Hypovirus papain-like protease p29 suppresses RNA silencing in the natural fungal host and in a heterologous plant system.
Virulence-attenuating hypoviruses of the species Cryphonectria hypovirus 1 (CHV1) encode a papain-like protease, p29, that shares similarities with the potyvirus-encoded suppressor of RNA silencing HC-Pro. We now report that hypovirus CHV1-EP713-encoded p29 can suppress RNA silencing in the natural host, the chestnut blight fungus Cryphonectria parasitica. Hairpin RNA-triggered silencing was suppressed in C. parasitica strains expressing p29, and transformation of a transgenic green fluorescent protein (GFP)-silenced strain with p29 resulted in an increased number of transformants with elevated GFP expression levels. The CHV1-EP713 p29 protein was also shown to suppress both virus-induced and agroinfiltration-induced RNA silencing and systemic spread of silencing in GFP-expressing transgenic Nicotiana benthamiana line 16c plants. The demonstration that a mycovirus encodes a suppressor of RNA silencing provides circumstantial evidence that RNA silencing in fungi may serve as an antiviral defense mechanism. The observation that a phylogenetically conserved protein of related plant and fungal viruses functions as a suppressor of RNA silencing in both fungi and plants indicates a level of conservation of the mechanisms underlying RNA silencing in these two groups of organisms.
Segers
Gerrit C
GC
Center for Biosystems Research, University of Maryland Biotechnology Institute, College Park, MD 20742-4450, USA.
van Wezel
Rene
R
Zhang
Xuemei
X
Hong
Yiguo
Y
Nuss
Donald L
DL
D001203:Ascomycota / Q000235:genetics* / Q000821:virology*; D009690:Nucleic Acid Conformation; D010447:Peptide Hydrolases / Q000378:metabolism*; D030821:Plants, Genetically Modified; D034622:RNA Interference; D012328:RNA Viruses / Q000201:enzymology*; D014026:Nicotiana / Q000235:genetics
D010447:Peptide Hydrolases