| Rice is one of the most important cereal crops in the world.With the rapid growth of the population and the improvement of living standards,it is necessary to further increase yield and improve rice quality.Ratoon rice is a cultivation mode that improves yield of rice in the areas where light and temperature resources are not enough to grow the second season rice,and the quality of ratoon rice is excellent(but the milling quality is inferior),so it has made a huge contribution to meeting people's current demand for high yield and quality.However,the genetic basis for the yield and quality(especially the milling quality)of ratoon rice is not yet clear,and there is a serious lack of breeder rice varieties.Therefore,there is an urgent need to dissect the genetic basis of yield and milling quality of ratoon rice,to map QTLs that affect yield and milling quality of ratoon rice,to mine QTLs that are stably expressed in different genetic backgrounds,and to apply them to molecular breeding to increase yield and improve quality of ratoon rice.In the present study,a set of introgression line population derived from Minghui 63(Three line indica rice restorer line)as recipient parent and 02428(japonica rice wide compatibility variety)as donor parent was successfully developed.The 18 yield and milling quality related traits of ratoon rice were measured in Jingzhou.Using a high-density bin map,identify the main-effect QTL and epistatic QTL that affect the yield and milling quality of ratoon rice,and using introgression lines derived from 02428 as recipient parent and Minghui 63 as donor parent to evaluate impact of these QTLs caused by genetic background and verify important QTL by using introgression lines.The main results are as follows:(1)Among the yield related traits of ratoon rice,the maximum tiller number,panicle number and grain yield per plant of Minghui 63 were significantly higher than 02428 in normal season and ratoon season.And the tiller number ratio,panicle number ratio of Minghui 63 were also significantly higher than 02428.Among the milling quality related traits of ratoon rice,the milled rice rate in normal season of Minghui 63 was significantly higher than 02428,while the head milled rice rate was significantly lower than 02428.The brown rice rate in ratoon season of Minghui 63 was significantly higher than 02428,while the milled rice rate and head milled rice rate were significantly lower than 02428.In the end,the milled rice rate ratio of Minghui 63 was significantly lower than 02428,while the other two traits(brown rice rate ratio and head milled rice rate ratio)were not significantly different.The results showed that yield of ratoon rice of Minghui 63 was significantly better than 02428,while milling quality of ratooning rice was significantly worse than 02428.The 18 traits of the yield and milling quality of ratoon rice of introgression lines showed continuous distributions and transgressive segregation,indicating that all these traits are quantitative traits and controlled by multiple genes.(2)There was a significant positive correlation between different yield related traits in the same season.The tiller number ratio,panicle number ratio and grain yield ratio were significantly positively correlated with three traits in ratoon season,while they were negatively related with the three traits in normal season.There was a positive correlation between different milling quality related traits in the same season.Brown rice rate ratio,milled rice rate ratio,and head milled rice rate ratio were significantly positively correlated with three traits in ratoon season,while they were negatively related with the three traits in normal season.(3)Combining the phenotypic values of yield and milling quality related traits of ratoon rice and high-density bin map in the introgression line population,15 and 17 main-effect QTLs affecting the yield and milling quality of ratoon rice were identified,of which 7.15-11.41 Mb on chromosome 4,12.14-14.65 Mb on chromosome 5,4.64-5.76 Mb on chromosome 8,10.64-15.52 Mb on chromosome 11,3.88-5.51 Mb and 24.00-25.37 Mb on chromosome 12 showed pleiotropic effect on multiple traits.In addition,192 and 160 epistatic QTLs affecting the yield and milling quality of ratoon rice were identified,of which 42 epistatic QTLs showed pleiotropic effects on multiple traits.(4)Using 15 introgression lines derived from 02428 as recipient parent and Minghui 63 as donor parent to evaluate the effect of genetic background on the main-effect QTL,the results showed that 14 QTLs(q NTN5,q NPN5,q TNR5,q PNR5,q RBRR12.1,q RBRR12.2,q RMRR12.1,q RMRR12.2,q RHMRR12,q BRRR12.1,q BRRR12.2,q MRRR12.1,q MRRR12.2 and q HMRRR12)were also identified at 02428 background.(5)A pleiotropic region of 14.12-14.65 Mb on chromosome 5 stably expressing at both backgrounds was validated for maximum tiller number and panicle number in normal season and tiller number ratio,panicle number ratio and grain yield ratio using an Minghui 63 background introgression line. |
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