tRNA硫醇化修饰介导植物盐胁迫响应的分子机制OA

[Objective]To analyze the expression levels and phenotypes of CTU2,CTU1 and URM11,the key genes in the tRNA thiolation pathway,in mediating salt stress in Arabidopsis thaliana,and explore the molecular mechanisms by which these genes mediate the plant salt stress response.[Method]Subcellular localization analysis was performed to determine the localization of AtCTU2 in cell compartments;The expression level of AtCTU2 gene after 150 mmol·L-1 NaCl treatment was ana-lyzed via quantitative real-time PCR(qRT-PCR);The atctu2 mutant was identified at the DNA level,and the expression levels of salt stress-responsive genes AtP5CS1 and AtRCI2A were detected by qRT-PCR;The yeast two-hybrid system was employed to detect the complex formation among AtCTU1,AtCTU2 and AtURM11 proteins;The expression levels of AtCTU1 and AtURM11 genes after NaCl treatment were analyzed by qRT-PCR;The atctu2,atctu1 and aturm11 mutants were cultured on media containing 100 and 150 mmol·L-1 NaCl for observing phenotypes and statistically analyzing the proportion of green cotyledons.[Result]In protoplasts derived from etiolated seedlings,the AtCTU2-GFP fusion protein was localized in both the nucleus and cytoplasm;In protoplasts derived from green seedlings,AtCTU2-GFP was exclusively localized in the cytoplasm.The expression level of AtCTU2 gene in Arabidopsis thaliana was significantly upregulated after NaCl treatment.In the atctu2 mutant,the expression levels of salt stress-responsive genes AtP5CS1 and AtRCI2A were downregulated.Inter-actions were detected between AtCTU1 and AtCTU2 proteins,and between AtCTU1 and AtURM11 proteins.Under non-NaCl stress conditions,there was no significant difference in the growth status between the wild type and atctu1,atctu2 and aturm11 mutants.After NaCl treatment,wild-type plants exhibited mild growth retardation and cotyledon yellowing,while all mutants showed a signifi-cant reduction in germination rate and obvious growth inhibition.Among them,the atctu2 mutant had the greatest sensitivity to salt stress,followed by aturm11 and atctu1 mutants,and the statistical results were consistent with the phenotypic observations.[Conclusion]CTU2,CTU1 and URM11,the key genes in the tRNA thiolation pathway,are involved in regulating salt stress tolerance in Arabidop-sis thaliana,indicating that this pathway plays an important role in mediating the plant salt stress response.