QTLs Analysis On The Stigma Traits In Rice

The stigma is an important organ for receiving pollen in rice. The stigma traits of rice ,including the percentage of exserted stigma,the stigma length (STL), the stigma breadth (STB), the style length (SYL),are directy associated with the pollination of rice.Therefore selecting male sterile lines with a higher percent of excerted stigma and a higher rate of outcrossing will play an very important role in increasing yield of hybrid rice seed production.To exploit the genetic basis of the stigma traits,we developed an F2 popullation,derived from a cross between T821B and G46B.The major results were as follows:1.A genetic linkage map,contained 97 SSR markers, was constructed.The map covered a total of 1322.5cM with an average interval of 13.6cM.2.The percentage of total exserted stigma(PES) had a significant positive correlation with the percentage of dual exserted stigma(PDES) and the percentage of single exserted stigma(PSES).STL had a significant positive correlation with the length of style and the stigma(SSL),STB and SYL, respectively.The percentage of exserted stigma,including PES,PDES,PSES,had no significant correlation with STL STB,SSL and SYL,respectively.A significant positive correlation was found between No of primary branches per panicle (NBP) and PSES.3.Thirteen QTLs distributing on six chromosomes were detected for PES,PDES and PSES.Among these QTLs,five QTLs were found to influence PES with accumulated contribution of 90.22%. The major QTL for PES,qPES-9,with the LOD score of 23.45 and explaining 65.21% of total variance,was detected on chr 9.Four QTLs affecting PDES were found,explaining 64.23% of total variance.The contribution and the LOD score of the major QTL for PDES,qPDES-9,was 47.73% and 17.65 respectively.There were four QTLs for PSES with accumulated contribution of 44.45%,in which qPSES-9-1 and qPSES-9-2 explained 16.04% and 17.83% of the total phenotypic variance,respectively.4.Five QTLs associated with STL were detected.The phenotypic variance explained by each QTL ranged from 4.89% to 11.17%. A minor QTL for STB was found.Two QTLs for SYL were identified,explaining 14.14% and 8.40% of total variance respectively.Three QTLs for SSL were detected,with affecting 14.54%,6.26% and 6.80% of the phenotypic variance respectively.5.Two QTLs for NBP,qNBP-3 and qNBP-6, were identified on chr.3 and 6,explaining 18.78% and 13.17% of phenotypic variance respectively.