Transacting siRNA (tasiRNA) biogenesis in Arabidopsis is initiated
by microRNA (miRNA) –guided cleavage of primary transcripts. In
the case of TAS3 tasiRNA formation, ARGONAUTE7 (AGO7)–
miR390 complexes interact with primary transcripts at two sites,
resulting in recruitment of RNA-DEPENDENT RNA POLYMERASE6
for dsRNA biosynthesis. An extensive screen for Arabidopsis mutants...