Gene Effect Analysis And Evaluation Of Application Potential Of 6442S-7's Dominant Earliness Gene Induced Into Rice CMS Line II-32A

Heading date is one of the important agronomic traits of rice,and it determines rice adaptation of planting region and season.Utilization of dominant earliness genes can not only enlarge the genetic difference of two parents,but also transform many excellent late-maturing hybrid combinations into early-maturing and high-yielding combinations rapidly.It is generally suggested that earliness is controlled by major recessive genes and/or minor polygenes in rice.Nevertheless,a few of dominant earliness genes have been reported.Tsai firstly identified dominant earliness gene Ef-1 in japonica varieties.Ef-1 gene was located at chromosome 10 of rice and could generally advance rice to head about 10 days earlier.Sato et al.identified dominant earliness gene Ef-x located at chromosome 2 in japonica varieties.The earliness effect of Ef-x gene itself was smaller and sensitive to temperature.But the combined effect of Ef-x and Ef-1 increased extremely and was insensitive to temperature.Deng etal.firstly found out the dominant earliness gene Ef-cd in lndica.Ef-cd gene was mapped on the short arm of rice chromosome 3,6.7cM from the microsatellite marker RM231.Through continuous backcross,self-pollination and molecular marker assisted selection, individual Ef-cd gene was isolated and its nearly isogenic lines(NILs) were constructed.In this study,analyzed earliness effect of earliness gene and its effect on the other main agronomic traits,evaluate the application potential in breeding for early-maturity hybrid rice.The results were as follow:1.Genetic analysis of the early-heading isogenic lines.From segregation of heading date in the F₂ population of the nearly isogenic lines E32-9A crossed with the 9308R and segregation of heading date in the B₁F₁ population of the nearly isogenic lines crossed with the recurrent parentsâ…¡-32B,the nearly isogenic lines were testified.The result showed that the segregation ratio of early to late heading plants in the F₂ populations fitted the ratio of 3:1 and in the BC₁ populations fitted the ratio of 1:1.The results showed that:the salience single gene controled the earliness of the nearly isogenic lines2.Analysis of earliness effect of earliness genes.The nearly isogenic line E32-9A crossed with the parents M63,881R,885R etal.andâ…¡-32A crossed with the same parents,were planted in Wenjiang,respectively.The results suggested that heading dates of the early F₁ were divided into four types.The first type showed 14～24d earlier than that of the late F₁.The heading dates of the nearly isogenic line E32-9A and E32-9B were 9～15d earlier thanâ…¡-32A andâ…¡-32B.earliness genes could ahead the heading date of hybrid rice evidently,but its application had localization,due to the restraination among late genes or sensitization genes.3.Analysis effect of earliness genes about main agronomic character and output. This study sowed early or late hybrid rice in two times,were investigated,which included heading date,plant height,panicles per plant,spike length,flag leaf length, flag leaf width,the number of fertile seed,setting rate and 1000-grain weight etal.The results were that:The differences of heading date,plant height,flag leaf length among early or late hybrid rice and early or late parents were significant at 0.01 level,the number of fertile seed and setting rate among early or late hybrid rice and early or late parents were significant at 0.05 level,flag leaf width and 1000-grain weight was no significant difference among early or late hybrid rice and early or late parents.4.Analysis effect of earliness genes about rice quality.The experiment analysed the Physical/chemical quality indicators and Rice RVA profile characteristics in two date.the Physical/chemical quality indicators included ASV etal showed significant at 0.01 level among early or late hybrid rice and early or late parents.The experiment analysed effect of earliness genes about Rice RVA profile characteristics minutely,AC,GC and RVA profile characteristics had no significant difference among early or late hybrid rice and early or late parents.The results were:earliness genes had small infection to rice quality.