The Functions Of AtJ50 Gene In Arabidopsis Thaliana

J-protein is a kind of protein which contains J-domain. Some of them act as molecular chaperones or heat shock proteins. A total of 94 J-proteins were identified in the genome of the model flowering plant Arabidopsis thaliana, implying that J-proteins is likely to play important role in growth and development of plant. At present, the researches about J-proteins are mainly focus on the molecular chaperone. There is less report for function of J-proteins on growth, deveploment and adaptability to environmental stress. AtJ50 is one of the J-protein family members in Arabidopsis thaliana. Based on the result of sequence analysis, AtJ50 could be secreted to the apoplast. It has not been reported yet to the tissue and subcelluar localization of AtJ50, as well as its function on growth, development and tolerance to environmental stress. In this project, with the wile type Arabidopsis and T-DNA insertion mutant, we conducted some primary researches on the expression characteristic, the functions on growth, development and adaptability to the environmental stress.The expression of AtJ50 gene in different organs was detected by semi-quantitative PCR. The result showed that the expression level of AtJ50 gene was most high in leaves and flowers, less in roots and stems, least in siliques. The expression of AtJ50 gene on different development stages was also checked by semi-quantitative PCR. The result indicated that AtJ50 gene expressed on every developmental stage, but the expression level decreased with the plant’s caducity.We screened two homozygous T-DNA insertion mutants with two different insertion sites. There was only single T-DNA copy in both mutants. The result with RT-PCR showed that there was not full transcript of AtJ50 gene in mutants,. The phenotypes of AtJ50 mutants were observed and analyzed. The results indicated that there was no obvious difference on the rosette size, stem height and the development stage between wild type and AtJ50 mutants.Under the heat, cool, salt, drought condition, we detected the induced expression of AtJ50 gene in the wild type. The results showed that the expression of AtJ50 gene could be induced obviously during heat and salt stresses, induced slightly during drought stress. However, the expression of AtJ50 gene was not affected by cool stress. In addition, the tolerance of AtJ50 mutants was detected under various stresse conditions. The results showed that the viability of seedlings had no obvious differenece between wild type and AtJ50 mutants under heat, cool, freeze and drought stress conditions. However the viability of AtJ50 mutants was weaker and ratio of germination was also lower than wild type under salt stress. The results suggest that AtJ50 gene might be involved in the adaptation of plant to salt stress.In addition, we cloned the cDNA sequences and promoter sequences of AtJ50 gene, which is preliminary work for the further researchs including the tissue and subcellular localization and genetic transformation.