title: Rice RNA-dependent RNA polymerase 6 acts in small RNA biogenesis and spikelet development.
abstract: Higher plants have evolved multiple RNA-dependent RNA polymerases (RDRs), which work with Dicer-like (DCL) proteins to produce different classes of small RNAs with specialized molecular functions. Here we report that OsRDR6, the rice (Oryza sativa L.) homolog of Arabidopsis RDR6, acts in the biogenesis of various types and sizes of small RNAs. We isolated a rice osrdr6-1 mutant, which was temperature sensitive and showed spikelet defects. This mutant displays reduced accumulation of tasiR-ARFs, the conserved trans-acting siRNAs (tasiRNAs) derived from the TAS3 locus, and ectopic expression of tasiR-ARF target genes, the Auxin Response Factors (including ARF2 and ARF3/ETTIN). The loss of tasiR-mediated repression of ARFs in osrdr6-1 can explain its morphological defects, as expression of two non-targeted ARF3 gene constructs (ARF3muts) in a wild-type background mimics the osrdr6 and osdcl4-1 mutant phenotypes. Small RNA high-throughput sequencing also reveals that besides tasiRNAs, 21-nucleotide (nt) phased small RNAs are also largely dependent on OsRDR6. Unexpectedly, we found that osrdr6-1 has a strong impact on the accumulation of 24-nt phased small RNAs, but not on unphased ones. Our work uncovers the key roles of OsRDR6 in small RNA biogenesis and directly illustrates the crucial functions of tasiR-ARFs in rice development.
authors.affiliation: State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Xianwei
authors.initials: X
authors.lastname: Song
authors.forename: Dekai
authors.initials: D
authors.lastname: Wang
authors.forename: Lijia
authors.initials: L
authors.lastname: Ma
authors.forename: Zhiyu
authors.initials: Z
authors.lastname: Chen
authors.forename: Pingchuan
authors.initials: P
authors.lastname: Li
authors.forename: Xia
authors.initials: X
authors.lastname: Cui
authors.forename: Chunyan
authors.initials: C
authors.lastname: Liu
authors.forename: Shouyun
authors.initials: S
authors.lastname: Cao
authors.forename: Chengcai
authors.initials: C
authors.lastname: Chu
authors.forename: Yuezhi
authors.initials: Y
authors.lastname: Tao
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Cao
mesh_terms: D002874:Chromosome Mapping; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D015723:Gene Library; D005816:Genetic Complementation Test; D059014:High-Throughput Nucleotide Sequencing; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D012275:Oryza / Q000166:cytology / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D035261:Plant Components, Aerial / Q000166:cytology / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000166:cytology / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D030821:Plants, Genetically Modified; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism*; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics / Q000378:metabolism*; D036226:Seedlings / Q000166:cytology / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D017423:Sequence Analysis, RNA; D013696:Temperature; D019076:Transgenes
chemical_list: D035683:MicroRNAs; D010940:Plant Proteins; D018749:RNA, Plant; D034741:RNA, Small Interfering; D012324:RNA-Dependent RNA Polymerase