ARTICLE IN PRESS

Journal of Plant Physiology 163 (2006) 228—230

www.elsevier.de/jplph

BOOK REVIEWS

K. Lindsey (Ed.), Polarity in Plants, BlackwellPublishing, CRC Press, Oxford, UK, ISBN 1-40511-432-0, 2004 (346pp., price USD 99.50).

The establishment of cell polarity plays a centralrole in various developmental processes. Often,directional secretion, signal transduction and lo-cally restricted growth processes are based on cellpolarity. In many cases, cell polarity is alsoimportant for asymmetric cell divisions, which inturn lead to different cell fates of the two daughtercells. During recent years, it has been shown thatthe molecular mechanisms involved in the estab-lishment and further processing of cell polarity areconserved from unicellular organisms to higherplants and animals.

This book aims at reviewing essential aspects ofdifferent levels of polarity of plants, from thepolarity of the single cell to the polarity of thewhole organism, in order to bring together thediverse aspects of polarity in plant development. Itis divided into 11 chapters written by authors fromleading laboratories involved intensively in studiesconcerning different aspects of polarity in cells. Ingeneral, each chapter gives quite a good summaryof the state of the field. Chapter 1 represents anoverview of the polar cell growth and the functionof the cytoskeleton, including the role of cytoske-leton in cell expansion, with a precise descriptionof the different components of the cytoskeleton.Chapter 2 entitled ‘‘Mechanisms of cell polarityestablishment and polar auxin transport’’ predomi-nantly provides information on cell polarity of the‘‘model plant cells’’ root hairs of Arabidopsis andshows clearly that the direction of auxin transportis determined by the polar distribution of transportproteins and secretion systems. The third chaptergives an overview of cell walls as the most criticalcomponents of plant cells in connection with theirpolarity, and found that plant cells control thecomposition on wall domains via both targetedexocytosis and local endocytosis. Chapter 4 reviewsthe current knowledge of the polarity in single cellsas in trichomes, epidermal pavement cells and roothairs and shows again intensively the critical role ofcytoskeleton elements in regulating cell polarity. InChapter 5, the author deals with the development

in fucoid algae by using the model system Fucus,which provides excellent systems for studying thepolarity mechanisms in plants and algae. For thesesystems, targeted knock-out and overexpressionstudies are lacking to date. Chapter 6 providesspecial aspects of plant embryogenesis that arelinked to polarity and cell fate specification ofArabidopsis. It is suggested that the cell divisionplane alone is not instrumental in the determina-tion of polarity and its perturbation is not sufficientto break down. In Chapter 7, important aspects ofpolarity in relation to primary tissues of roots, aswell as the current knowledge of secondary polarityof secondary meristems in roots are discussed, andit is shown that signalling gradients of auxin aregenerated, which define cell identity and pattern inindividual organs. The following Chapter 8 dealswith questions about the development of the shootapical meristem, and discusses intensively the roleof KNOX class homeobox genes and the interactingtranscription factors in connection with the im-portance of interregional communication betweenthe meristem and the organ primordia. A furtherpoint of view is the cell communication along theapical–basis axis and the regulation of stem cellnumber. In Chapter 9 the authors describe polarsignals in vascular development and provide anexcellent overview over genes involved in vascularstrand formation in different plant species. Thereview in chapter 10 represents an overview ofpolarity in leaves and leaf-like organs that areproduced from the flanks of the apical meristemsand focuses on the adaxial–abaxial axis especiallyof seed plants. Finally, Chapter 11 provides dataconcerning the regulation of polarity at differentlevels of flower development in two model species,Arabidopsis thaliana and Antirrhinum majus, andthe results show similarities to the establishment ofleaf polarity.

Overall, this valuable book is recommended forscientists in fundamental and applied research, asit provides fast access to a collection of importantdevelopments concerning polarity in plants. Ingeneral, the authors have managed to incorporatethe most recent approaches, data and models,while avoiding preliminary results and excessdetail on a vast literature of original and review

ARTICLE IN PRESS

BOOK REVIEWS 229

papers. The book is nicely illustrated, with alarge number of excellent, original drawings andphotographs, and gives a splendid overview of thestate of the field.

Maria MullerInstitute of Plant Sciences, University of Graz,

Graz A-8010, AustriaE-mail address: maria.mueller@uni-graz.at

doi:10.1016/j.jplph.2005.07.003

M.A. Bacon (Ed.), Water Use Efficiency in PlantBiology, Blackwell, Oxford, UK, ISBN 1-4051-1434-7, 2004 (344pp., GBP 99.50).

The UN Food and Agriculture Organisation esti-mates that in order to feed a growing worldpopulation with changing consumption, food pro-duction will have to increase by about 60% until2030. Since we can not expect the cultivated landto increase by such a factor, the increase inproduction will have to come primarily from higherproductivity, and with water being a scarceresource and the main limit to crop production inmany places, through improved water manage-ment, which is summarized in the catchphrase of‘‘more crop per drop’’. Thus, the need to improvewater use efficiency (WUE) of crops, and to under-stand how it is affected is urgent, and this bookprovides a very useful review of current knowledge.In principle, achieving higher WUE is quite easy.Forcing plants to close their stomata will, unlesscarboxylation is impaired, result in a steepergradient of CO2 across the stomata at the samemoisture gradient, and consequently, more CO2

uptake per water lost. Unfortunately, this alsoresults in reduced CO2 uptake and crop growth, butfortunately, the physiology of water loss, photo-synthesis and growth is much more complex, andprovides ample possibilities to improve WUE alsowithout reducing production, and this book does anexcellent job in explaining these relationships.

There are several ways of defining water useefficiency, from the short-term gas exchange on aleaf basis (moles of CO2 absorbed per mol of H2Olost through transpiration) to the perspective of anagronomist, who is more interested in the relation-ship between the amount of irrigation waterapplied and the biomass harvested. Most authorsof the various chapters start defining WUE for theparticular context of their discussion. It may havebeen more succinct to explain the various defini-tions in an introductory chapter, but perhaps thesubsequent parts would have then been difficult toread as stand-alone publications without alwaysreferring to the introduction.

Chapter 1 sets the scene and gives a shortintroduction and an overview of the physiologicalfactors affecting WUE. Chapter 2 provides some

definitions of WUE and explains the relationshipbetween gas exchange, atmospheric vapour pres-sure deficit and WUE. For instance, because densecanopies affect the microclimate of the leaf andtranspiration is more decoupled from the atmo-sphere than CO2 uptake, changes in stomatalconductance may not translate to changes in WUEas predicted. Chapter 3 explains the trade-offsbetween water loss, CO2 concentration and uptake,and nutrient availability, and the differences inWUE (as indicated by carbon isotope ratios) foundin natural vegetation. Chapter 4 discusses thevarious chemical signals involved in the responseof stomatal regulation and leaf growth to variousstresses and particularly dwells on the effects ofand interrelations between ABA and apoplastic pH.Regulated deficit irrigation and partial root dryingare two techniques that have been successfullyapplied to increase WUE or fruit quality in variouscrops using our understanding of chemical signal-ling and a plant’s possibility to regulate WUE(Chapter 5). Chapter 6 focuses on agronomicapproaches, defining WUE mostly as transpirationefficiency (biomass produced per transpired water)and shows that crop and genotype can affect WUEas well as mulching, tillage, rapid canopy develop-ment or crop spacing. Since photosynthesis is notonly determined by CO2 supply but also bybiochemical reactions, it is clear that nutrientsupply, particularly nitrogen, will also affect CO2

uptake and hence WUE (Chapter 7). Crop produc-tion is not really about total plant biomass, butabout the biomass used, and the proportion ofbiomass harvested (the harvest index) is affectedby grain filling during senescence, which can bemanipulated in various ways as shown for rice andwheat in Chapter 8. Chapter 9 discusses molecularapproaches from unravelling the genetic basis ofWUE to modifying plants through genetic engineer-ing. Many physiological indices of WUE have beenlinked to genetic variation by analysing quantita-tive trait loci; some of these have been used formarker-assisted selection and breeding, and asubstantial number have already been pinned downto individual genes responsible for drought toler-ance and WUE.

There are a few errors that escaped proof-reading. For example, in Formula 2.2. (p. 34) the