Function Analysis Of Maize Zm MYB59 Gene And Its Homologous Gene OsMYBAS1 In Rice

The germination of rice seeds is directly related to whether the harvest of rice production.Therefore,it is of great significance to study the germination characteristics of rice seeds to promote the further development of direct-seeded rice industry.Our previous study found that Zm MYB59,a transcription factor of maize,played a negative regulatory role in transgenic tobacco and decreased the germination rate of tobacco seeds.Based on the previous research,we first studied the germination characteristics of rice seeds of T2 generation overexpressing Zm MYB59 gene and the changes of physiological and biochemical indexes under different treatment conditions.At the same time,Os MYBAS1 gene was cloned in rice.The Os MYBAS1 gene was mutated by using the CRISPR/Cas9 gene editing technology.The germination traits and physiological and biochemical indexes of T2 generation mutants were analyzed.1.Functional analysis of Zm MYB59 gene in riceThe germination rate,germination index,vigor index of T2 generation rice overexpressing Zm MYB59 gene were lower than those of wild type under 0 cm and 4 cm sowing depth.Under 4 cm sowing depth and 4 cm sowing depth with GA3 treatment,the seedling height,root length,mesocotyl length and the mesocotyl cell length and number of rice seedlings grown for 14 days were significantly lower than those of wild type.Under 4 cm sowing depth,the content of Pro,the activity of CAT,SOD and APX in overexpression rice seedlings grown for 14 d were significantly lower than those in wild type and MDA content was higher than wild type;under 4 cm sowing depth with GA3 treatment,the content of Pro and SOD in transgenic rice seedlings grown for 14 d was significantly lower than that in wild type and MDA content was significantly higher than that in wild type.In conclusion,overexpression of Zm MYB59 gene may play a negative regulatory role in the germination of rice seeds and is related to the GA signal transduction pathway.2.Cloning of Os MYBAS1 gene and bioinformatics analysisThe Os MYBAS1 gene was cloned from nipponbare and contained 714 bp coding region,encoding 237 amino acids.Os MYBAS1 belongs to R2R3-MYB transcription factor and is predicted to be a hydrophilic,labile protein localized on the nucleus.Homology analysis and phylogenetic tree analysis showed that the Os MYBAS1 protein and its homologous proteins in different species are highly conserved.The similarity of Os MYBAS1 protein to Zm MYB59 protein is 87%.and there may be some differentiation between monocotyledonous plants.It is predicted that the cis-acting element of this gene promoter has many interacting elements related to abiotic stress,hormonal response(GA etc.)and plant cell morphology.3.Functional analysis of Os MYBAS1 in riceThe p CAMB1A1300::MYBAS1sg RNA::Cas9 plant expression vector was constructed and 21 Os MYBAS1 knockout rice and 3 homozygous mutant were obtained.The germination rate of Os MYBAS1 knockout T2 generation rice seeds under 0 and 4 cm sowing depth and 4 cm sowing depth with GA3 treatment were lower than wild type rice.The seedling height of mutant rice plants grown at 0 cm sowing depth for 14 days was significantly lower than that of wild type;the seedling height,root length,mesocotyl length and coleoptile length of mutant rice plants grown at 4 cm sowing depth for 14 days were all significantly lower than those of wild type;the seedling height,root length,mesocotyl length,the length and number of mesocotyl cells of mutant rice plants grown at 4 cm sowing depth with GA3 treatment for 14 days were lower than those of wild type rice.After treated with 1.5% Na Cl/25% PEG for 48 h,the content of Pro and the activity of CAT in mutant rice seedlings grown at 0 cm sowing depth for 14 d were significantly higher than those of wild type.Therefore,it is speculated that Os MYBAS1 may play a positive regulatory role in the germination of rice seeds and may be related to the GA signal transduction pathway.Also,it is speculated that it is involved in the salt stress and drought stress response of rice seedlings.