Developmental Defects Mediated by the P1/HC-Pro Potyviral Silencing Suppressor Are Not Due to Misregulation of AUXIN RESPONSE FACTOR 8.
Plant viral suppressors of RNA silencing induce developmental defects similar to those caused by mutations in genes involved in the microRNA pathway. A recent report has attributed viral suppressor-mediated developmental defects to up-regulation of AUXIN RESPONSE FACTOR 8 (ARF8), a target of miR167. The key piece of evidence was that the developmental defects in transgenic Arabidopsis (Arabidopsis thaliana) expressing viral suppressors were greatly alleviated in the F1 progeny of a cross with plants carrying the arf8-6 mutation. Arf8-6 is a SALK line T-DNA insertion mutant, a class of mutations prone to inducing transcriptional silencing of transgenes expressed from the 35S promoter. We have reinvestigated the role of ARF8 in viral suppressor-mediated developmental defects, using two independent arf8 mutations and the P1/HC-Pro potyviral suppressor of silencing. Progeny of a cross between P1/HC-Pro transgenic Arabidopsis and the arf8-6 T-DNA insertion mutant showed little effect on the P1/HC-Pro phenotype in the F1 generation, but almost all arf8-6/P1/HC-Pro progeny had lost the phenotype in the F2 generation. However, the loss of phenotype in the F2 generation was not correlated with the number of functional copies of the ARF8 gene. Instead, it reflected transcriptional silencing of the P1/HC-Pro transgene, as evidenced by a pronounced decrease in P1/HC-Pro mRNA and the appearance of 35S promoter small interfering RNAs. Furthermore, an independent loss-of-function point mutation, Arf8-8, had no detectable effects on P1/HC-Pro phenotype in either the F1 or F2 generations. Together, these data argue against the previously reported role of increased ARF8 expression in developmental defects caused by P1/HC-Pro.
Department of Biological Sciences, University of South Carolina, Columbia, South Carolina 29208 (S.M., G.J.P., J.L.M., V.V.); and.|Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599 (J.W.R.).
Sizolwenkosi
0000-0002-2973-2489
S
Mlotshwa
Department of Biological Sciences, University of South Carolina, Columbia, South Carolina 29208 (S.M., G.J.P., J.L.M., V.V.); and.|Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599 (J.W.R.).
Gail J
GJ
Pruss
Department of Biological Sciences, University of South Carolina, Columbia, South Carolina 29208 (S.M., G.J.P., J.L.M., V.V.); and.|Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599 (J.W.R.).
John L
JL
MacArthur
Department of Biological Sciences, University of South Carolina, Columbia, South Carolina 29208 (S.M., G.J.P., J.L.M., V.V.); and.|Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599 (J.W.R.).
Jason W
0000-0001-7508-9714
JW
Reed
Department of Biological Sciences, University of South Carolina, Columbia, South Carolina 29208 (S.M., G.J.P., J.L.M., V.V.); and vance@biol.sc.edu.|Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599 (J.W.R.) vance@biol.sc.edu.
Vicki
V
Vance
D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000821:virology*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D003433:Crosses, Genetic; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D016153:Genes, Suppressor; D016254:Mutagenesis, Insertional / Q000235:genetics; D010641:Phenotype; D017354:Point Mutation / Q000235:genetics; D017800:Potyvirus / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D034622:RNA Interference; D014764:Viral Proteins / Q000378:metabolism*
D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; C036483:T-DNA; D014764:Viral Proteins; C495666:auxin response factor 8, Arabidopsis; D003546:Cysteine Endopeptidases; C072775:HC-Pro protein, potyvirus
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