Outline placeholderReferencesWhy are there so many carbohydrate-active enzyme-related genes in plants?Content of genomes in carbohydrate-active enzyme-related genesOrigins of the multiplicity of carbohydrate-active enzyme-related genes in plantsAcknowledgementsReferencesUnraveling the functions of glycosyltransferase family 47 in plantsExostosins and family GT47decade, has mobilized a partnership of private andpublic research groups to focus on the development ofnew technologies to support T. cacao genetic improve-ment (http://www.ars-grin.gov/ars/SoAtlantic/Miami/ngr/cacao_genetics_meeting_summary.pdf) with a degree ofcoordination by the International Group for GeneticImprovement of Cocoa (INGENIC), which promotes theexchange of information and international collaborationon topics related to cocoa genetics. This initiative comes ata time of unprecedented new genomic tools that dramati-cally increase the genetic knowledge to inform breedingstrategies and to accelerate notoriously slow tree breedingprograms. Over the next decade, T. cacao is likely tobecome a model of an essentially wild crop being trans-formed through genome-based breeding. It will be inter-esting to see whether these new tools can provide the basissimultaneously to address the improvement of cocoa pro-ductivity while maintaining the quality characteristics ofthe bean that are crucial for chocolate production.References1 Dillinger, T.L. et al. (2000) Foods of the gods: cure for humanity?A cultural history of the medicinal and ritual uses of chocolate. J. Nutr.130, 2057S –2072S2 Kris-Etherton, P.M. and Keen, C.L. (2002) Evidence that the anti-oxidant flavonoids in tea and cocoa are beneficial for cardiovascularhealth. Curr. Opin. Lipidology 13, 41 –493 Eskes, B. (2001) Introductory notes. 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(2000) Quantitative trait loci analysis inTheobroma cacao using molecular markers: inheritance of polygeneticresistance to Phytophthora palmivora in two related cacao popu-lations. Euphytica 114, 25– 3612 Flament, M-H. et al. (2001) Genetic mapping of resistance factors toPhytopthora palmivora in cocoa. Genome 44, 79– 8513 Queiroz, V.T. et al. (2003) Identification of a major QTL in cocoa(Theobroma cacao L.) associated with resistance to witches’ broomdisease. Plant Breed. 122, 268– 27214 Lanaud, C. et al. (2001) Implications of new insight into thegenetic structure of Theobroma cacao L. for breeding strategies.Proceedings of the International Workshop on New Technologies forCocoa Breeding, Kota Kinabalu, Malaysia, INGENIC, London, UK,pp. 89 – 10715 Saunders, J.A. et al. (2001) USDA DNA fingerprinting programfor identification of Theobroma cacao accessions. Proceedings ofthe International Workshop on New Technologies for Cocoa Breeding,Kota Kinabalu, Malaysia, INGENIC, London, UK, pp. 108– 11416 Jones, P.G. et al. (2002) Gene discovery and microarray analysis ofcacao (Theobroma cacao L.) varieties. Planta 216, 255–2641360-1385/$ - see front matter q 2003 Elsevier Ltd. All rights reserved.doi:10.1016/j.tplants.2003.10.004Why are there so many carbohydrate-activeenzyme-related genes in plants?Pedro M. Coutinho, Mark Stam, Eric Blanc and Bernard HenrissatArchitecture et Fonction des Macromole´ cules Biologiques, UMR 6098, Centre National de la Recherche Scientifique,Universite´ s Aix-Marseille I and II, 31 Chemin Joseph Aiguier, 13402 Marseille cedex 20, FrancePlants contain far more carbohydrate-active enzyme-encoding genes than any other organism sequenced todate. The extremely large number of glycosidase andglycosyltransferase-related genes in plant genomes canbe explained by the complex structure of the plant cellwall, by ancient genome duplication and by recent localduplications, but also by the recent emergence of noveland unrelated protein functions based on widely avail-able pre-existing scaffolds.In plants, carbohydrates in the form of glycosides arecentral to many biological pathways, from cell wallstructure to energy, signalling and defence. Glycosidesare made from activated sugars by glycosyltransferasesand are degraded by glycoside hydrolases (glycosidases).Genes encoding glycosidases and glycosyltransferases inall organisms (all data available from the Carbohydrate-Active enZymes server at http://afmb.cnrs-mrs.fr/CAZY/)are currently analysed and listed based on the classifi-cations of glycosidases [1] and glycosyltransferases [2] insequence- and structure-based families. Now that thegenomes of many organisms have been completelysequenced, it is possible to analyse the content of genomesfrom a global glycobiological perspective.Content of genomes in carbohydrate-activeenzyme-related genesOne of the intriguing features of the analysis of thesequenced genomes is that for bacteria and for eukaryotesthere appears to be a global correlation between the numberof glycosidase and glycosyltransferase-related genes and theCorresponding author: Bernard Henrissat ([email protected]).Update TRENDS in Plant Science Vol.8 No.12 December 2003563http://plants.trends.comtotal numberof genes in the organism (Figure 1). The archaeado not show such a correlation and it is likely that many (if notall) of their glycosidases have been acquired by horizontaltransfer (i.e. by transfer of genetic material betweenorganisms other than by descent). Figure 1 shows thatArabidopsis is a clear outlier with almost 800 glycosidase andglycosyltransferase-related genes comprising . 3.3% of itsgenes [3]. By comparison, the human genome has only, 350 glycosidase and glycosyltransferase-related genes.Origins of the