Study On The Function Of Subunit C Genes Of Vacuolar H～+-ATPase In Arabidopsis Thaliana

The plant vacuolar H+-ATPase (V-ATPase ) is a membrane-bound transporter protein, it uses the energy released during cleavage of theγ-phosphate of cytosolic ATP to pump protons into the vacuolar lumen and acidify the vacuole, thereby creating an electrochemical H+-gradient which is the driving force for a variety of transport events of ions and metabolites and so influencing turgor, cell expansion and guard cell movement. On the other hand, under stress conditions such as drought, salinity, cold, the V-ATPase make a key role. However, the related mechanisms are unknowned.V-ATPase of Arabidopsis contains 13 distinct subunits organized into two large subcomplexes: The cytosolic V1 and membrane V0. Subunit c coded by five genes, is a major component of V0 sector, forms the proton conductance pathway. In addition, subunit c is also the most sensitive component when plants under stress conditions. Study on the functions and especially the mechainisms of subunit c of V-ATPase in Arabidopsis, has significant importance for theory and practice.In this paper, a RT-PCR system for assaying the expression of VHA-c genes, is esteblished. We made a detailed study on the VHA-c genes response to water stress, salinity and exogenous phytohormones(IAA, GA, SA, MeJA, ABA, ACC). Our results showed that:1. Comparing the gene sequences, cDNA sequences, 3ˊ-UTR and amino acid sequences of five VHA-c genes by Vector NTI and Plantcare software, we found the gene sequences and 3ˊ-UTR of VHA-c genes sharing very low similarity, but the cDNA sequences highly conserved, and the polypeptides coded by VHA-c genes have 97% sequence identity, this may be an important adaption mechainism to stress conditions in arabidopsis.2. We established the RT-PCR system to detect the expression of VHA-c genes, and verified the responses of VHA-c genes to plant hormones, salinity and water stress. Under stress conditions, VHA-c genes have higher expressions, and reach the highest expression level at 12 hours after stress. The expression of VHA-c genes are regulated by exogenous plant hormones. This indicates that VHA-c genes may be involved in hormone signal transduction, and may have roles in plant lifecycle, wounding and pathogen infection. Moreover, VHA-c genes respond to water stress and salinity, indicated that it participated in plant resistance to abiotic stresses.