Evaluation Of The Genetic Diversity Of Some Chinese Double Low (Low Erucic Acid And Low Glucosinolates) Varieties Of Brassic Napus

Rapeseed is an important oil crops in China with an annual acreage of about 6.0 106hm2and 3.0 109~3.5 109Kg oil. It is predicted that its acreage will be 7.0 106 hm2 in the near future. At present, double low hybrid breeding is the major aspect of rapeseed breeding. The genetic diversity of germplasms has a great effect on the development of rapeseed hybrids with high quality and high yield. Molecular markers widely used in breeding could help breeders to obtain the information on the genetic variation of varieties, and to produce best hybrid with elite parents. It is becoming a new research hot-spot to predict heterosis and produce best hybrid according to classification of heterosis population and genetic distance among germplasms.In this study, RAPD technique was employed to evaluate genetic diversity of some Chinese double high and double low varieties and some European double low varieties. Cluster analysis was done using RAPD markers, from which some advice was given on selection of parents for producing hybrids.The genetic diversity of 135 Brassic napus varieties was revealed by RAPD markers. A total of 279 DNA bands were produced from 37 arbitrary primers (10-base) and 225 of them were polymorphic. The average proportion of their polymorphic loci was 81%. A dendrogram has been constructed through UPGMA program. All of the varieties were divided into 5 groups. 8363 and HuayouNO.8 were divided into 2 groups, and the others were divided into the other 3 groups, e.g. Asian rapeseed group, Europed rapeseed group, and the mixed group of Asian and European varieties. The double low Chinese varietieswere distributed in the 3 groups. So the double low varieties have a wide genetic diversity. This provide a good genetic base for quality breeding and hybrid breeding in the future.At last, those such as the factors that influence on RAPD reaction, how to count the DNA bands, the selection of different clustering methods, the prediction of heterosis by several methods, the influence of the number of polymorphic bands on estimating the genetic diversity were discussed.