Generating Salt Tolerance And Bentazon Sensitivity Germplasms By Editing OsRR22 And Bel Via CRISPR/Cas9 Technology

Salt stress is one of the most important abiotic stresses affecting the growth and yield of rice.Exploring genes and creating rice varieties related to salt tolerance is therefore of paramount importance for food security.Additionally,the development of hybrid seed production technology has greatly increased rice yield.Since the interplanting of sterile lines and restorer lines of hybrid rice easily affects the purity and mechanization level of hybrid rice seed production,breeding of herbicide-sensitive restorer lines is beneficial to reducing the artificial cost of hybrid seed production,raise the mechanization level of hybrid rice production.Based on previous studies,this experiment analyzed the improvement effect of target characters of pure lines with mutation of salt-tolerant negative regulatory gene OsRR22 and bentazon sensitive lethal gene Bel edited by CRISPR/Cas9 technology,so as to provide excellent germplasm resources for mechanized seed production of salt tolerant hybrid rice.The main results are as follows:1.OsRR22 and Bel gene-edited pure line materials with genetic background of Indica Rice Yuehesimiao were selected,which showed base insertion and deletion.2.Homozygous mutants KO-1～KO-3 were treated with 0.8%NaCl stress.After treatment for 20 days and recovery for 10 days,the average inhibition rates of seedling length,root length,fresh weight and dry weight of the three mutant lines of KO-1～KO-3 were 6.1%,6.52%and 6.72%respectively,and that of wild-type plants was 18.26%.The survival rates of KO-1～KO-3 were 83.33%,78.26%and 79.17%,which were significantly higher than those of wild-type plants.It was found that the effective panicle number and 1000-grain weight of KO-1 decreased significantly,while the effective panicle number of KO-2 decreased significantly.There was no significant difference between KO-3 and wild type.3.After four concentration gradients of 36 mg/L,72 mg/L,720 mg/L and 1440 mg/L bentazon solution,the leaves of Bel homozygous mutants showed different degrees of green withering and yellowing,while spraing water as the control group.The plant height,fresh weight and dry weight of mutants treated with 720 mg/L and 1440 mg/L concentrations decreased significantly,notably the mortality of mutants reached 100%at 1440 mg/L for 10 days and 100%at 720 mg/L for 20 days.