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Abstract
Abscisic acid (ABA) is a plant growth hormone that plays a key role in many physiological and developmental processes in plant cells. The present investigation examines differential gene expression in Vicia villosa under ABA treatment, in an attempt to identify stress genes whose expression is regulated by ABA and define their function. In order to accomplish that aim, Vicia villosa shoots were treated with ABA for 3 and 24 hr. Total cellular RNA from treated and untreated shoots are subjected to differential display reverse transcription (DDRT) technique in order to detect differentially expressed genes and cloning their corresponding cDNAs in a pGEM-T plasmid for amplification and sequencing. Sixty fragments were chosen from the differentially displayed cDNA fragments and classified into 4 groups according to their expression patterns (up or down regulation by ABA treatment). The sequence of 34 of the DD-cDNA fragments was determined and the corresponding stress genes were identified using a bioinformatic approach. The results of the database sequence alignment identified 7 fragment sequences with significant homology to the following genes and/or proteins: Arabidopsis thaliana NADH dehydrogenase; Medicago truncatula zinc finger CCHC type; Medicago truncatula, Phaseolus vulgaris, Glycine max NBS-LRR plant resistance, Psychrobacter sp. arginine acetyl transferase, Clostridium acetobutylicum phosphoenolpyruvate synthase, Arabidopsis thaliana ATP binding/ uracil phosphoribosyl transferase and Arabidopsis thaliana heat shock protein binding. The significance of the function of the identified differentially expressed genes was discussed in relation to their possible roles as stress genes. Results of this work are a first step towards understanding the molecular mechanism of ABA and the elucidation of the biochemical changes- at a molecular level- that occur in Vicia villosa plant in response to environmental stress. The identified stress genes could be ultimately used to improve the stress (abiotic and/or biotic) tolerance of economic crops by gene manipulation.