Expressional Analysis And Functional Characterization Of PGABH And AspRS In Arabidopsis

The Arabidopsis PGABH (Post Germination ABA Hypersensitive Gene) is a function-unknown gene. Aminoacyl-tRNA synthetase is a kind of enzyme which can catalyze the esterification reaction between specific amino acids or their precursors and the corresponding tRNA,to form aminoacyl-tRNA. Recent studies show that the aminoacyl-tRNA synthetase also has functions on regulation of gene expression, regulation of amino acid synthesis, and signal transduction. Aspartyl-tRNA synthetase (AspRS) belongs to classâ…¡aminoacyl-tRNA synthetase, there are few studies on the new functions of AspRS in plants. In this study, we use PGABH knockout mutant pgabh-1and AtAspRS-overexpressing Arabidopsis plants to analyze the functions of PGABH and AtAspRS.The main results about PGABH are as follows:1. PlantCARE analysis found PGABH promoter contains an ABRE-like element which is related with ABA signal response and AAAC motif,G-Box,Sp1 motif,which is related with light response. Tissue expression pattern analysis showed PGABH mainly expressed in the green tissues of Arabidopsis . The expression of PGABH increased sharply during early cotyledon growth, ABA treatment inhibited its increase. These results showed that the PGABH may be involved in the ABA-mediated early cotyledon growth and light regulation of flowering process.2. To study the function of PGABH, we obtained PGABH knockout mutants pgabh-1. The germination experiment results showed that ABA inhibited the early cotyledon greening process of pgabh-1. 3. pgabh-1 showed small leaf, early flowering phenotypes in long-day conditions. RT-PCR results showed that the deletion of PGABH altered the expression level of CO and FT, indicating that PGABH may regulate the expression of CO and FT to affect flowering time.The main results about AtAspRS are as follows:1. Tissue expression pattern analysis showed that AtAspRS expressed mainly in vascular tissue, apical portion and lateral roots.2. AtAspRS-overexpressing Arabidopsis plants showed phenotype of etiolation, short inflorescence axis, abortion and eventually dead under normal conditions. The phenotype occurs mainly during the seedling stage, bolting and silique maturity. The emergence rate of etiolation is related to the expression level of AtAspRS. Chlorophyll content analysis showed that the level of chlorophyll a was decreased in overexpression AtAspRS transgenic plants, the overexpression of AtAspRS affected the synthesis of chlorophyll a, or accelerate its degradation.3. The microarray data displayed that,the expression levels of 6913 gene were changeed sharply.These genes are involved in stress response, growth and development, biological and abiotic stimulus response, protein metabolism and gene transcription process. There were 23 chloroplast gene expression show a downward trend. These results demonstrate the AtAspRS overexpression affects the synthesis and degradation of chlorophyll.