stranded circular DNA virus

Transmission and Epidemiologymechanically transmittedtransmitted by aphids or mealybugs?


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Citrus chlorotic dwarf virus (CCD)found in Turkey

Host Range and Symptomscauses crinkled and puckered leaves in lemon, tangelo, and sweet

orange

Transmission and Epidemiologytransmitted by the bayberry whitefly Parabemisia myricae

grafting of infected budwoodmechanically transmitted

Identificationcan do greenhouse experiments, but no simple identification

Control

CCD i l


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CCD in lemon

CCD in mandarin CCD in grapefruit

Id ifi i f i l d d DNA i i d i h i hl i


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Identification of a single-stranded DNA virus associated with citrus chloroticdwarf disease, a new member in the family Geminiviridae

Giuliana Loconsole a , Pasquale Saldarelli b, HarshavardhanDoddapaneni c, Vito Savino a, b , Giovanni P. Martelli a, b , Maria Saponari b,Virology 432: 162-172 (2012)


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Citrus Tristeza Virus (CTV) Decline

Host Range and Symptomscan infect most citrus varieties and relativesPoncirus spp are resistant to most isolatesdisease is limited to scions on sour orange rootstocks


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Roots of declining tree no feeder roots


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g


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Citrus tristeza virus decline

Causal Agentpositive-stranded RNA virus ~ 20,000 nts

PRO

HSP70 p23 p13

p18 p20

p27

p61 p6

PRO

CP p33

RdRp

HEL MT


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p27 (minor capsid protein, CPm) p25 (major capsid protein, CP)

From: Tian et al. J. Gen.Virol.80:1111 (1999)

Gold-labeled CPantiserum

Gold-labeled CPmantiserum

CTV virions


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p6

p23 p20 p13 p18 CP CPm p61

p33 Polyprotein: Replicase

p18 p20

RdRp

PRO PROMT

p13

HSP70h CPm

p61p6 CP

p33

p23

HEL

ORF 1a 1b 2 3 4 5 6 7 8 9 10 11

IDR

RdRp +1 Ribosomal frameshift:

3

probe5

probe

Proteins

Citrus tristeza virus

HSP70h

( )

( )

( )

( )

( )

( )

( )

( )

( )

( )


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Citrus tristeza virus (CTV) decline

Transmission and Epidemiologyaphid transmitted by a series of aphids, brown citrus aphid best

also melon, cotton aphidstransmitted in a semi-persistent manner ~ 1 hr to ~ 24 hr

Identificationin field, identify rootstock sour orange

bud union staining, scion overgrowth, thickened bark at unionserology can detect CTV; can differentiate FL mild from declinebiological assay in greenhouse

vein clearing and leaf cupping in Mexican lime

Controluse alternative rootstockuse virus-free or decline-free budwood


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Citrus tristeza virus (CTV) stem pitting

no severe stem pitting isolates of CTV known to be in Floridaevery effort is being made to keep them out

Host Range and Symptomsstem pitting does not kill treesreduces vigor, reduces growth, reduces yield and fruit sizestem pitting is specific to virus isolate and host

some isolates cause stem pitting in grapefruitsome isolates cause stem pitting in sweet orangesome isolates cause stem pitting in bothmandarins are more tolerant

Control

keep stem pitting isolates outmild strain cross protection


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FS674

on DG

Risk evaluation of exotic pathogens for citrus


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Disease Impact Intro Estab Spread Estab m Estab F Detection Control factor 1 factor 2 4factRel % 6factRel%

HLB 10 7 7.1 7 7.03 347.90 2.6 10 1828.7 90454.0 100.00% 100.00%

Blackspot 5.8 6.2 8.7 10 8.30 539.40 3.3 6.9 1096.1 71236.4 59.94% 78.75%

CTV-SP 6.1 5.8 9.8 9.1 8.23 517.24 2.5 5.5 690.6 43383.8 37.76% 47.96%

Canker 7.9 10 7.7 10 9.23 770.00 1 3.5 255.3 21290.5 13.96% 23.54%

CVC 7 4.1 10 7.8 7.30 319.80 0.9 8.4 386.3 16923.8 21.13% 18.71%

Phaeoram 5.2 3.2 6.8 9.3 6.43 202.37 2 7.2 481.7 15153.3 26.34% 16.75%

CCD 1.9 2.9 5.1 4.3 4.10 63.60 10 7.1 553.1 8579.2 30.24% 9.48%

Leprosis 2.4 4.2 3.8 3.6 3.87 57.46 4 3.5 129.9 1930.5 7.10% 2.13%

Swt. Scab 1.2 2.7 4.7 4.7 4.03 59.64 1.6 3.2 24.8 366.4 1.36% 0.41%

Vein Enation 0.2 3.1 4.7 7.9 5.23 115.10 2.5 3.6 9.4 207.2 0.52% 0.23%

SDV 0.8 2.6 4.1 3.8 3.50 40.51 1.2 4.8 16.1 186.7 0.88% 0.21%

CYM 1.9 2.1 4.1 3.1 3.10 26.69 1 2.6 15.3 131.9 0.84% 0.15%

ACD 0.2 1.3 2.1 2.4 1.93 6.55 9 8.9 31.0 105.0 1.69% 0.12%

Stubborn 1 4.2 2.1 3.8 3.37 33.52 0.6 4.9 9.9 98.5 0.54% 0.11%

Pow. Mil 0.6 1.3 2.3 4 2.53 11.96 0.8 2.7 3.3 15.5 0.18% 0.02%

LWB 0.7 1.3 1.8 1.9 1.67 4.45 1.7 1.9 3.8 10.1 0.21% 0.01%

Mal Secco 0.4 2.1 1.1 1.8 1.67 4.16 1.3 1.5 1.3 3.2 0.07% 0.00%

Risk evaluation of exotic pathogens for citrus


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Mild strain cross protection

Purposely inoculate trees with a mild strain of the virus to prevent infection bysevere stem pitting isolate

Common practice in Brazil, South Africa, Australia

How does cross protection work?different strains of CTV do not cross protect against each othermust find a mild strain that has close sequence to the severe strain

otherwise must make one


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ORF 1a 1b 2 3 4 5 6 7 8 9 10 11

p18 p20

RdRp

L1 L2

MT

p13

HSP70h CPm

p61 p6 CP

p33

p23

HELIDR

CTV-based expression vector

Green fluorescent protein

from jellyfish

CPm CP

gfp p18 p20

p13 p23RdRp

L1 L2

MT

HSP70h

p61 p6

p33

HELIDR


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DIFFERENTIAL SUSCEPTIBILITY OF DIFFERENT HOSTS TO T36


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ML CM MV SO DG

1 mm

DIFFERENTIAL SUSCEPTIBILITY OF DIFFERENT HOSTS TO T36


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C mac So Orange

N i i GFP i T36 i b d i


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No protection against GFP-expressing T36 strain-based virus:

T68-1 T3 T30 VT

T36

Protection

FS 703 protection


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FS 703 protection

FS672 challenge

No protection

FS672 challenge


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FS 703 protection

FS701 challenge

No protectionFS701 challenge


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What about CTV decline?

Have to have a mild isolate of the T36 strain Probably does not exist in Florida Then have to make one


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PRO

HSP70 p23 p13

p18 p20

p27

p61 p6 PRO

CP p33

RdRp HEL MT

PRO

HSP70 p23 p13

p18 p20

p27

p61 p6 PRO

CP p33

RdRp HEL MT

decline

mild

Florida CTV strains

Genetic system for CTV


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y

dsRNA

cDNA

Bacteria

in v i t ro transcription virusRNA

Protoplast

Virus particles

CTV Infectedtree Healthy seedling


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Healthy

rCTV-T36

WT CTV-T36

Seedling yellows reactionon sour orange plants


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T36/T30 hybrids

3

p18 p20

RdRp p13

HSP70h CPm

p61 p6 CP

p33

p23

3

p18 p20

RdRp p13

HSP70h CPm

p61 p6 CP

p33

p23

3

p18 p20

RdRp p13

HSP70h CPm

p61 p6 CP

p33

p23

3

p18 p20

RdRp p13

HSP70h CPm

p61 p6 CP

p33

p23

3

p18 p20

RdRp p13

HSP70h CPm

p61 p6 CP

p33

p23

3

p18 p20

RdRp p13

HSP70h CPm

p61 p6 CP

p33

p23


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PRO

HSP70 p23 p13

p18 p20

p27

p61 p6 PRO

CP p33

RdRp HEL MT

PRO

HSP70 p23 p13

p18 p20

p27

p61 p6 PRO

CP p33

RdRp HEL MT

PRO

HSP70 p23 p13

p18 p20

p27

p61 p6 PRO

CP p33

RdRp HEL MT

*decline

mild

hybrid

SY

-

-


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Healthy

T30

T36

P23+NTR of

T30 in T36

P65+p61 of T30Sour Orange

Substitution of p23 gene + NTR of T30 into genome of T36 creates


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p g gcross-protecting isolate against seedling yellows

T36-infected sour orange

Healthy sour orange

In the center p23+NTR-T30/T36 hybrid-infected sour orange, later challenged with T36


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field test to protect citrus

on sour orange rootstocks

Citrus Virus

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