Study On Heredity And Molecular Mapping Of Erect Panicle Trait In Japonica Rice (Oryza Sativa L.)

In rice, japonica cultivars with panicle erectness (PE) traits have higher yield thanones with curved panicles, so that, in recent two decades, a series cultivars with PE traithave been developed through various methods. PE cultivars are released from Zhejiangto Jilin Province with their cultivating area percentage more than 40%, and there is astrong potential in these cultivars' number and cultivating areas as well. Obviously,cultivars with PE traits have seemed to be a vital direction in high-yield varietydevelopment and play an important role in rice production of our country.Although the pioneer study of PE was in China with prominent results, mostresearches were stagnated in simple traits survey, relativity analysis and deducing bystatistic methods, which can not exhume the potential of panicle erectness ricecompletely. Nowadays, with the rapid development of molecular techniques, it is theinevitable trend for mapping PE genes by molecular mapping. Till now, these has beenonly one relative publication in this field, so it is necessary to do some research, whichis meaningful for boosting panicle erect research and enlarging the heredity basis ofpanicle erectness variety.In this study, a double haploid (DH) population derived from a cross between a PEcultivar (Wuyunjing 8) and a drooping panicle cultivar(Nongken 57) was applied, andCIM method was employed to detect QTLs of PE traits. Meanwhile, we analyzed themechanism of PE formation by this DH population and 69 japonica including cultivars with PE traits, hemi-PE traits and drooping panicle erectness traits.The main results are as follows:1. As to DH population, frequency distribution of panicle curvature acted asdouble peaks in the region of lines with PE and curved panicle, which indicated that theheredity of panicle curvature was controlled by a major gene. Through analysis ofpanicle curvature data of 2 years, the heritability of panicle curvature was calculated as85.38%, which suggested that the heredity of panicle curvature was stable and itsexpression was affected slightly by environment.2. Regression analysis of agricultural traits of panicle showed that there wassignificant contribution of panicle length, plant height and seed number of primarybranch to panicle curvature, of which, the regression coefficients of panicle length inDH population and 69 cultivars were 4.218 and 7.082, respectively. It demonstrated thatgenes controlling panicle curvature also affected plant height and panicle length,simultanously.3. We constructed linkage map of chromosome 9 via Mapmaker3.0, and 2 QTLs ofpanicle curvature were detected by WinQTLcartographer 2.5 with their accountablephenotype variation as 41.72% and 25.97%. Besides, 2 QTLs related to plant height andsome QTLs controlling panicle length were also detected.