Fig. 5.

A proposed model for the IR-mediated dynamic regulation of the HaWRKY6 locus. In Cots, transcription of the bidirectional HaWRKY6 promoter yields a hairpin ncW6 transcript, which is processed into siRNAs that trigger RdDM on its own locus (a). An additional DNA methylated region downstream from the HaWRKY6 3′UTR stabilizes the formation of a loop encompassing the whole locus (b), potentially promoting an efficient RNAPII usage and transcription of the HaWRKY6 gene (c). Methylation of the ncW6 sequence and loop formation are associated with a change in the direction of transcription, which, in turn, reduces sRNA abundance and methylation, resulting in loop dissolution (d). In leaves, the methylation of a region within the fourth intron, together with reduced methylation of region 3, (e) triggers the formation of an intragenic chromatin loop that blocks RNAPII transcription (f). The red pins show methylated regions.