Expression of rice heat stress transcription factor OsHsfA2e enhances tolerance to environmental stresses in transgenic Arabidopsis
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Plant growth and crop yields are limited by high-temperature stresses. In this study, we attempted to isolate the rice genes responsible for high-temperature stress tolerance using a transformed Arabidopsis population expressing a full-length cDNA library of rice. From approximately 20,000 lines of transgenic Arabidopsis, we isolated a thermotolerant line, R04333, that could survive transient heat stress at the cotyledon stage. The rice cDNA inserted in R04333 encodes OsHsfA2e, a member of the heat stress transcription factors. The thermotolerant phenotype was observed in newly constructed transgenic Arabidopsis plants expressing OsHsfA2e. Among 5 A2-type HSF genes encoded in the rice genome, four genes, including OsHsfA2e, are induced by high temperatures in rice seedlings. The OsHsfA2e protein was localized to the nuclear region and exhibited transcription activation activity in the C-terminal region. Microarray analysis demonstrated that under unstressed conditions transgenic Arabidopsis overexpressing OsHsfA2e highly expressed certain stress-associated genes, including several classes of heat-shock proteins. The thermotolerant phenotype was observed not only in the cotyledons but also in rosette leaves, inflorescence stems and seeds. In addition, transgenic Arabidopsis exhibited tolerance to high-salinity stress. These observations suggest that the OsHsfA2e may be useful in molecular breeding designed to improve the environmental stress tolerance of crops.
KeywordsArabidopsis FOX-hunting system Heat stress transcription factor High-temperature stress Rice
Full-length cDNA overexpressing
Green fluorescent protein
Heat stress transcription factor
We thank Dr. Francis M. Mathooko (Jomo Kenyatta University, Kenya) for the careful perusal of this manuscript. We also thank Dr T. Nakagawa (Shimane University, Japan) for providing the pGWB6 plasmid and Dr M. Mori (National Institute of Agrobiological Sciences) for providing the rice seed. This work was supported in part by Special Coordination Funds for Promoting Science and Technology (Science and Technology Agency of Japan).
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