|YU, LIN - Huazhong Agricultural University|
|SANG, WEN - Huazhong Agricultural University|
|WU, MINGDE - Huazhong Agricultural University|
|ZHANG, JING - Huazhong Agricultural University|
|YANG, LONG - Huazhong Agricultural University|
|ZHOU, YING-JUN - Huazhong Agricultural University|
|LI, GUOQING - Huazhong Agricultural University|
Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2015
Publication Date: 4/1/2015
Citation: Yu, L., Sang, W., Wu, M., Zhang, J., Yang, L., Zhou, Y., Chen, W., Li, G. 2015. Novel hypovirulence-associated RNA mycovirus in the plant pathogenic fungus botrytis cinerea: molecular and biological characterization. Applied and Environmental Microbiology. 81:2299-2310.
Interpretive Summary: Botrytis cinerea is an important plant pathogen causing gray mold on many economically important crops and ornamental plants. It is a fungal species related to Sclerotinia sclerotiorum. Managing gray mold is difficult and requires applications of fungicides at timely manner, and resistance is inadequate in many crops. Developing biological control would be an alterative and could be a component of an integrated management package. Mycoviruses are viruses that infect fungi and could have debilitating effect on the host fungi. Just like Sclerotinia sclerotiorum, Botrytis cinerea harbors many mycoviruses, and this research was carried out to explore mycoviruses for managing Bottrytis gray mold. A novel RNA mycovirus named Botrytis cinerea RNA virus 1 (BcRV1) found in Botrytis cinerea was biologically and molecularly characterized. Mycovirus BcRV1 has a genome size of 8,952 bp with two putative overlapping open reading frames (ORFs) coding for a hypothetical polypeptide (P1) and RNA-dependent RNA polymerase (RdRp), respectively. BcRV1 belongs to a taxonomically unassigned dsRNA mycovirus group. It is closely related to Grapevine-associated totivirus 2 and Sclerotinia sclerotiorum nonsegmented virus L. BcRV1 can be transmitted vertically through macroconidia and horizontally to other B. cinerea strains through hyphal contact. This mycovirus is closely associated with hypovirulence of Botrytis cinerea, and could be explored as biocontrol agent against Botrytis gray mold.
Technical Abstract: Botrytis cinerea is a pathogenic fungus causing gray mold disease on numerous economically important crops and ornamental plants. This study was conducted to characterize the biological and molecular features of a novel RNA mycovirus, Botrytis cinerea RNA virus 1 (BcRV1), in the hypovirulent strain BerBc-1 of B. cinerea. The genome of BcRV1 is 8,952 bp long with two putative overlapped open reading frames (ORFs), ORF1 and ORF2, coding for a hypothetical polypeptide (P1) and RNA-dependent RNA polymerase (RdRp), respectively. A -1 frameshifting region (designated as the KNOT element), including a shifty heptamer, a heptanucleotide spacer and an H-type pseudoknot, was predicted in the junction region of ORF1 and ORF2. There may exist a -1 frameshifting in BcRV1 for production of the fusion polypeptide P1-RdRp. The -1 frameshifting role of the KNOT element was experimentally confirmed through determining production of the fusion protein RFP-GFP by the plasmid containing the construct dsRed-KNOT-eGFP in Escherichia coli. BcRV1 belongs to a taxonomically unassigned dsRNA mycovirus group. It is closely related to Grapevine-associated totivirus 2 and Sclerotinia sclerotiorum nonsegmented virus L. BcRV1 in strain BerBc-1 was capable of being transmitted vertically through macroconidia and horizontally to other B. cinerea strains through hyphal contact. It was found to be closely associated with hypovirulence of B. cinerea. The attenuation effect of BcRV1 on mycelial growth and pathogenicity of B. cinerea was greatly affected by the viral accumulation level. This study presentes a novel mycoviral mechanism associated with hypovirulence of B. cinerea.