Population genetic structure and classification of cultivated and wild pea (Pisum sp.) based on morphological traits and SSR markers

<p>Pea (<em>Pisum</em> <em>sativum</em> L.) is an important legume crop that is widely grown worldwide for human consumption and livestock feed. Despite extensive studies, the population genetic structure and classification of cultivated and wild pea (<em>Pisum</em> sp.) are remaining controversial. To characterize patterns of genetic and morphological variation and investigate the classification of <em>Pisum</em>, we conducted comprehensive population genetic analyses for 323 accessions from cultivated and wild pea representing three species of <em>Pisum</em> utilizing 34 morphological traits and 87 polymorphic SSR markers. First, we identified three distinct genetic groups among all samples. Group I was primarily composed of <em>Pisum fulvum</em>, <em>Pisum</em> <em>abyssinicum</em> and some wild <em>P. sativum</em> accessions, whereas groups II and III consisted of the two genetic groups under <em>P. sativum </em>representing different geographic distributions of cultivated pea. Analyses of morphological variation revealed significant differences among the three species. Second, among pea germplasms representing eight taxa of <em>Pisum</em>, <em>P. fulvum</em> and <em>P. abyssinicum</em> possessed unique genetic backgrounds and morphological characteristics, corroborating their independent species status. The intraspecific subdivisions of <em>P. sativum</em> described by some authors were not supported in this study, with the exception of several genotypes of <em>P. sativum</em> subsp. <em>elatius</em> that were clustered with <em>P. fulvum</em> and <em>P. abyssinicum</em>. Finally, we confirmed that the Chinese pea germplasm was genetically distinct and could be divided into two genetic groups, each of which included both spring-sowing and autumn-sowing ecotypes. These results provide a robust foundation for understanding pea domestication and the utilization of wild genetic resources of pea.</p>