Ectopic DICER-LIKE1 expression in P1/HC-Pro Arabidopsis rescues phenotypic anomalies but not defects in microRNA and silencing pathways.
Expression of the viral silencing suppressor P1/HC-Pro in plants causes severe developmental anomalies accompanied by defects in both short interfering RNA (siRNA) and microRNA (miRNA) pathways. P1/HC-Pro transgenic lines fail to accumulate the siRNAs that mediate RNA silencing and are impaired in both miRNA processing and function, accumulating abnormally high levels of miRNA/miRNA* processing intermediates as well as miRNA target messages. Both miRNA and RNA silencing pathways require participation of DICER-LIKE (DCL) ribonuclease III-like enzymes. Here, we investigate the effects of overexpressing DCL1, one of four Dicers in Arabidopsis thaliana, on P1/HC-Pro-induced defects in development and small RNA metabolism. Expression of a DCL1 cDNA transgene (35S:DCL1) produced a mild gain-of-function phenotype and largely rescued dcl1 mutant phenotypes. The 35S:DCL1 plants were competent for virus-induced RNA silencing but were impaired in transgene-induced RNA silencing and in the accumulation of some miRNAs. Ectopic DCL1 largely alleviated developmental anomalies in P1/HC-Pro plants but did not correct the P1/HC-Pro-associated defects in small RNA pathways. The ability of P1/HC-Pro plants to suppress RNA silencing and the levels of miRNAs, miRNA*s, and miRNA target messages in these plants were essentially unaffected by ectopic DCL1. These data suggest that P1/HC-Pro defects in development do not result from general impairments in small RNA pathways and raise the possibility that DCL1 participates in processes in addition to miRNA biogenesis.
Mlotshwa
Sizolwenkosi
S
Department of Biological Sciences, University of South Carolina, Columbia, South Carolina 29208, USA.
Schauer
Stephen E
SE
Smith
Trenton H
TH
Mallory
Allison C
AC
Herr
J M
JM
Roth
Braden
B
Merchant
Delwin S
DS
Ray
Animesh
A
Bowman
Lewis H
LH
Vance
Vicki B
VB
D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics*; D018797:Cell Cycle Proteins / Q000235:genetics*; D003546:Cysteine Endopeptidases / Q000235:genetics*; D018076:DNA, Complementary / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D020868:Gene Silencing / Q000502:physiology*; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D010942:Plant Viruses / Q000235:genetics*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D043244:Ribonuclease III / Q000235:genetics*; D015398:Signal Transduction / Q000235:genetics; D019076:Transgenes / Q000235:genetics; D014764:Viral Proteins / Q000235:genetics*
D029681:Arabidopsis Proteins; D018797:Cell Cycle Proteins; D018076:DNA, Complementary; D018744:DNA, Plant; D035683:MicroRNAs; D018749:RNA, Plant; D034741:RNA, Small Interfering; D014764:Viral Proteins; C402383:DCL1 protein, Arabidopsis; D043244:Ribonuclease III; D003546:Cysteine Endopeptidases; C072775:HC-Pro protein, potyvirus