真菌病毒BcPV2导致灰葡萄孢毒力衰退的机制及生防潜力研究

Botrytis cinerea is a typical necrotrophic plant pathogenic fungus. It usually infects plants though floral organs, thus causing fruit rot. We can make a hypothesis that pre-treatment of flower petals with avirulent B. cinerea may suppress later colonization of the flower petals by virulent B. cinerea, thereby suppressing fruit infection by virulent B. cinerea. Our previous study identified an avirulent strain of B. cinerea, namely QT5-19. It was detected to have a novel partitivirus, Botrytis cinerea partitivirus 2 (BcPV2). The mycovirus was found to be transmissble among different strains of B. cinerea, suggesting that it might be a widely-spread mycovirus in B. cinerea. Strain QT5-19 was observed to be capable of suppressing infection and sporulation by virulent B. cinerea when it was inoculated simultaneuously with virulent B. cinerea on plant tissues, suggesting that both BcPV2 and QT5-19 have biocontrol potential. Thus, the present project was proposed to study the molecular mechanisms responsble for BcPV2-mediated pathogenicity debilitation in B. cinerea，to evaluate biocontrol efficacy of BcPV2 and QT5-19, and to disclose their modes of action in biological control. The content include transcriptional profiling of the genes in B. cinerea before and after infection by BcPV2, analysis of BcPV2-derived small RNAs and their gene targets in B. cinerea, determination of the horizontal transimission spectrum of BcPV2, deciphering of the mechanisms responsible for overcoming of the barier of hyphal imcompatibility between different strains of B. cinerea during BcPV2 transmission, and elucidation of the biocontrol mechanisms of BcPV2 and QT5-19 (saprophytic competition, BcPV2 transmission, induction of systemic resistance). The results will advance our understanding of the basic biology and application of BCPV2, and also broaden the theory and practice of biological control of plant gray mould disease.

灰葡萄孢（Botrytis cinerea, Bc）是死体营养型致病菌，常常籍植物花瓣侵入，引起果腐病。我们设想：用无毒Bc处理花瓣，它可能通过腐生竞争抑制强毒Bc定殖，进而减轻果腐病。本项目前期研究获得了无毒Bc菌株QT5-19，从中检测到一种新的双分体病毒BcPV2。BcPV2可在不同Bc菌株间发生水平传染，暗示BcPV2具广传染特性。当QT5-19与强毒Bc同时存在时，强毒Bc侵染和产孢能力受到明显抑制。因此，BcPV2及QT5-19具有生防潜力。鉴此，本项目提出研究BcPV2导致Bc毒力衰退的分子机制，评估BcPV2和QT5-19的生防效果，解析其生防机制。研究内容有：BcPV2侵染后Bc基因转录组分析、来源于BcPV2的小RNA分析、BcPV2水平传染谱测定及其突破菌丝不亲合障碍的机制解析、QT5-19生防效果测定及机制分析等。研究结果将丰富真菌病毒学和灰霉病生物防治理论与实践.

本项目旨在探讨灰葡萄孢菌株QT5-19致病力衰退的机制及其生物防治潜力。研究内容包括：解析QT5-19中真菌病毒BcPV2（Botrytis cinerea partitivirus 2）的分子特性及生物学特性；评估QT5-19的生防效果，并揭示生防机制；探讨BcPV2的与宿主互作的机制。结果表明：菌株QT5-19中存在BcPV2，该病毒属于分体病毒（Partitivirus）。QT5-19致病力衰退的机制包括：（1）侵染垫形成缺陷，丧失侵染能力；（2）细胞壁降解酶分泌能力下降，失去定殖能力。研究发现QT5-19对死体营养型病原真菌（灰葡萄孢、核盘菌）具有明显的防治效果，作用机制包括：（1）竞争作用，与强毒菌株相比，QT5-19的腐生竞争能力显著增强，抑制灰葡萄孢和核盘菌在衰老植物组织（如花瓣）上定殖以及随后对健康植物组织的侵染；（2）抗生作用，产生具有抗菌作用和促进植物生长双重活性的挥发性有机物，抑制病原真菌的侵染，提高植物免疫力。此外，研究发现：BcPV2产生的小RNA可上调与生物代谢及其代谢物跨膜转运等过程相关的基因表达，从而促进QT5-19产生挥发性物质。上述结果丰富了真菌病毒学和灰霉病生物防治的理论与实践。