| Summary: | 碩士 === 國立中央大學 === 生物資訊與系統生物研究所 === 97 === Late embryogenesis abundant (LEA) proteins were initially found in the stage of embryo maturation. According to amino acid sequence similarities and conserved motifs, the LEA proteins can be separated into more than five groups. It is known that abscisic acid (ABA), salt, drought or cold stress can induce expression of the lea genes, conferring stress tolerance to plant cells. LEA proteins have been shown to involve in binding and replacement of water molecule, ion sequestration, maintaining of protein or cell membrane structure, and development regulation. Group 3 LEA proteins are characterized by 11-mer amino acid conserved tandem repeats (TEAAKQKAAET) and considered as the stress proteins. Barley HVA1, a member of group 3 LEA proteins, has been reported that it can improve stress tolerance in transgenic plants. However, its exact physiological functions still remain unclear. In this study we used the sequence BLAST to search Group 3 LEA protein orthologues in rice genome database and identify five lea3-like genes. They are AP004018/BAD19162, AP003381/BAB86507, AC073556/AAL84288, AC098833/AAU43988, AP000836/BAD81113 (gene/protein accession number). Here we were trying to characterize their gene sequence organization and expression patterns during developmental stages and environmental stresses. The results showed that these LEA genes played important roles on regulation of plant growth and response for varied stresses, and tissue-specific expression in root, stem, leaf, and seed. Furthermore, cellular localization analysis of the AP004018-GFP, AP003381-GFP, AC073556-GFP, AC098833-GFP, and AP000836-GFP fusion proteins in onion epidermal cells indicated that rice group 3 LEA proteins could be in nucleus (AP003381, AC073556 under ABA or 4℃ treatment), cytoplasm (AC073556, AC098833 under ABA; AP004018, AC073556, AC098833 under NaCl; AP004018, AC098833 under 4℃ treatment), or membrane structure (AC073556 under ABA and NaCl; AP004018, AP003381, AC073556, and AC098833 under 4℃ treatment ), whereas these fusion proteins localize in either nucleus or cytoplasm under non-stress conditions.
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