Qtl Analysis Of Main Agronomic Traits And Heterosis Study Based On Chromosome Single Segment Substitution Lines In Rice (Oryza Sativa L.)

Rice is one of the most important crops which is also one of the model organisms for plant molecular biology. So it is useful for plant breeding to understand the genes’function in rice. Most traits of crop are quantitative, which are controlled by polygenes. Fine mapping of quantitative trait loci (QTL) is very important for crop genetic and breeding improvement. Single segment substitution lines (SSSLs) containing only one chromosome segment of donor in the recipient genetic background are useful for the analysis of genes or QTLs. In this research, as the indica rice cultivar93-11receptor, Japonica Rice Varieties Nipponbare and three line hybrid rice restorer line Shuhui527backbone for the donor, by using microsatellite market-assisted selection (MAS), a set of single segment substitution lines (SSSLs) population has been established..And on this basis, the research have been carried out abou analysis of important traits and heterosis. The main results are as follows:1.447microsatellite markers which uniform distribution on rice12chromosomes were used to indentify polymorphism ammong recipient parent93-11,donor parent Nipponbare and Shuhui527.247molecular markers were showed polymorphism among these parents,221molecular markers,50.78%of totals, showed polymorphism between93-11and Nipponbare,55molecular markers,12.30%of totals, showed polymorphism between93-11and Shuhui527. Finally, a molecular map that based on93-11was developed and247markers more or less distributed in12chromosomes on this map. The average distance between two adjacent markers on this map was1.85Mb.2.80different SSSLs with the93-11genetic background have been developed in BC3F2^BC4F2and BC5F2generations. Substituted segments of these SSSLs uneven distribute on12chromosomes of rice. The largest proportion of single segments24of80in Chrl,Chr2, Chr4.The smallest proportion of single segments hold9of80in Chr9. The length of the80SSSLs is from0.52Mb to26.13Mb and the average length was6.83Mb.194.89Mb of rice genome is covered by80SSSLs and the coverage is31.03%. 3. Student t-test (p≤0.001) showed55QTLs have significant difference between55of80SSSLs. There are46different QTLs in55QTLs. Among these6,10,13,10,3QTLs are respectively involved in grain weight (Gw), heading date (Hd), plant height (Ph), spikelet setting density (Ssd) and spike length. The additive effect of different Trait’s QTL,the additive effect of,the Ph QTL,was the most, it was26.93; grain density additive effect of minimum-19.53. Except of Ph QTL most of the value of additive effect were negative effect. qHd-6-1, qEpn-8--5, qHd-9--5, qSsd-11-2--5, qSsd-12--5have not been reported they were the new QTL located in This study.4.Using overlapping substitution mapping of5SSSLs, we mapped compact plant architecture with extremely erect tillers QTL. The QTL which controlled the tiller angle was mapped to a2.97Mb region of the long arm in Chr9, the upstream and downstream nearest markers are RM278and CS0920.5.Using the developed SSSLs, a QTL of the heading date was located on a181.5Kb region of the long arm in Chr6, the upstream and downstream nearest markers are RM20176and RM20196. The F2segregating population from backcrosses to recipient parent93-11. In the segregating population, the segregation ratio of early, middle and late heading plants matched1:2:1, indicating this allele is incomplete dominance genes.It’s a new gene about HD.6. We screened the SSSLs(Shuhui527as the donor) and got12SSSLs which background are similar.Using the12SSSLs as male,H2S(a nucleic male sterility rice line in Sichuan),Y58s and Guanzhan63s(two elite amphibious sterile lines used widely in China)as female,we studied the yield and its relatived agronomic traits.Also, we analysed the heterosis and combining ability. We got those results:Yield and its related agronomic traits’ heterosis is significantly variation among the chromosome segments.The SSSLs which contain the heterosis of grain weight per plant(GWPP) are on Chr.5and Chr.6,the segments are RM528-RM103, RM592-RM39and RM274-RM26.The HOCH of the combinations Guangzhan63S/V261and Y58S/V296are28%and24.4%respectily,all get significantly variation. We discovered a hybrid weakness segments on Chr.5defined by marker RM592and RM39.The line is V266and its relative HOCH of GWPP is -7.10%.We alse discovered that the segment RM203-RM55-RM8209-RM448-RM227on Chr.3possesses a high general combining ability(GCA) of GWPP. Oppositely,the GCA of the segment RM25～RM310～RM342A on Chr.8is minimum.