title: DICER-LIKE 4 functions in trans-acting small interfering RNA biogenesis and vegetative phase change in Arabidopsis thaliana.
abstract: Arabidopsis thaliana contains four DICER-LIKE (DCL) genes with specialized functions in small RNA biogenesis for RNA interference-related processes. A mutant with defects in DCL4 was identified and analyzed for microRNA- and endogenous, small interfering RNA (siRNA)-related functions. The dcl4-2 mutant contained normal or near-normal levels of microRNAs (21 nt) and heterochromatin-associated siRNAs (24 nt). In contrast, this mutant lacked each of three families of 21-nt trans-acting siRNAs (ta-siRNAs) and possessed elevated levels of ta-siRNA target transcripts. The dcl4-2 mutant resembled an rna-dependent RNA polymerase 6 mutant in that both mutants lacked ta-siRNAs and displayed heterochronic defects in which vegetative phase change was accelerated. Double mutant analyses with dcl2-1, dcl3-1, and dcl4-2 alleles revealed hierarchical redundancy among DCL activities, leading to alternative processing of ta-siRNA precursors in the absence of DCL4. These data support the concept that plants have specialized and compartmentalized DCL functions for biogenesis of distinct small RNA classes.
authors.affiliation: Center for Gene Research and Biotechnology and Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA.
authors.forename: Zhixin
authors.initials: Z
authors.lastname: Xie
authors.forename: Edwards
authors.initials: E
authors.lastname: Allen
authors.forename: April
authors.initials: A
authors.lastname: Wilken
authors.forename: James C
authors.initials: JC
authors.lastname: Carrington
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017124:Conserved Sequence; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000096:biosynthesis* / Q000235:genetics; D043244:Ribonuclease III; D012260:Ribonucleases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D034741:RNA, Small Interfering; C504982:DCL4 protein, Arabidopsis; D012260:Ribonucleases; D043244:Ribonuclease III