Rapid Generation Technology Research And Homozygosity Analysis In Flower Chinese Cabbage

Flowering Chinese cabbage?Brassica rapa L.ssp.chinensis var.utilis Tsen et Lee?is one of the favourite vegetables in south China.To creat a stable inheritance populations,Flowering Chinese cabbage would take more than six generation of selfing to satisfy those heterozygote.The main factor restricting the progress in its breeding and genetic studies is the time required in generating desired pure line populations.In order to shorten the length of generation cycles,the rapid generation technology is needed.Using several varieties and hybrid materials of flowering Chinese cabbage,the rapid generation technology has been studied and SSR molecular marker technology has been used to identify the homozygous DNA loci of the selfing strains derived from the repid generation technology.Flower induction of in vitro culture has also been discussed in this research.The main results are as follows:1.Artificial environment using soil method could shorten the cycle of one generation and promote blossom efficiently under the condition: temperature of25-30 ? with the light intensity of 350 ?mol·m^-2·s^-1.It took average 30-48 d to flower among all these samples.2.Artificial environment using soil method plus embryo culture could culture the12 d young embryo on the medium?MS + 10% coconut juice +1% sucrose?for 7 d to obtain young seedling.These seedlings would be transplanted into soil to start the next generation.In this method,one cycle would be completed in 52-64 d among all samples,which saved 30 d approximately compare with natural maturity.The research could produce 5-6 generations per year using this protocol.3.In vitro cuture could not induce blossom by adding GA or changing sucrose concentration in MS mediu.The research indicates the complexity of in vitro inducing blossom and seed setting of flowering Chinese cabbage.4.Seven different selfing strains were examined to identify the homozygous DNA locus of the hybrid seeds?Sijiu-19×3T-6?of F5 plant generations.The ratio of homozygous locus in five lines were 83.3%.The result indicates that rapid generation technology can truly speed up the growth and have an advantage on ensuring the accuracy of self-pollination.We need to continue to conduct the fast generation technology to increase homozygsity.The molecular markers of SSR combining with rapid generation technology can be used to screen accurately target plants and shorten time of breeding.