Genetic Dissection Of Appearance And Cooking Quality Of Ratooning Rice By Two Sets Of Reciprocal Introgression Lines

Rice is one of the three major food crops in the world,and more than 60% of the world population takes it as their staple food.With the improvement of people’s living standard,consumers pay more attention to the rice quality,and its quality can directly affect the rice commercial value,agricultural production and planting technology promotion.Compared with the first-season rice,ratoon rice has the advantages of superior rice quality,short growth period,low production cost,and increased yield and income.Although there are many studies on the cultivation techniques of ratooning rice,few studies has been reportedon the genetic basis of ratoon rice quality.Therefore,it is urgent to dissect the genetic basis of the appearance and cooking taste quality of ratoon rice,map QTLs for appearance and cooking taste quality of ratoon rice,and idendity QTLs stably expressed in different genetic backgrounds.In our previous studies,two sets of reciprocal introgression lines were developed from three-line restorer line Minghui 63 and wide-compatible japonica rice variety02428.The genetic analysis of this set of introgression lines has been completed.In the present study,a total of twenty-seventraits of appearance and cooking taste quality of ratoon rice were investigated in Jingzhou.Combined with the high-density genotype,the major QTL and epistatic QTL for appearance and cooking taste quality of ratoon rice were located,and the major QTL with stable expression was found in both backgrounds.The main results are as follows:(1)For appearance quality in both first and ratoon season,the grain length and length to width ratio of Minghui 63 were significantly higher than that of 02428,while the grain width,chalkiness rate and chalkiness degree of Minghui 63 were significantly lower than that of 02428.Finally,the grain length ratio of Minghui 63 was significantly lower than that of 02428.Among the cooking taste quality traits of ratooning rice,The alkali digestion value of Minghui63 in first season and the amylose content in ratoon season were significantly higher than that of 02428,the gel consistency of Minghui63 in both first season and ratoon season were significantly higher than that of 02428,and the alkali digestion value ratio of Minghui63 was significantly higher than that of 02428,while the gel consistency ratio and protein content ratio of Minghui63 were significantly lower than that 02428.Twenty-seven traits of appearance,cooking taste quality of reciprocal introgression lines showed continuous and transgressive segregating,which indicated that these traits were typical quantitative traits and were controlled by multiple genes.(2)For appearance quality of ratooning rice,under in both genetic backgrounds,the grain length in first season and the ratoon season was negatively correlated with the grain width.The grain width was negatively correlated with the aspect ratio.Grain length was negatively correlated with chalky grain rate and chalkiness.Grain width was positively correlated with chalkiness rate and chalkiness degree.For cooking taste quality of ratooning rice,in both backgrounds,the amylose content was negatively correlated with the gel consistency.The alkali loss value was negatively correlated with the gel consistency.The content of proteinwas positively correlated with the alkali digestion value.There was a significant negative correlation between protein content and amylose content in both seasons.(3): Combined with the phenotypic traits and high-density genotypes,a total of 45 and 23 major QTLs affecting appearance quality of ratooning rice were mapped in Minghui 63 and 02428 backgrounds,respectively.Among them,the regions of16.28-17.33 Mb on chromosome 3 and 3.35-4.28 Mb on chromosome 5 showed pleiotropy for many traits.In addition,14 and 6 major QTL affecting the cooking taste quality of ratooning rice were expressed in Minghui 63 and 02428 backgrounds,respectivley.Among them,20 major QTLs were detected simultaneously in two different backgrounds,indicating that these QTLs can be stably expressed in different genetic backgrounds.Besides,89 epistatic QTLs affecting appearance quality of ratooning rice and 35 epistatic QTLs affecting the cooking taste quality of ratooning rice were located.Among them,one pair occurred between two major QTLs,namely q RDEC5 on chromosome 5 and q RDEC7 on chromosome 7.