作者机构：
[祝晓飞; 刘洪; 周倩] Hunan Provincial Universities Key Laboratory of Plant Disease Control and Utilization, College of Plant Protection, Hunan Agricultural University, Hunan, Changsha, 410128, China
通讯机构：
[Zhu, H.J.; Liu, F.] C;College of Plant Protection, China;College of Horticulture, China
关键词：
deep sequencing;mixed infections;mycoviruses;phomopsis blight of eggplant;Phomopsis vexans
摘要：
<jats:p><jats:italic>Phomopsis vexans</jats:italic>, which causes Phomopsis blight of eggplant, has been reported worldwide. To study the biocontrol of this disease, 162 leaf and fruit samples of eggplant Phomopsis blight were collected from Hunan, Hubei, Jiangxi, Sichuan, Zhejiang, Fujian, Guangdong and Anhui Provinces from 2017 to 2019. Eighty-seven pathogenic fungus isolates were identified as <jats:italic>P. vexans.</jats:italic> The following studies were conducted: screening of sporulation medium, spore morphology analysis, mycovirus detection and identification of novel mycoviruses in these isolates. The results showed that eggplant tissue medium was the most suitable medium for rapid sporulation, and all isolates had mycoviruses consisting of mainly mixed infections. The genome of these mycoviruses varied from 1-15 kb. Five novel mycoviruses infecting <jats:italic>P. vexans</jats:italic> were obtained, including “<jats:italic>Phomopsis vexans</jats:italic> fusarivirus 1” (PvFV1), “<jats:italic>Phomopsis vexans</jats:italic> ourmia-like virus 1” (PvOLV1), “<jats:italic>Phomopsis vexans</jats:italic> endornavirus 2” (PvEV2), “<jats:italic>Phomopsis vexans</jats:italic> partitivirus 1” (PvPV1) and “<jats:italic>Phomopsis vexans</jats:italic> victorivirus L1” (PvVVL1). Thus, PvVVL1 displays a unique genome structure, and this is the first report of a victorivirus consisting of two segments and of a deltapartitivirus infecting the fungus host.</jats:p>
摘要：
Mycovirus-infected fungi can suffer from poor growth, attenuated pigmentation, and virulence. However, the molecular mechanisms of how mycoviruses confer these symptoms remain poorly understood. Here, we report a mycovirus Stemphylium lycopersici alternavirus 1 (SlAV1) isolated from a necrotrophic plant pathogen Stemphylium lycopersici that causes altered colony pigmentation and hypovirulence by specifically interfering host biosynthesis of Altersolanol A, a polyketide phytotoxin. SlAV1 significantly down-regulates a fungal polyketide synthase (PKS1), the core enzyme of Altersolanol A biosynthesis. PKS1 deletion mutants do not accumulate Altersolanol A and lose pathogenicity to tomato and lettuce. Transgenic expression of SlAV1 open-reading frame 3 (ORF3) in S. lycopersici inhibits fungal PKS1 expression and Altersolanol A accumulation, leading to symptoms like SlAV1-infected fungal strains. Multiple plant species sprayed with mycelial suspension of S. lycopersici or S. vesicarium strains integrating and expressing ORF3 display enhanced resistance against virulent strains, converting the pathogenic fungi into biocontrol agents. Hence, our study not only proves inhibiting a key enzyme of host phytotoxin biosynthesis as a molecular mechanism underlying SlAV1-mediated hypovirulence of Stemphylium spp., but also demonstrates the potential of mycovirus-gene integrated fungi as a potential biocontrol agent to protect plants from fungal diseases.
摘要：
In this study, a novel mitovirus designed "Colletotrichum higginsianum mitovirus 1" (ChMV1) was isolated from the phytopathogenic fungus Colletotrichum higginsianum. The genome of this mitovirus is 2,893 nt in length with an A + U content of 61% and contains a large open reading frame (ORF) encoding an RNA-dependent RNA polymerase (RdRp). A BLASTp analysis revealed that the RdRp domain of ChMV1 had 30.25% to 61.72% sequence identity to those of members of the genus Mitovirus and showed the highest degree of similarity (61.72% identity) to Botrytis cinerea mitovirus 3 (BcMV3). Phylogenetic analysis further indicated that ChMV1 is a member in the genus Mitovirus of the family Mitoviridae. To the best of our knowledge, this is the first report of a mitovirus in C. higginsianum.
作者机构：
[Hui Wang; Hong Liu; Qian Zhou] Hunan Provincial Key Laboratory for Biology and Control of Plant Diseases and Insect Pests, Hunan Agricultural University, Changsha 410128, China;[Xun Lu] Agricultural Science Institute of XiangXi Tujia and Miao Autonomous Prefecture, 416000, China
通讯机构：
[Qian Zhou] H;Hunan Provincial Key Laboratory for Biology and Control of Plant Diseases and Insect Pests, Hunan Agricultural University, Changsha 410128, China
摘要：
A novel virus, Botryosphaeria dothidea bipartite mycovirus 1 (BdBMV1), was isolated from the plant-pathogenic fungus Botryosphaeria dothidea strain HNDT1, and the complete nucleotide sequence of its genome was determined. BdBMV1 consists of two genomic segments. The first segment is 1,976 bp in length and contains a single open reading frame (ORF) encoding the RNA-dependent RNA polymerase (RdRp) (68.95 kDa). The second segment is 1,786 bp in length and also contains a single ORF encoding a hypothetical protein of 35.19 kDa of unknown function. Based on the sequence of its RdRp, BdBMV1 is phylogenetically related to several other unclassified dsRNA mycoviruses, including Cryphonectria parasitica bipartite mycovirus 1 (CpBV1), and has a distant relationship to members of the family Partitiviridae.
摘要：
Here, a novel mycovirus, Botryosphaeria dothidea mitovirus 1 (BdMV1), was isolated from a phytopathogenic fungus, Botryosphaeria dothidea, and its molecular characteristics were determined. BdMV1 has a genome of 2,667 nt that contains a single large open reading frame (ORF) using the fungal mitochondrial genetic code. The ORF encodes an RNA-dependent RNA polymerase (RdRp) of 727 amino acids with a molecular mass of 81.64 kDa. BLASTp analysis revealed that the RdRp domain of BdMV1 has 39.59% and 39.18% sequence identity to Plasmopara viticola associated mitovirus 43 and Setosphaeria turcica mitovirus 1, respectively. Phylogenetic analysis further suggested that BdMV1 is a new member of the genus Mitovirus within the family Mitoviridae. To the best of our knowledge, this is the first report of a mitovirus in B. dothidea.
通讯机构：
[Qian Zhou] H;Hunan Provincial Key Laboratory for Biology and Control of Plant Diseases and Insect Pests, Hunan Agricultural University, Changsha, People’s Republic of China
