| Water stress affects productivity, disease tolerance, and enological characteristics of grape. Florida Hybrid Bunch grape are developed through hybridization of local grape spp with Vitis vinifera. These cultivars are mostly grown in southeast region of United States. Deficit of rain in Florida region developed interest among grape growers for water use efficient grape cultivars. The goal of this research is to identify genes and proteins differentially expressed in response to water stress and to correlate these changes to biochemical pathways affecting the enological characteristics. Investigating gene transcripts and their protein products will allow us to find correlation between genes and their involvement in water stress tolerance. In this study, Florida Hybrid Bunch Grape cultivar 'Suwannee' plants were used which were maintained under green house conditions. Water stress was emulated by withholding of irrigation. The leaf samples were collected from both irrigated and stressed plants at 5, 10, 15 and 20 day interval. Total RNA was isolated from leaf tissue and cDNAs were obtained. cDNAs were subjected to subtractive hybridization and obtained over 200 PCR products from control and water stressed leaf tissues. Cloning, sequencing and transcript analysis revealed that, 54 genes related to drought and defense regulated pathways out of 125 characterized transcripts. Proteins were extracted from leaf tissue with trichloroacetic acid/acetone and separated by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). The proteins were sequenced in LC/Mass Spectrophotometer. Differentially expressed proteins to water stress were sequenced in LC/Mass Spectrophotometer. We found that, most differentially expressed genes include sucrose synthase, actin, isoprene synthase, ABF3, SNF1 related protein kinase, WRKY type transcription factors, AP2, ASR2, glyoxalase I and, cytochrome b. These factors play significant role in cell permeability, transportation, photosynthesis and, plant maintenance during osmotic stress. We have found that ribulose bisphosphate carboxylase, glyceraldehyde 3-phospho dehydrogenase and phosphoribulokinase which play major role in photosynthesis were suppressed in response to water stress in Florida hybrid bunch. We conclude that water stress affects expression of cDNAs associated with defense and drought regulated functions. Such profiling studies will be used to explicate specific pathways disconcerted by water deficit treatments, and in the identification of varietal differences. |
