Study On The Genetic Basis Of Grain Quality Traits And Map-based Cloning Of GS3 For Grain Length In Rice

Grain quality is an important objective of rice breeding that is mainly defined by milling quality, appearance quality, cooking and eating quality and nutritional quality, among which the appearance quality and cooking and eating quality are most considered by consumers. But the complicated genetic basis of grain quality makes it difficult for breeders to improve grain quality efficiently using conventional genetic methods. In the study, linkage maps were constructed for mapping QTLs on appearance quality and cooking and eating quality in Zhenshan 97/H94 and II-32/H94 DH populations. In order to characterized the genetic components, including main-effect QTLs, epistatic QTLs and QTL-by-environment interactions, that are involved in the control of grain quality, the population of Zhenshan 97/H94 was used, and data were collected from a field experiment conducted in two different environments. Map-based cloning of a major QTL (GS3) for grain length and weight was also conducted. The major results were as follows:1. The genetic linkage map of Zhenshan 97B/H94 was constructed based on 219 loci, which covered a total of 1646.2 cM with an average interval of 7.5 cM between adjacent loci; the genetic linkage map of II-32B/H94 was constructed based on 187 loci, which covered a total of 1230.9 cM with an average marker interval of 6.6 cM. There were 174 common markers between two populations with marker orders on chromosomes according well with that in previous reports.2. Zhenshan 97B and II-32B exhibited similar grain quality except grain width, percentage of chalky endosperm and gelatinization temperature; whereas, they showed distinctly different grain quality with H94, in which H94 was larger in traits of grain length, grain shape, grain thickness, grain volume, grain weight and gel consistency, and smaller in grain width, percentage of chalky grains, area of chalky endosperm, degree of endosperm chalkiness, amylose content and gelatinization temperature. The DH population showed bimodal segregations for amylose content, gel consistency and gelatinization temperature, indicating the involvement of a major gene for each trait; whereas, normal distributions for the rest, indicating quantitative-inherited.3. With the data of grain quality collected from Wuhan and Hainan in 2002, 41 of 97...