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Phylogenetic analysis and association mapping for agronomic and quality traits in USDA pea PSP collection
P. CHENG (1), W. Holdsworth (2), Y. Ma (1), M. Mazourek (2), M. Grusak (3), C. Coyne (1), R. McGee (1). (1) Washington State Univ, Pullman, WA, U.S.A.; (2) Cornell University, Ithaca, NY, U.S.A.; (3) USDA-ARS Children's Nutrition Research Center, Houston, TX, U.S.A.

Association mapping is an efficient approach for the identification of the molecular basis of agronomic traits in crop plants. For this purpose, we genotyped and phenotyped individual lines of the USDA pea <i>Pisum</i> single-plant (PSP) collection including accessions from 327 landraces and cultivars of <i>Pisum sativum</i>, 26 <i>P</i>. <i>sativum</i> subsp. <i>elatius</i>, 16 <i>P</i>. <i>sativum</i> var. <i>arvense</i>, 4 <i>P</i>. <i>sativum</i> var. <i>pumilio</i>, 3 <i>P</i>. <i>sativum</i> subsp. <i>asiaticum</i>, 3 <i>P</i>. <i>abyssinicum</i>, 2 <i>P</i>. <i>fulvum</i>, 2 <i>Pisum</i> spp., and 1 <i>P</i>. <i>sativum</i> subsp. <i>transcaucasicum.</i> These 384 accessions were collected from a total of 64 countries. The accessions were genotyped with 256 informative SNPs using Sequenom MassARRAY. Genetic structure analysis showed that the population was structured into two main groups, corresponding roughly to the cultivated types/landraces and the wild subspecies, with some intermediates. Linkage disequilibrium (LD) of pairwise loci was analyzed. Association analysis between SNP genotypes and 37 valuable traits such as disease resistance, morphological traits, carbohydrate content, and mineral nutrient concentration were performed using a mixed linear model. A total of 123 marker trait associations (MTAs) were detected to be significant with 1-9 markers per trait. Some of these gene-anchored SNP markers revealed candidate genes and confirmed quantitative trait loci that have been identified previously. This study showed the potential of using association mapping in pea breeding.

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