Development Of Single Segment Substitution Lines Between Two Sequenced Rice And Mapping Important QTLs

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. Chromosome segment substitution lines are called substitution lines or introgression lines generally. 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, the two sequenced rice varieties indica rice cultivar 93-11 and japonica rice cultivar Nipponbare were respectively used as recurrent and donor parent to produce a single segment substitution lines population, by using microsatellite market-assisted selection (MAS). And on this basis, mapping and analyzed important traits between Nipponbare and 93-11 subspecies. The main results were as follows:1.447 microsatellite markers which uniform distribution on rice 12 chromosomes were used to indentify polymorphism between recipient parent 93-11 and donor parent Nipponbare.227 molecular markers,50.78% of totals, showed polymorphism between the two parents. Finally, a molecular map that based on Nipponbare was developed and 221 markers more or less distributed in 12 chromosomes on this map. The average distance between two adjacent markers on this map was 1.64Mb.2.58 different SSSLs with the 93-11 genetic background have been developed in BC3F2,BC4F2 and BC5F2 generations. Substituted segments of these SSSLs uneven distribute on 12 chromosomes of rice. The largest proportion of single segments 10 of 58 in Chr5, and the smallest proportion of single segments hold 2 of 58 in Chr3, Chr4, Chr7, ChrlO and Chr12. The length of the 58 SSSLs is from 0.58Mb to 11.67Mb and the average length was 4.83Mb.139.53Mb of rice genome is covered by 58 SSSLs and the coverage is 37.48%.3. Student t-test (p<0.001) showed 33 QTLs have significant difference between 26 of 58 SSSLs and 93-11. There are 27 different QTLs in 33 QTLs. Among these 6,3,11, 4,3 QTLs are respectively involved in grain weight (Gw), heading date (Hd), plant height (Ph), spikelet setting density (Ssd) and spike length.4. Using overlapping substitution mapping of 5 SSSLs, we mapped compact plant architecture with extremely erect tillers QTL. The QTL which controlled the tiller angle was mapped to a 2.97Mb region of the long arm in Chr9, the upstream and downstream nearest markers are RM278 and CS0920. Further results show TAC1 and TAC2 genes which also controlled tiller angle have been cloning and mapped in this area, respectively.