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Genetic Diversity, Population Structure, Parentage Analysis, and Construction of Core Collections in the French Apple Germplasm Based on SSR Markers
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Edité par CCSD ; Springer Verlag -
In-depth characterization of apple genetic resourcesis a prerequisite for genetic improvement and for germplasmmanagement. In this study, we fingerprinted a very largeFrench collection of 2163 accessions with 24 SSR markersin order to evaluate its genetic diversity, population structure,and genetic relationships, to link these features with cultivarselection date or usage (old or modern, dessert or cider cultivars),and to construct core collections. Most markers werehighly discriminating and powerful for varietal identification,with a probability of identity P(ID) over the 21 retained SSRloci close to 10−28. Pairwise comparisons revealed 34 % redundancyand 18.5 % putative triploids. The results showedthat the germplasm is highly diverse with an expected heterozygosityHe of 0.82 and observed heterozygosity Ho of 0.83.A Bayesian model-based clustering approach revealed a weakbut significant structure in three subgroups (FST=0.014–0.048) corresponding, albeit approximately, to the three subpopulationsdefined beforehand (Old Dessert, Old Cider, andModern Cultivars). Parentage analyses established alreadyknown and yet unknown relationships, notably between oldcultivars, with the frequent occurrence of cultivars such asBKing of Pippin^ and BCalville Rouge d’Hiver^ as founders.Finally, core collections based on allelic diversity were constructed.A large dessert core collection of 278 cultivarscontained 90 % of the total dessert allelic diversity, whereasa dessert subcore collection of 48 cultivars contained 71 % ofdiversity. For cider apples, a 48-cultivar core collectioncontained 83 % of the total cider allelic diversity.
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