Mapping Of QTLs Underlying Traits Related To Quality Using A Recombinant Inbred Line Population In Rice

Rice is a main product of crops in our country and many other countries in Asia, and the grain quality improvement has become one of the most objectives in rice breeding program. Rice grain quality was mainly defined by milling quality, appearance quality, cooking and eating quality and nutritional quality. We always concern that molecular amelioration is the most effective way or even the only feasible method for grain quality improvement according to which these kinds of traits are dominated by series of genes and are characteristics of vulnerable to the effects of environmental conditions.And the premise factor of this improving strategy is to locate related QTLs accurately. In present study, the QTL of grain quality traits was detected by using RILs.The major results were as follows:1.A linkage map consisting of 144 SSR (simple sequence repeat) makers was constructed based on a recombinant inbred line (RIL) population from the cross between chuanxiang29B and Zhongguoxiangdao.2.The result of t-test showed that the grain length, grain width, length width rate, chalkiness rate, gelatinization temperature and amylose content of parents were significant difference (p=0.01)in the two years of 2008 and 2009.Two-way recombinant inbred lines showed transgressive segregation,similar to normal distribution. Significantly positive correlations were found between 2008 and 2009 in the same trait.3.A total of 24 QTLs were identified for grain length, grain width and length-width rate were mapped on the chromosome 1,2,3,4,6,7,9,10 and 12, each of the main-effect QTLs individually explained 3.0% to 18.2% of the phenotypic variations, and three of those QTLs (qGL3-1;qGW9;qLWR4)can be detected in both two years.4.A total of 10 QTLs were identified for chalkiness rate were mapped on the chromosome 2,4,6 and 7,each of the main-effect QTLs individually explained 4.0% to 25.4% of the phenotypic variations,and two of those QTLs (qCR6-4;qCR7-1)can be detected in both two years.The QTLs were co-localized on the chromosome 6 and 7,Wx gene on chromosome 6 was also effected on chalkiness rate.5.Refer to amylose content and alkali spread value,there are 11 QTLs were mapped on the chromosome 1,2,3 and 6,each of the main-effect QTLs individually explained 2.5% to 81.5% of the phenotypic variations,qAC6 which was identified for amylose content can be detected in both two years,and qAC6 is closed to Wx locus.Our results, combining previous reports,further confirmed that either the Waxy gene itself or a genomic region tightly linked to it play a major role in determining the amylose content.qASV6-1,qASV6-4 and qASV6-5 which were identified for alkali spread value can be detected in both two years.QTL analysis revealed two major QTLs specifying GT, which should be the same locus as the alkali degeneration gene (alk), it showed that alk play an important role on alkali spread value.