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Functional characterization of Arabidopsis ARGONAUTE 3 in reproductive tissues
Author(s) -
Jullien Pauline E.,
Grob Stefan,
Marchais Antonin,
Pumplin Nathan,
Chevalier Clement,
Bonnet Diane M. V.,
Otto Caroline,
Schott Gregory,
Voinnet Olivier
Publication year - 2020
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.14868
Subject(s) - argonaute , biology , arabidopsis , genetics , gene silencing , gene , rna interference , rna , microbiology and biotechnology , mutant
SUMMARY Arabidopsis encodes 10 ARGONAUTE (AGO) effectors of RNA silencing, canonically loaded with either 21–22 nucleotide (nt) long small RNAs (sRNAs) to mediate post‐transcriptional gene silencing (PTGS) or 24 nt sRNAs to promote RNA‐directed DNA methylation. Using full‐locus constructs, we characterized the expression, biochemical properties and possible modes of action of AGO3. Although AGO3 arose from a recent duplication at the AGO2 locus, their expression patterns differ drastically, with AGO2 being expressed in both male and female gametes whereas AGO3 accumulates in aerial vascular terminations and specifically in chalazal seed integuments. Accordingly, AGO3 downregulation alters gene expression in siliques. Similar to AGO2, AGO3 binds sRNAs with a strong 5′ adenosine bias, but unlike Arabidopsis AGO2, it binds 24 nt sRNAs most efficiently. AGO3 immunoprecipitation experiments in siliques revealed that these sRNAs mostly correspond to genes and intergenic regions in a manner reflecting their respective accumulation from their loci of origin. AGO3 localizes to the cytoplasm and co‐fractionates with polysomes to possibly mediate PTGS via translation inhibition.