Analysis And Mapping Of An Abnormal Glume Mutant Gda In Rice(Oryza Sativa L.)

Rice is one of the most important food crops in the world. It is essential to further increase the rice yield for solving the world food supplies problem. The process of flowering controls the reproductive phase of rice and is correlated with the yield and quality directly. Consequently, focusing on the development of flower will greatly contribute to rice breeding. The gda mutant was derived from Nipponbare T-DNA insertional mutant library, as material to isolate the gene through map-based cloning and made predicts for its function. The important results are as follows:1. The phenotype comparisons between glume development abnormal mutant (gda) and wild-type (wt) showed that the mutant exhibited an opening-glume,and a decrease in height that gda was89.2cm contrasted to wt’s95.3cm; Thousand grain weight in gda(65.4g) was lighter than wt(118.3g);Seed viability changed greatly, we carried out a germination experiment,the result has showed that the germination ratio in gda was only64%,lower than wt’s94%.Cytological observation indicated that the paleas elongated outside the lemma. The narrow glumes cannot enclose completely. Moreover,the lemma cell size in mutant was shortened about30μm;Owing to the anthers in mutant turned to curved,the fertility decreased so much.2. The gda mutant, as maternal parent, was crossed to Nipponbare,Nanjingl1,N22, Pushr,Dular, and made to obtain F1and F2populations. The observation of the progenies showed that all the F1plants were normal grain shape, but the grain shape in the all F2populations was segregate into glume development abnormal phenotype.4120plants with normal glume shape and1335plants with glume development abnormal shape were found in the F2population, and the segregation was fitted for the ratio of3:1(x20.05,1=3.84).This result suggests that the phenotype of glume development abnormal in the gda mutant is controlled by a single recessive nuclear locus. To map the gda locus, first we took genome scanning,found the linkage marker in the terminal on Chromosome2,then generated F2mapping population about540plants derived from a cross of the gda mutant and the cultivar Pushr and Dular.We mapped the gda to an interval between SSR markers RM3774and RM208on Chromosome2,the heredity interval is1.4cM and2.6cM,correspondingly,the physical interval is697.2kb.Comparion of chromosomal locations and glume development abnormal phenotypes indicate that this gene is different from the previously identified genes related to glume development alteration. To narrow down the search for a candidate gene affected in gda, A large F2mapping population consisting of more than5,000plants,of which1115segregants showing the gda mutant phenotype were used for fine-mapping, between markers RM3774and RM208, we further developed eleven InDel markers,the gda locus was finally located in a119.5-kb DNA region between InDel marker M1and M11. At that region, no glume development abnormal gene has been reported.