| Summary: | 碩士 === 臺灣大學 === 植物科學研究所 === 95 === Plants often meet many biotic and abiotic stresses throughout their life cycle. Assortments of genes with diverse functions are influenced by dehydration stresses. Most of their gene products may function in stress responses and tolerance at the cellular level. The predominant mechanism for controlling plant gene expression is regulated at the transcriptional level and is mediated by transcription factors (TFs). According to the microarray data of (Kamiya et al., 2002), we selected a dehydration-induced gene At2g20880 to study more detail in this paper. At2g20880 contains one highly conserved AP2 domain and belongs to DREB subfamily. Using RT-PCR, we found At2g20880 gene was expressed in root, stem, leaf, but has lower expression levels in flowers. We found that this gene was highly inducible by dehydration but not by high temperature and abscisic acid. The At2g20880 RNAi transgenic plants and At2g20880-overexpressing plants exhibited the same phenotype as wild-type under normal growth conditions. At2g20880-overexpressing plants, however, survived better than wild-type under water deficient condition. The expression of At2g20880 gene was not influenced by ABA treatment; and there is no difference in seed germination rate and root growth between At2g20880-overexpressing transgenic plants and wild type in the presence of ABA, suggesting that the ABA sensitivity of At2g20880-overexpressing transgenic plants was not altered. Localization study using a fusion protein consisting of the full length of At2g20880 coding region and GFP fusion under the control of 35S promoter revealed that the GFP fluorescence was detected in the cytoplasm but not in the nucleus. In this study, we found At2g20880 is involved in dehydration-induced signaling transduction in an ABA-independent manner. Overexpressing At2g20880 gene enhanced dehydration tolerance in Arabidopsis. Our study provides evidence that At2g20880 is a positive regulator in dehydration stress response.
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