| Summary: | 碩士 === 國立中興大學 === 生物科技學研究所 === 93 === A pollen-specific protein, LLA23, accumulates at the later stage of pollen maturation in lily（Lilium longiflorum Thunb. cv. Snow Queen） anthers. LLA23 is a member of ABA-, stress-, and ripening-induced (ASR) proteins. 35S::LLA23 lines in Arabodopsis exhibit drought and salt tolerance and show insensitivity to ABA. T4 transgenics were used to analyze sugar signal transduction. When treated with low to intermediate (6.9~167mM) concentrations of glucose or mannitol, difference in germination rate is insignificant between wild-type (Col-0) and transgenic plants, but the germination rate decreases as the glucose concentration increases. High level of glucose (333mM) or mannitol inhibits seed germination of both wild- type and transgenics. However, the germination rate of 35S::LLA23 plants is higher than wild-type. 35S::LLA23 exhibits reduced insensitivity to glucose, suggesting the involvement of LLA23 in the pathway of glucose signal transduction. The seedling growth of wild type plants is arrested under high concentration of glucose while 35S::LLA23 seedlings keep growing. It suggests that 35S::LLA23 seedlings display resistance to glucose at the stage of post-germination. RT-PCR analysis shows different patterns of stress-related genes in transgenic plants under the treatment of 333 mM glucose. It suggests that LLA23 may act as a regulator controlling the expression of these stress-related genes. When treated with ethylene precursor, 1-aminocyclo-propane-1-carboxylic acid (ACC), 35S::LLA23 plants show reduced sensitivity in exaggerated curvature of the apical hook, shortening and radial swelling of the hypocotyl and an inhibition of root elongation. Therefore, it suggests that LLA23 may also involve in ethylene signal transduction. To investigate the possible drought tolerance of economic plants, we have transformed the LLA23 gene into tobacco by Agrobacterium. Six T0 transgenic lines expressing the LLA23 protein are confirmed by PCR and immunoblot analyses. The homozygote plants will be further selected for drought resistance analysis.
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