Direct Genetic Improvement Of Heading Date For Rice Photo-thermo-sensitive Genic Male Sterile Line Xl628s And Development Of Japonica Thermo-sensitive Genic Male Sterile Lines

Rice is a typical short-day plant.Under domestication and artificial selection,the sensitivity photoperiod of rice decreases gradually in some of rice varieties,and the regional adaptability is improved,which can enlarge the planting range of rice.In order to make use of the light and temperature conditions of various regions to obtain the optimal yield of rice,it is necessary to optimize the heading date of rice according to the light and temperature conditions of different ecological regions.According to the previous study on the relationship of the heading date gene in rice and adaptability of rice,we found that the combination of heading date genes affects the length of heading date.Especially when the combination comes to the strong function of Ghd7,Ghd8 and Hd1 genotypes?SSF?,the phenotype would be extremely late of heading date,or even no flowering.This combination of gene can only suit for tropical areas planting.The growth period in F₁ is decided by the genome of parents.When 628S,the photo-thermo sensitive male sterile?PTGMS?line,paired with other restorer lines,the heading date of F₁ can be great delay.The accumulation of functional genomics research results and the rapid development of gene editing technology provide many new ideas for plant breeding.Using the CRISPR/Cas9 system,which is fast,accurate and low-cost gene editing technique,can avoid the disadvantages such as time-consuming and easy to appear the Linkage drag in traditional rice breeding.The two-line heterosis played an important role in the production of indica,while the two-line method in heterosis was hardly used in the production of japonica.In this study,we use 628S as the study object to conduct the major heading gene information in 628S and some of restorer lines through gene diagnosis,haplotype analysis,and modify 628S by using CRISPR/Cas9.Then create a new japonica PTGMS lines to slow down the difficulty of breeding and speed up the process of breeding through the same gene editing technique.1.when conduct the major heading gene information in 628S and some of restorer lines,we found that the three gene combination of Ghd7Ghd8Hd1 of F₁ hybrid with628S was SSH,which resulted in late heading date and failure of flowering.The combination of SSN?Ghd7Ghd8hd1?that destroys Hd1 function can theoretically obtain the high-yield combination with suitable growth period.Therefore,we attempted to alter 628S by using CRISPR/Cas9 system to edit Hd1 precisely and efficiently and named the modified material to 628SM,and the crossing progenies with restorer lines to mF₁.The results of 628S,628SM,F₁ and mF₁ heading dates in short day and long day condition was statistically analyzed.2.using CRISPR/Cas9 technique to edit photo-thermo sensitive genes pms3,tms5and wide compatibility gene ORF4-j in japonica material that named Oryza sativa L.ssp.japonica CV.Zhonghua 11?ZH11?to create a japonica PTGMS quickly,which are the pms3+orf4-j mutant and tms5+orf4-j mutant.The T₀ mutants has been identified and received the crossing progenies between T₁ and some of indica restorer lines in Hainan.