Prediction Of Heterosis Using Molecular Markers In Brassica Napus L.

Heterosis is a common phenomenon in biosphere. Application of heterosis is one of the most effective ways to enhance yield potential and to improve crop quality. The mechanism of heterosis should be elucidated in order to utilize plant hertorosis more efficiently. Researchers had quested a lot for the origin of heterosis and get a number of conclusions.Rapeseed is one of the most widely planted oil crops worldwide. The planting area and output of rapeseed in China is about one third of the world's total amounts and ranked first among all the rapeseed growing nations. Hybrid cultivars account for over 50% of China's total acreage of rapeseed. The traditional method of parent mating takes too much manpower and material resource, while it has long periods and low efficiency. The utilization of rapeseed heterosis need a simple and effective way to guide the parent mating. This need was satisfied by molecular marker, which reflects the abundant steady information at DNA level. Molecular marker techniques have been widely used in the researches on the prediction of heterosis and genentic basis in many crops, however a little has been reported on heterosis prediction though molecular markers in rapeseed.In present study about the heterosis prediction of rapeseed (Brassica napus L.), the hybrids were produced using incomplete diallel cross design. The relationships between the genetic distances of parent molecular makers, the maker values of parents and hybrids and the heterosis of hybrids were elucidated based on the analysis of DNA fingerprint data of parents and the F₁ 's trait data. The mathematic models for heterosis prediction by molecular markers were set up according to the stepwise regression analysis. The results are as follows:1. Analysis of genetic relationships among hybrid parents910 polymorphic loci were detected through the amplification of genomic DNA templates of 19 hybrid parents using 283 pairs of SSR primers, 64 pairs of AFLP primers and 81 pairs of SRAP primers. The hereditary distances of the molecular makers in 19 parents were calculated according to the 910 polymorphic loci, and cluster analysis was carried out using UPGMA method. The results of cluster analysis were almost consistent to the trait performance of the parents. In general, hereditary differences between black-seeded lines and yellow-seeded lines were greater than those within each type.