Development of plant virus vectors for genetic engeering in fruit frees

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Apple latent spherical virus (ALSV) has isometric virus particles, c. 25 nm in diameter, and contains two ssRNA species (RNA1 and RNA2) and three capsid proteins. The virus is what is called a latent virus that infects most host plants symptomlessly. The aims of the research are the development of plant virus vectors for expressing foreign genes in plants and the establishment of the genetic engineering system in fruit trees by the virus vectos. The results were summarized as follows.(1)Construction of the ALSV-RNA2 vectors.Infectious cDNA clones of ALSV-RNAs were successfully constructed and modified into viral vectors for stable expression of foreign genes in plants.(2)Expression of foreign genes in plants using ALSV vectors.The ALSV vector which expresses green fluorescence protein (GFP) has been constructed and used for the tracing of cell-to-cell and long distance movement of the virus in infected plants. ALSV expressing yellow and cyan fluorescent proteins (YFP and CFP) have also … More been constructed and used investigate the interaction of populations of identical, but differently tagged viruses in doubly infected plants. The results indicated that ALSV-YFP and ALSV-CFP were always distributed separately in infected leaves. The ALSV vector could also express an antifungal peptide (diapausin) from an insect in plants.(3)Use of ALSV vectors for inducing RNA silencing of a transgene and endogenous genes in plants.ALSV expressing GFP infection efficiently triggered virus-induced gene silencing of a transgene (GFP gene) in transgenic tobacco plants. We also successfully silenced the phytoene desaturase (PDS), sulfur (SU), and proliferating cell nuclear antigen (PCNA) genes in four Nicotiana species (N.tabacum, N.benthamiana, N.occidentalis, and N.glutinosa) and Arabidopsis thaliana plants by ALSV vectors.(4)Promotion of flowering in plants Infected with ALSV expressing flowering locus T (FT) gene of Arabidopsis thaliana.The infection of ALSV expressing FT resulted in the strong promotion of flowering in four Nicotiana species, petunia, and A.thaliana. Less