| Summary: | 碩士 === 國立臺灣大學 === 農藝學研究所 === 91 === Rice (Oryza sativa L.) is one of the major crops in the world. The total harvested area is about 150 million ha. and the production is around 600 million Mt in 2002. Currently, most of farmers fertilize with high concerntration nitrogen to increase rice production.However, the fertilizer with high doesage of nitrogen increase the probability that rice plants are attacked by insects and pathogen.This is a serious problem in all rice-growing countries, especially in Asia. Therefore, it is important to improve the tolerance or resistance for insects attack and pathogen infection to increase the production
of rice.
Osmotin, a 26 kDa protein, was accumulated obviously in plant cells under osmotic stress. Since the results get from osmotin-overexpressed transgenic potato and tobacco suggested that osmotin may help plant to defense pathogen infection. An effort was made to study whether overexpression of the osmotin gene in rice could enhance environmental stress tolerance of rice. Osmotin gene was controlled under a ABA-induced promoter, ABRC1, and transferred into rice (Tainung 67) with Agrobacterium-mediated transformation. According to the Southern blot hybridization results, 16 of 24 T0 transgenic lines contained one copy of osmotin gene, 7 lines contained two copies of osmotin gene and 1 line was inserted three copies of osmotin gene into rice chromosomes. Moreover, stable expression of the osmotin gene was observed in T0, T1 and T2 transgenic plants. In addition, the expression of osmotin gene is enhanced slightly by ABA treatment. To test resistance of T1 transgenic plants to Xanthomonas campestris, the disease symptom of transgenic rice is slighter than that of control plants. On the other hand, the ability of transgenic rice to resist blast disease was not improved. Results also showed the tolerance to salt stress was increased with overexpression of osmotin in transgenic rice. Conclusion, these results suggested osmotin could be an important role to help rice resist bacteria leaf blight and salt stress.
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