Abstract
Tobacco microsomal ω-3 fatty acid desaturase (NtFAD3) catalyzes conversion of linoleic acid into α-linolenic acid. Most of transgenic tobacco plants with the NtFAD3 gene showed increased linolenate level. One of the overexpressing line is named S24. On the other hand, a transgenic line named S44 exhibited a lower level of leaf linolenate than the wild-type plants. In the S44 leaf tissues, expression of both transgene and endogenous counterparts was suppressed post-transcriptionally. In the most post-transcriptional gene silencings(PTGS), the coding region of a transgene is often methylated. Here we investigated the methylation pattern of the NtFAD3 transgene and the enodogenous NtFAD3 gene in the S44 plants. The plant DNA was digested by methylation-sensitive restriction enzymes and then the region containing the restriction-enzyme recognition site was amplified. The amplified pattern indicated that the transgene in the S44 plant was hypermethylated. To characterize the methylation site in more detail,bisulfite analysis is under investigation.
