An SSR Cluster Analysis On Tibetan Brassica Rapa Resources

Rapeseed, one of the world’s four major oil crops (soybean, sunflower, peanut, rapeseed),belongs toBrassica in the family of Brassicaceae. In accordance with its botanical properties and its biologicalfeatures and properties, rapeseed can be divided into three categories: Brassica napus, Brassica rapa andBrassica juncea. Brassica rapa is one of the three major categories of rapeseeds that are widelycultivated in the world, which constitutes a very wide range of genetic variations. Tibet,as an origin ofBrassica rapa, possesses a relatively rich rapeseed resources, where Brassica rapa is one of the oil cropsthat are most widely distributed and cover the largest areas. Brassica rapa is cultivated in an enormousarea, adjacent to Kangdese Mountains–Nyenchen tanglha Mountains in the north, the Himalayas in thesouth, Jinsha River in the east, and Ngari highland in the west. Meanwhile, there is a tendency showingthat the cultivation area of Brassica rapa are gradually increasing from the north and south sides to themiddle region. Neverthless, no documents and studies have been found, concerning the germplasmresources and the genetic diversity of Brassica rapa.This experiment selected169samples of Brassica rapa resources, whose process include: recordingthe phenological periods and agronomic traits of each sample, analyzing the genetic diversity amongstthese169Tibet between Brassica rapa samples through SSR markers, specifying the geneticbackground and the degree of similarity of these materials, and on the basis of this series of data,evaluating the genetic diversity of germplasm resources within these Tibet Brassica rapa samples.According to the results, it can be concluded that23pairs of primers have amplified80bands in all,with an average of3.5bands/primer pair, the size of which is between50-400bp; in accordance with thesimilarity coefficients being0.5,0.53,0.56,0.59,0.62and0.70, the materials applied in the experimentcan be divided into2,4,6,9,14and29types. The clustering results drawn from molecular markers canonly provide an initially prediction of the genetic relationship between these rapeseeds, and informationon the origins and differentiation states of these materials requires further studies relating with themorphology and geographical distribution of these materials.