| Summary: | 碩士 === 國立臺灣大學 === 昆蟲學研究所 === 105 === Tomato yellow leaf curl Thailand virus (TYLCTHV) is a member of the genus Begomovirus in the family Geminiviridae, and it is associated with tomato yellow leaf curl disease (TYLCD) in China, Myanmar, Thailand, and Taiwan. TYLCD is one of the major constraint on tomato production worldwide and often leads to 20-100% reduction in the yield of tomato particularly in tropical and subtropical areas. The genome of TYLCTHV is composed of bipartite DNA that are designated DNA-A and DNA-B. DNA-A carries six genes that encode the CP, the AV2 protein, the Rep protein, the TrAP, the REn protein, and the AC4 protein. DNA-B encodes two viral proteins, the NSP and the MP. To better understand the functions of the TYLCTHV proteins, green fluorescence protein (GFP) fused with each viral protein was expressed in planta by agroinfiltration. Further, the protein-protein interaction was examined by bimolecular fluorescence complementation (BiFC) assay which provides simultaneous protein interaction and localization data in living cells. The results showed that the GFP-CP fusion and the GFP-NSP fusion both localized exclusively to the nucleus with an accumulation in the nucleolus. The GFP-Rep fusion distributed throughout the nucleus excluding the nucleolus. The GFP-AV2, GFP-TrAP, the GFP-AV2, GFP-TrAP, GFP-REn, GFP-AC4, and GFP-MP fusions localized to both the cytoplasm and the nucleus. My results demonstrated that the subcellular localizations of the TYLCTHV proteins in the virus-infected plant leaves were identical to those in the healthy plant leaves. Besides, none of the protein-protein interactions of TYLCTHV were detected by BiFC assay. The results of the unchanged subcellular localizations of the TYLCTHV proteins in the healthy and in the TYLCTHV-infected N. benthamiana leaves are in agreement with the results of no protein-protein interactions examined by BiFC assay. Viral protein localizations in host cells provides valuable information about the biological roles of viral proteins. More studies are needed to further understand the relationship between the TYLCTHV proteins and their interactions with host proteins. The information will help us to further understand the molecular mechanisms that underlie the processes of virus replication, movement, and infection.
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