Phenotypic Diversity and Association Mapping for Pea Quality Traits in Landrace Pea and Related Species.

Association mapping has been proposed as an efficient approach to assist in the identification of the molecular basis of agronomical traits in plants. For this purpose, we analyzed the phenotypic and genetic diversity of a large collection of the single plant derived core of the USDA Pisum germplasm collection including 316 landraces and cultivars (Pisum sativum), 26 P. sativum  subsp. elatius, 16 P. sativum var. arvense, 11 P. sativum  subsp. sativum, 4 P. sativum var. pumilio, 3 P. sativum subsp. asiaticum, 3 P. abyssinicum, 2 P. fulvum, 2 Pisum spp., and 1 P. sativum subsp. transcaucasicum,  accessions from 64 countries. The accessions were genotyped using an iPLEX assay of 363 published SNPs, among which 342 were informative for subsequent analysis. Linkage disequilibrium (LD) of pairwise loci and population structure were analyszed, and the association analysis between SNP genotypes and a few valuable traits such as disease, seed weigh/size, flower color, carbohydrate content, mineral nutrients and protein will be reported using a mixed linear model. Genetic structure analysis showed that the population was structured into three main groups. Interestingly, the three groups were corresponded to neither the taxon nor the country of origin. This study will show the potential and limits of using association mapping in pea populations.