Sense transgene-induced post-transcriptional gene silencing in tobacco compromises the splicing of endogenous counterpart genes.

Sense transgene-induced post-transcriptional gene silencing (S-PTGS) is thought to be a type of RNA silencing in which ARGONAUTE1 directs the small interfering RNA (siRNA)-mediated cleavage of a target mRNA in the cytoplasm. Here, we report that the altered splicing of endogenous counterpart genes is a main cause for the reduction of their mature mRNA levels. After the S-PTGS of a tobacco endoplasmic reticulum ω-3 fatty acid desaturase (NtFAD3) gene, 3'-truncated, polyadenylated endo-NtFAD3 transcripts and 5'-truncated, intron-containing endo-NtFAD3 transcripts were detected in the total RNA fraction.