Li Pengfei, Lin Yanhong, Zhang Hailong, Wang Shuangchao, Qiu Dewen, Guo Lihua
State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Science, Beijing, China.
State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Science, Beijing, China.
Virology. 2016 Feb;489:86-94. doi: 10.1016/j.virol.2015.12.004. Epub 2015 Dec 31.
We isolated a novel mycovirus, Fusarium graminearum mycotymovirus 1 (FgMTV1/SX64), which is related to members of the family Tymoviridae, from the plant pathogenic fungus F. graminearum strain SX64. The complete 7863 nucleotide sequence of FgMTV1/SX64, excluding the poly (A) tail, was determined. The genome of FgMTV1/SX64 is predicted to contain four open reading frames (ORFs). The largest ORF1 is 6723 nucleotides (nt) in length and encodes a putative polyprotein of 2242 amino acids (aa), which contains four conserved domains, a methyltransferase (Mtr), tymovirus endopeptidase (Pro), viral RNA helicase (Hel), and RNA-dependent RNA polymerase (RdRp), of the replication-associated proteins (RPs) of the positive-strand RNA viruses. ORFs 2-4 putatively encode three putative small hypothetical proteins, but their functions are still unknown. Sequence alignments and phylogenetic analyses based on the putative RP protein and the three conserved domains (Mtr, Hel and RdRp) showed that FgMTV1/SX64 is most closely related to, but distinctly branched from, the viruses from the family Tymoviridae. Although FgMTV1/SX64 infection caused mild or no effect on conidia production, biomass and virulence of its host F. graminearum strain SX64, its infection had significant effects on the growth rate, colony diameter and deoxynivalenol (DON) production. This is the first molecular characterization of a tymo-like mycovirus isolated from a plant pathogenic fungus. It is proposed that the mycovirus FgMTV1/SX64 is a representative member of new proposed lineage Mycotymovirus in the family Tymoviridae.
我们从植物病原真菌禾谷镰刀菌菌株SX64中分离出一种新型真菌病毒，即禾谷镰刀菌真菌 tymovirus 1（FgMTV1/SX64），它与番茄病毒科成员相关。测定了FgMTV1/SX64完整的7863个核苷酸序列（不包括聚腺苷酸尾）。预测FgMTV1/SX64的基因组包含四个开放阅读框（ORF）。最大的ORF1长度为6723个核苷酸（nt），编码一个推定的2242个氨基酸（aa）的多蛋白，该多蛋白包含四个保守结构域，即甲基转移酶（Mtr）、番茄病毒内肽酶（Pro）、病毒RNA解旋酶（Hel）和RNA依赖的RNA聚合酶（RdRp），它们是正链RNA病毒复制相关蛋白（RP）的组成部分。ORF 2 - 4推定编码三种推定的小假想蛋白，但其功能仍不清楚。基于推定的RP蛋白和三个保守结构域（Mtr、Hel和RdRp）的序列比对和系统发育分析表明，FgMTV1/SX64与番茄病毒科的病毒关系最为密切，但分支明显不同。虽然FgMTV1/SX64感染对其宿主禾谷镰刀菌菌株SX64的分生孢子产生、生物量和毒力造成轻微影响或无影响，但其感染对生长速率、菌落直径和脱氧雪腐镰刀菌烯醇（DON）产生有显著影响。这是从植物病原真菌中分离出的类番茄病毒真菌病毒的首次分子特征描述。有人提出真菌病毒FgMTV1/SX64是番茄病毒科新提出的谱系Mycotymovirus的代表性成员。
