核盘菌弱毒相关dsRNA的分析及其cDNA克隆

Sclerotinia sclerotiorum is a ubiquitous plant pathogenic fungus that can attack a wide range of plants, including many important crops. There is not any safe and efficient method to control Sclerotinia diseases. In our previously study, a transmissible hypovirulent strain Ep-1PN carried with three dsRNAsegments was isolated from diseased eggplant plant, and its potential for controlling Sclerotinia diseases was evaluated. We putated the dsRNA element in S. sclerotiorum is involved with the hypovirulence. The genetic stability of dsRNA in S. sclerotiorum was examined, and a dsRNAsegment with a size of 6.5kb was selected to make cDNA clone and sequencing analysis. RT-PCR result showed that the dsRNA would partially lost during its host domination, and totally lost during sexual production, as a result of that its sexual offspring was totally recovered from hypovirulence. The number of dsRNA segments is changed based on cultural conditions, however, a dsRNAsegment about 6.5kb was very stable correlated to the phenotype of strain Ep-1PN , and deduced to correspond to the hypovirulence. The 6.5kb dsRNA segment was recovered from low melting gel for cDNA cloning. Positive cDNA clones were subjected to sequencing analysis. Gaps between clones were bridged with RT-PCR. One large Open Reading Flame (ORF, with 1459 amino acid residues) was found out from the partial sequence of this dsRNA segment, and it was deduced to code a fusion protein with helicase 1 and RNA dependent RNA Polymerase(RdRp). Homology searching revealed that the putative protein is highly similar to those proteins coded by plant virus in Potexvirus. This is the first time we proved a hypovirulence associated mycovirus in S. sclerotiorum. The discovery of hypovirulence associated mycovirus in S. sclerotiorum are very important to study the original and evolution of mycovirus, the molecular interaction between mycovirus and its host, it also will be significant in Sclerotinia diseases control. Supported by this fund, we also discovered a mycovirus infecting Coniothyrium minitans, an important sclerotial parasite of S. sclerotiorum. As our knowledge, it is the first time we report a mycovirus in C. minitans.

核盘菌是重要的植物病原菌，常年造成巨大的经济损失。本项目拟分析弱素株