Construction Of Genetic Linkage Maps And QTL Analysis For Quality Related Traits Of Rice(Oryza Sativa L.)

Rice is the staple food in China,which feeds up 65%of the population.In recent years,with the continuous improvement of people's living standards,the demand for superior rice grain quality is increasing.The components of rice grain quality include milling quality,appearance quality,eating/cooking quality,and nutritional quality.Among these quality properties,consumers pay more attention to the fine appearance,high eating and nutritional quality,which are major goals of rice genetics improvement.Grain qualities belong to quantitative traits,which are controlled by several genes and easily affected by environmental conditions.It is difficult for traditional breeding methods to improve quantitative traits.In order to characterize the genetic components involved in the control of grain quality,data were collected from a recombinant inbred line derived from the cross between Nanjing 46,a elite japonica variety in Jiangsu with superior grain quality,and Zhaxima,an landrace indica variety in Yunnan.The results are as followers:1.A molecular linkage map consisting of 175 SSR markers was constructed using 144 lines of the RIL population.The map spans a total of 1,434cM,with an average marker interval of 8.2cM.Marker order on the chromosomes agreed well with that of the published maps.2.In six traits investigated,only the amylase content segregated at the ratio of 1:1,indicating the involvement of a major gene,whereas normal distribution of the other traits was observed,indicating qualititative-inherited.3.A total of 16 additive QTL were identified on ten chromosomes except chromosome 1 and 4.Each QTL explained 2.66-53.27%of the phenotypic variance.The qAC-6 for amylase content had the largest effect.Compared with QTL previously reported for these traits,fourteen additive QTL were newly identified:qGL-9 and qGL-11 for grain length,qGW-6 for grain width,qLWR-6,qLWR-8a,qLWR-8b for grain length-width ratio,qGT-5,qGT-12 for grain thickness,qAC-5 for amylase content and qPC-3,qPC-7 for protein content.