Genetic Analysis And Gene Mapping Research Of Dwarf Tillering Mutant In Indica Rice

A dwarf tillering mutant (XMD) was found in the F₁₁ population derived from Jiahezaozhan/Tefengzhan. The XMD shows significantly short plant height(PH) , much tiller number(TN), fine stems, narrow leaves and long grains, but its seeding is normal.We established two F₂ populations: GLD1/ XMD, GC13/ XMD. The phenotypes including PH,TN,PL,IL1,IL2,IL3,IL4 and IL5 was measured and analyzed. Then we concluded: Mendelian heredity with segregated ratio 3:1 happened in the F₂ populations; The XMD is controlled by a recessive gene which induces plant dwarfing through shortening of PL and all internodes. Fearfully significant negative phenotypic correlation was observed between PH and TN in the two F₂ populations. The coefficient was -0.851^**,-0.709^** respectively.We made use of SSR markers to constructed genetic linkage map by BSA (bulk sergeant analysis) method. In GLD1/XMD population, we constructed a genetic linkage map, with 8 polymorphic SSR markers between gene pools. It covered the rice genome about 22.2cM. The average interval between two markers is about 2.8cM. In GC13/XMD population, we constructed another genetic linkage map with 7 polymorphic SSR markers between gene pools. It covered the rice genome about 73.4cM. The average interval between two markers is about 10.5cM.The QTL mapping analysis of PH and TN was conducted by MCIM (mixed-model based composite interval mapping) method in the two F₂ populations. One PH QTL and one TN QTL were detected in each population. In GLD1/XMD population, qPH-1-1 was located between two SSR makers RM302 and RM128 with genetic distances of 4.0cM,0.2cM to them, additive H^2 and dominant H^2 was 74.99% and 20.70% respectively, the total H^2 was about 100%; qTN-1-1 was located between two SSR makers RM302 and RM128 with genetic distances of 3.0cM,1.2cM to them, additive H^2 and dominant H^2 was 52.31% and 24.41% respectively, the total H^2 was about 77%. In GC13/ XMD population, qPH-1-2 was located between two SSR makers RM212 and RM128 with genetic distances of 2.0cM,1.8cM to them, additive H^2 and dominant H^2 was 45.96% and 13.72% respectively, the total H^2 was about 60%; qTN-1-2 was located between two SSR makers RM128 and RM246 with genetic distances of 1.0cM,8.1cM to them, additive H^2 and dominant H^2 was 30.07% and 13.83% respectively, the total H^2 was about 45%.From the QTL mapping results we concluded: PH and TN traits of the two F₂ populations are classical quality traits; The QTLs of the two characters with great negative correlation coefficient are located in a close region; PH and TN are likely controlled by a same recessive gene on chromosome 1, named as xmd. We improved that xmd is a new dwarf gene by comparing to the studies of other people. The xmd was roughly mapped in this research, and this result was very useful for fine mapping,cloning and functional research of the xmd .