โ Scribed by Sean Chapman; Tony Kavanagh; David Baulcombe
No coin nor oath required. For personal study only.
The suitability of potato virus X (PVX) as a gene vector in plants was tested by analysis of two viral constructs. In the first, the GUS gene of Escherichia coli was substituted for the viral coat protein gene. In the second, GUS was added into the viral genome coupled to a duplicated copy of the viral promoter for the coat protein mRNA. The viral construct with the substituted coat protein gene accumulated poorly in inoculated protoplasts and failed to spread from the site of infection in plants. These results suggest a role for the viral coat protein in key stages of the viral infection cycle and show that gene replacement constructs are not suitable for the production of PVXโbased gene vector. The construct with GUS coupled to the duplicated promoter for coat protein mRNA also accumulated less well in protoplasts than the unmodified PVX, but did infect systemically and directed high level synthesis of GUS in inoculated and systemically infected tissue. Although there was some genome instability in the PVX construct, much of the viral RNA in the systemically infected tissue had retained the foreign gene insertion, especially in infected Nicotiana clevelandii plants. These data point to a general utility of PVX as a vector for unregulated gene expression in plants.
๐ SIMILAR VOLUMES
The gene for human epidermal growth factor (hEGF) was chemically synthesized and used for expression in transgenic potato. The hEGF coding sequence was modified by PCR to introduce ATG start codon and fused either to the 35S cauliflower mosaic virus promoter or to the patatin class I promoter. The h
Patatin is a family of lipid acyl hydrolases that accounts for 30 to 40 ~o of the total soluble protein in potato tubers. Class-I patatin genes encode 98 to 99~ of the patatin mRNA in tubers, but are not normally expressed in other tissues. They are not totally 'tuber-specific'; however, since they