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Title: AGO 4 is specifically required for heterochromatic si RNA accumulation at Pol V‐dependent loci in Arabidopsis thaliana

In plants, 24 nucleotide long heterochromatic siRNAs (het‐siRNAs) transcriptionally regulate gene expression byRNA‐directedDNAmethylation (RdDM). The biogenesis of most het‐siRNAs depends on the plant‐specificRNApolymeraseIV(PolIV), andARGONAUTE4 (AGO4) is a major het‐siRNAeffector protein. Through genome‐wide analysis ofsRNA‐seq data sets, we found thatAGO4is required for the accumulation of a small subset of het‐siRNAs. The accumulation ofAGO4‐dependent het‐siRNAs also requires several factors known to participate in the effector portion of the RdDMpathway, includingRNA POLYMERASEV (POLV),DOMAINS REARRANGED METHYLTRANSFERASE2 (DRM2) andSAWADEE HOMEODOMAIN HOMOLOGUE1 (SHH1). Like manyAGOproteins,AGO4 is an endonuclease that can ‘slice’RNAs. We found that a slicing‐defectiveAGO4 was unable to fully recoverAGO4‐dependent het‐siRNAaccumulation fromago4mutant plants. Collectively, our data suggest thatAGO4‐dependent siRNAs are secondary siRNAs dependent on the prior activity of the RdDMpathway at certain loci.

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Author(s) / Creator(s):
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Date Published:
Journal Name:
The Plant Journal
Page Range / eLocation ID:
p. 37-47
Medium: X
Sponsoring Org:
National Science Foundation
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