Genetic Diversity And Population Structure Of Pea And Its Closely Related Species Based On Morphological Traits And Genomic SSR Markers

Pea(Pisum sativum L.)is an important food legume crop grown widely throughout the world for humans consumption or livestockfeeding.Despite extensive studies,the genetic structure and classification of pea and its closely related wild species under genus Pisum are still controversial at global scale due to incomplete sampling or limited numbers of markers.To lay an important foundation for understanding the domestication process and promoting breeding utilization of pea,33 morphological traits and 87 genome-wide polymorphic SSR markers were utilized in present study to conduct a comprehensive population genetic and morphological variation analyses at different hierarchical levels to a total of 323 accessions pea germplasm,including Chinese and world-wide cultivated core collections as well as closely related wild species.Main results of this research are as follows:1.Through a population genetic study of 323 accessions pea germplasm and its closely related species including eight taxa within Pisum,Chinese core collection and world-wide pea germplasm,all the tested accessions can be divided into three different genetic groups.Among these three genetic groups,group 1 was mainly composed of the wild species P.fulvum(PF),the Ethiopian pea P.abyssinicum(PA)and some wild types of cultivated pea P.sativum(PS ?),while group 2(PS ?)and group 3(PS ?)were two cultivated groups within P.sativum.PS ? was mainly composed of Chinese cultivated pea germplasm resources(81%),while PS ? was mainly composed of foreign cultivated germplasm resources of pea(90%).We calculated the genetic diversity of each species and subgroups of PS,which suggested that PF has the highest genetic diversity,the subgroups of PS retain appropriate genetic diversity and PA has the lowest genetic diversity.Morphological variation studies showed that:An obvious morphological differences were found between the wild species PF and the cultivated groups including PS ? and PS ?;The Ethiopia pea PA showed some unique morphological characteristics;PS ? with wild genetic background seemed like a transitional type in morphology;little morphological difference were observed between cultivated groups PS ? and PS ?.2.A population genetic study of 138 germplasms with specific classification name belong to eight taxa within Pisum identified three genetic groups which generally correspond to the three species P.fulvum,P.abyssinicum and P.sativum under genus Pisum.In addition,further division of subgroups under the species P.sativum was not supported by the molecular and morphological evidence.Several samples of P.s.elatius similar to the wild species P.fulvum should be excluded from P.sativum.In addition,this study proves once again that P.fulvum is a distinct wild species and supports that P.abyssinicum is an independent species.It is suggested that P.fulvum has the highest genetic diversity;P.s.elatius,P.s.pumilio and P.s.asiaticum with some content of wild genetic background retain appropriate genetic diversity;while P.abyssinicum has the lowest genetic diversity.Morphological analysis divided eight taxa within Pisum into three main groups.P.fulvum and P.abyssinicum were grouped separately,while the other samples were not subdivided according to taxonomy name butmixed into a cultivated pea group.3.Through a molecular population genetic study,142 accessions Chinese pea germplasm can be firstly divided into two genetic groups,PS-CHN1 and PS-CHN2,and the genetic diversity of PS-CHN1 is actually lower than that of PS-CHN2,which are corresponding to the above mentioned two cultivated genetic groups,PS ? and PS ?,respectively.Meanwhile,samples within each genetic groups,can be roughly divided into two ecotypes associated with spring sowing and autumn sowing.Morphologically,there was no obvious differentiation between the two genetic groups nor between the two ecotypes of spring sowing and autumn sowing.