Genetic Effect Analysis Of Combining Ability Using Recombinant Inbred Lines In Rice

Rice (Oryza Sativa L) is one of the most important crops in China and in the world. Improvement of agronomic traits to enhance rice yield for a long time, but most agronomic traits are quantitative traits, controled by ploygenes and affected by environment, so it's difficult for breeders to improve quantitative traits using conventional methods. With the advent of molecular makers and QTL mapping methods, there is an opportunity to dissect the quantitative traits.In this study, two recombinant inbred lines B5/Mhui63 and Zhongguoxiangdao/ Mhui 63 were selected as plant materials, a total 17 restorer lines were selected by molecular marker-aided selection from these two RILs. of these, 8 restorer lines with planthopper resistance (Bph14/Bph15) and fertility restorer (RF3/RF4) genes from B5/Mhui 63 RILs, 9 restorer lines with fertility restorer (RF3/RF4) genes from Zhongguoxiangdao/ Mhui 63 RILs. NCII experiment derived from crossing between 17 restorer lines and 3 wild-abortive type cytoplasmic male sterile (CMS-WA) lines was conducted to analyze combining ability,relative genetic parameters and correlation of nine agronomic traits. And a RILs population consisting of 242 recombination inbred lines, derived from Minghui 63 and Zhongguoxiangdao, was used to construct a genetic map, two testcross populations were construct by crossing the RILs with two thermo-sensitive genic male sterile(TGMS) lines, M201S and 6303S, measure 9 agronomic traits values in RILs and two testcross populations. Genetic effect analysis of combining ability using recombinant inbred lines in rice, and conducted single marker analysis for 9 agronomic traits in RILs,GCA and testcross populations at P<0.05. The main results are summarized as following:1,Analysis of combining ability on 17 restorer lines with planthopper resistance (Bph14/Bph15) and fertility restorer (RF3/RF4) genes indicated that the general combining ability of nine agronomic traits except tillers per plant were significant difference ( P<0.05 and P<0.01), The special combining ability of heading date, grains per panicle and seed setting were highly significant difference ( P<0.01). These traits were controled largely by additive effect. Most traits were affected by sterile lines except plant height and seed setting which were influenced more greatly by restorer lines. The broad heritability and narrow heritability of most traits were obviously higher than 60%. Broad heritability and narrow heritability of tillers per plant and yield were obviously lower than 50%. Yield were significant correlation with tillers per plant,grains per panicle and seed setting at P<0.05 and P<0.01. Correlation coefficient were significant at P<0.05 and P<0.01 between general combining ability and phenotypic values for most traits.2,Identified quantitative trait loci (QTL) using RIL with two year (2007,2008). The number QTLs varied according to the different traits, a total of 82 QTLs were detected for 9 traits in two year, 55 QTLs were detected for 9 traits in 2007, 51 QTLs were detected for 9 traits in 2008. of these 24 QTLs were simultaneously detected in two year: 1 QTL for heading date, 4 QTLs for plant height, 4 QTLs for tillers per plant, 1 QTL for seed setting, 5 QTLs for 1000 grain weight and 9 QTLs for panicle length. All QTLs explained 1.68%～14.03% of total phenotypic variations.3,QTL detected in the RILs,testcross populations and GCA. except grains per panicle, a total of 39 QTLs were detected for other traits in M201S/RIL testcross population, each QTL explained 4.37%～16.99% of total phenotypic variations. A total of 35 QTLs were detected for 9 traits in 6303S/RIL testcross population, each QTL explained 2.23%～7.71% of total phenotypic variations, a total of 37 QTLs were detected for 9 traits in GCA, each QTL explained 6.51%～31.1% of total phenotypic variations. A total 29 common QTLs were detected in RILs,two testcross populations and GCA, of these 4 QTLs were detected in the four populations, 5 QTLs were detected in the three populations, 20 QTLs were detected in the two populations. Some QTLs appeared to be pleiotropic effects in difference populations.