Map-based Cloning For QTL On Panicle Apical Degeneration Of Rice

Spikelet degeneration at the top of panicle leads to albinism in rice tip (commonly known as baldness) and reduction of the number of grains per panicle, affecting rice yield. This phenomenon is under the influence of environmental factors such as temperature and moisture.E10-td, the mutant of our research, serious in apical degeneration, is from a transgenic line of Kasalath (an indica variety) transformed by a BIBAC. However, this phenotype is neither linked with the inserted fragment nor shown in the Fi generation from the cross between e10-td and Hejiang19(a japonica variety). The segregation of character and the continuous distribution of phenotypic variance appear in the F2generation, implying the phenotype is a quantitative trait controlled by multiple genes.The genotypes of the F2population grown in Beijing in2012are detected via126molecular markers along the whole genome. QPAD2, a QTL with major effect, is identified within a95-kb interval in chromosome2by winQTLcart. Via the comparison and analysis of transcriptomes between wild-type Kasalath and the mutant, a differentially expressed gene, SCD(LOC_Os02g30200) encoding the Stearoyl-ACP Desaturase3which plays a role in lipid metabolism, is identified within the QTL candidate interval, and meanwhile, the fact that genes related to hydrolase activity acting on glycosyl bonds and ester bonds are significantly enriched among differentially expressed genes is also revealed.Two candidate genes within the QTL candidate interval, SCD and FBK7(LOC_Os02g30210), are validated preliminarily in genomic level, and no mutation is found. Overexpression vectors and RNAi vectors are constructed, aiming at preliminarily exploring the functions of the candidate genes by transgenic approaches.