| Summary: | 碩士 === 國立臺灣大學 === 植物科學研究所 === 94 === Tomatoes incur poor growth and fruit-set under hot-dry or hot-wet season in the tropics and sub-tropics, which is a major bottleneck impeding summer production. Recent studies concluded that impairment of pollen and anther development by elevated temperature contributes to decreased fruit set in tomatoes. Therefore, we would focus on anther and pollen in this study. The materials used in this study are the heat-tolerant tomato (CL5915-206D4-2-2-0) and the heat-sensitive tomato (L4783) offered by the Asian Vegetable Research and Development Center. Examinations of pollen viability by fluorescin diacetate (FDA) staining and pollen germinability by in vitro pollen germination and tube growth assays indicated that the heat stress can affect both of these traits, especially in the heat-sensitive tomato. From the suppression subtractive hybridization (SSH), the heat-induced genes from heat-tolerant tomatoes were isolated. Also, eight genes induced by the heat stress were further confirmed using the real-time PCR assays. After referring to other researches, REPRESSION OF SHOOT GROWTH (RSG) and LeHsc70-1 were chosen as the target genes. The complete mRNA sequence of LeHsc70-1 was found from the NCBI database, and that of RSG was obtained by RACE analysis. Real-time PCR with primers designed in the UTRs of these genes also indicated that both of two target genes are heat-inducible. 1152 bp-long promoter sequences of RSG gene from two different strains of tomato contained no heat shock element. 1229 bp-long promoter sequences of LeHsc70-1 gene from two different strains of tomatoes contained one heat shock element at the same position. Transgenic tomatoes were constructed with over-expressing target genes in the heat-sensitive tomato and knocking down target genes by RNAi in the heat-tolerant tomato to further understand if the target genes have any effect on the heat tolerance of tomato, but finally it was unsuccessful to obtain transgenic plants.
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