| Summary: | 碩士 === 國立中央大學 === 生命科學研究所 === 98 === Rice is one of the important crops supplying food for more than half of the global population. However, yield of rice is not enough because of climatic changes and more and more population on the world recently. Environmental stresses are also a major source of problems for crop growth. High temperature is a major environmental stress affecting yield of crop. Grain yield declined by 10% for each 1℃ increase in the most suitable temperature for rice. Abscisic acid (ABA), a phytohormone, functions in seed maturation and accumulates in response to chilling, drought, and salt stresses. To improve stresses tolerance and preserve yield of rice, we identified a both heat- and ABA-responsive gene, OsRZFP1 (cDNA accession number is AK068005), from oligo microarray expression profiling of rice leaves. The deduced amino acid sequence of OsRZFP1 contains an N-terminal Pfam:zf-CHY domain and a C-terminal RING-H2 zinc finger signature. Using reverse transcripts polymerase chain reaction (RT-PCR) to analyze tissue specificity and expression pattern of OsRZFP1, we found that OsRZFP1 specifically expressed in rice shoot but not in root. Furthermore, the results also indicated that OsRZFP1 showed three-fold heat- and two-fold ABA-inducibility in rice seedling, separately. Although zinc finger protein is usually characterized as transcription factor, subcellular localization of OsRZFP1-GFP in Arabidopsis protoplasts and onion epidermal cells showed OsRZFP1 localized not only in the nucleus but cytoplasm. To study the role of OsRZFP1 for resistance to heat and ABA stresses, we transformed sense strands and antisense fragments of OsRZFP1 into rice and Arabidopsis to overexpress and knock down the transcripts. Temperature tolerance was increased in rice overexpression OsRZFP1 and decreased in OsRZFP1 knock down plants. Moreover, gain of OsRZFP1 function increased not only stomatal closure rate but cold and salt tolerance in transgenic Arabidopsis. Collectively, these results indicated that OsRZFP1 functions in both heat and ABA stresses response. It may provide a genetic engineering approach for improving stresses tolerance in crops.
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