The Fine Mapping Of Quantitative Trait Loci Controlling Rice Regeneration Frequency And Predicting Analysis Of Candidate Genes

Establishment of rice tissue culture system is the foundation of research on gene functions and rice genetic improvement based on biotechnology. To a large extent, genetic transformation efficiency of a rice variety depends not only on the environment conditions but also on its genotype which is the biggest barrel. The japonica rice is easily amenable to a highly efficient tissue-culture system, which has greatly accelerated the development of the transgenic lines. In contrast, indica variety is relatively more recalcitrant to tissue culture, and consequently its genetic transformation has been very difficult. Studying on the difference of genetic background between japonica and indica can help us to identify the genes which will improve the tissue culture ability in rice.With the assistant of molecular marker we can select genotypes of the target traits, which are known as marker-assisted selection (MAS). This method enable us to locate QTLs (Quantitative Trait Locus) related to target traits when we use appropriate genetic population. Genes related to the traits can be identified effectively in the further study of these QTLs. So the genes associated with the culturability could be identified through marker assisted selection, and the trait for higher culture ability can be transferred from one variety to another.Some quantitative trait loci(QTLs) related to frequency of plant regeneration were mapped by using a chromosomal segment substitution lines(CSSL) population derived from a cross between an indica rice variety "Zhenshan 97B" as recurrent parent and japonica rice variety "Nipponbare" as donor.According to the results made by Zhao (Zhao et al,2009), two CSSL lines HJ-37, and HJ-119 were selected and backcrossed with Zhenshan 97B in Hainan province.4 SSR markers showed polymorphism between the parent lines. As homozygous seeds are needed to test the phenotype, the same markers were used to screen homozygous plant in F3 population. Ultimately,10 homozygous recombinant plants were obtained in HJ-37 F3 population,25 homozygous recombinant plants were obtained in HJ-119 F3 population. 16 SSR markers were selected for the fine mapping of the two CSSLs, among which 10 SSR markers were used for the fine mapping of HJ-37 F2 population, and 6 for HJ-119.After the test of plant regeneration frequency and the mapping of recombinant sites in HJ-37, the QTL was finally mapped to 486kb.76 genes were searched by bioinformatics skills in this 486kb region.3 candidate genes were defined after they having been analyzed.Zhao Lina has already defined 2 candidate genes in the plant regeneration frequency related QTL of HJ-119. This research has constructed express vector for one of these two genes, which is preparing for the functional characterization of this gene.