Abstract:

Transgenic tobacco (Nicotiana tabacum L. cv. Xanthi) plants which express coat protein (CP) gene (cp) of potato virus X (PVX) were generated via Agrobacterium tumefaciens-mediated gene transfer. Northern blotting analysis indicated that cp silencing happened in three transformants, and Run on assay showed that the cp silencing was at post-transcriptional level. The result of cp methylation assay showed different degree of methylation existed in coat protein gene coding sequences. cp methylation was also analyzed during virus-induced gene silencing (VIGS), and results suggested that methylation pre-existed in cp non-silenced transgenic plants, while virus infection increase the methylation degree, which indicated DNA methylation in VIGS was not a de novo DNA methylation process.

Key words: potato virus X, coat protein, transgenic plant, DNA methylation, post-transcriptional gene silencing