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AGO 4 is specifically required for heterochromatic si RNA accumulation at Pol V‐dependent loci in Arabidopsis thaliana
Author(s) -
Wang Feng,
Axtell Michael J.
Publication year - 2017
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.13463
Subject(s) - small interfering rna , argonaute , biology , trans acting sirna , microbiology and biotechnology , effector , rna , genetics , gene
Summary In plants, 24 nucleotide long heterochromatic si RNA s (het‐si RNA s) transcriptionally regulate gene expression by RNA ‐directed DNA methylation (Rd DM ). The biogenesis of most het‐si RNA s depends on the plant‐specific RNA polymerase IV (Pol IV ), and ARGONAUTE 4 ( AGO 4) is a major het‐si RNA effector protein. Through genome‐wide analysis of sRNA ‐seq data sets, we found that AGO 4 is required for the accumulation of a small subset of het‐si RNA s. The accumulation of AGO 4 ‐dependent het‐si RNA s also requires several factors known to participate in the effector portion of the Rd DM pathway, including RNA POLYMERASE V ( POL V), DOMAINS REARRANGED METHYLTRANSFERASE 2 ( DRM 2) and SAWADEE HOMEODOMAIN HOMOLOGUE 1 ( SHH 1). Like many AGO proteins, AGO 4 is an endonuclease that can ‘slice’ RNA s. We found that a slicing‐defective AGO 4 was unable to fully recover AGO 4‐ dependent het‐si RNA accumulation from ago4 mutant plants. Collectively, our data suggest that AGO 4 ‐dependent si RNA s are secondary si RNA s dependent on the prior activity of the Rd DM pathway at certain loci.