Characterization and application of promoter activities associated with the multipartite ssDNA genome of plant Nanovirus.

点击翻译按钮获取中文摘要

Predicted promoter regions of Milk vetch dwarf virus (MIDV) components (C1-C11) were isolated and fused with a β-glucuronidase (GUS) reporter gene and the characteristics of the promoters were examined. In transgenic tobacco calli, promoters of MDV C4,C5 and C7,C6 and C8 generated a stronger level of GUS expression than the Cauliflower mosaic virus 35S RNA promoter (P35S). In leaves of transgenic tobacco plants, the promoters of C5 and C8 conferred a level of GUS activity comparable to that of P35S. Histochemical GUS analysis showed that the promoters of C4-C9, the latter encoding a capsid protein, were active in phloem and meristematic tissue. The promoter of C8 was also active in mesophyll and cortex cell types. The usefulness of the MDV-C8 promoter (PMC8) was further confirmed by driving NPTII for selection of kanamycin-resistant tobacco plants with improved transformation efficiency. PMC8 was also effective in transgenic rice plants. Thus, PMC8 is useful as an alternative to P35S in both dicotyledonous and monocotyledonous plants, especially for gene expression in proliferating tissues. During the period of present research, the host range of MDV was further examined, and it was revealed that, besides the known legume plant hosts, MDV systemically infect several non-legume plants including Spinacia oleracea, Stellaria media and Arabidopsis thaliana. These facts have implications for the etiology of MDV, for which the summer hosts have not known.