Prelimilary Physiological Studies On The Psrp-3 Gene Anti-sense Arabidopsis Mutant

Six ribosomal proteins are specific to higher plant chloroplast ribosomes. These proteins are plastid-specific ribosomal proteins (PSRPs). PSRP-3, on the small subunit and unassociated with rRNA, is an evolutionarily conserved chloroplast ribosomal protein It is the higher plant orthologue of protein YCF65 (ycf65 gene product) in cyanobacteria. It is proposed that PSRP-3 acts as regulator to participate in light-dependent chloroplast protein synthesis, however the mechanism is not resolved yet. In our research we use anti-sense technology to study the physiological and biochemical characerisics to understand the function and mechanism of protein PSRP-3.The main results were reported as following:1. Psrp-3 anti-sense cDNA was amplified from Arabidopsis thaliana by RT-PCR using a pairs of specific primers containing 5' end of two poly-linkers XbaI and SacI. DNA sequence analysis indicates Psrp-3 (GeneBank Accession No.ATlG68590) consists of 743bp, encoding a polypeptide of 166 amino acids. The first 44 amino acids are signal peptides for targeting to the chloroplast.2. The product of PCR digested by Xbal/SacI was ligated to pBI121 vector, then the recombinant plasmid pBI121-anti-sense Psrp-3 was obtained. The recombinant plasmid pBI121-anti-sense Psrp-3 was confirmed by PCR and sequence alignment3. The recombinant plant expression vector containing pBI 121-anti-sense Psrp-3 was constructed and transferred into A. tumefaciens EHA105 by triparent mating method. Arabidopsis thaliana was tranformed with the recombinant A. tumefaciens, and the transformants were identified by Kan resistance and examined by PCR.4. The physiological and biochemic alanalysis of transgenic plants showed that there were little difference to chlorophyll contents and ratio of chl a to chl b (Chl a/b) between the WT and transgene plant of Arabidopsis. The growth kinetics and chloropyll fluorescence analysis showed retarded growth rate of transgenic Arabidopsis. Thus, these results indicated that PSRP-3 is likely to play important roles in chloroplast development.