叶面真菌群落对白粉病发病的分子生态响应机制

Response in Fungal Community on Plant Leaves to Powdery Mildew

叶面微生物群落组成与植物叶部病害发生密切相关,但植物真菌性叶部病害的发病程度与叶面真菌群落组成及多样性的关联机制仍然未知。本研究利用真核生物内源转录间隔区(ITS)扩增子高通量测序技术,在茄科作物白粉病不同发病程度下,研究了叶面真菌群落的组成和多样性差异,解析了叶面真菌分子生态网络拓扑性质的变化规律,并探明了叶面真菌群落系统发育装配的生态过程。多样性分析表明,随着白粉病病情程度加重,叶面真菌群落丰富度及多样性逐渐下降;网络分析表明,相较于中度和重度感病植株,轻微发病植株叶面真菌网络的节点和连接数更多,网络密度、聚集系数和平均连通度更高。在不同发病程度的植株中,叶面真菌群落的系统发育装配的生态过程均由随机性主导,但随着发病程度加重,叶面真菌群落趋向于系统发育扩散。综上所述,病原菌入侵改变了叶面真菌群落结构,扰动了真菌群落之间的相互作用和群落系统发育的生态装配过程,这些结果为深入认识白粉病病害与叶面真菌群落关联机制和生产上防控该病具有重要意义。

The composition of microbial communities on leaf surface is closely related to plant foliar diseases.However,the response in fungal community on plant leaves to the severity of pant diseases are still unknown.In this study,we used highthroughput ITS amplicon sequencing technology to investigate the differences in the composition and diversity of fungal community on plant leaves with different disease severities of powdery mildew disease in Solanaceae crops.We analyzed the changes in the topological properties of molecular ecological networks of fungal community and explored the ecological processes of community phylogenetic assembly.Diversity analysis showed that as the severity of powdery mildew disease increased,the richness and diversity of fungal communities gradually decreased.Network analysis revealed that compared to plants with moderate and severe infection,plants with mild disease symptoms had more nodes and connections in the ecological network,with higher network density,clustering coefficient,and average connectivity.Among the plants with different disease severities,the ecological processes of phylogenetic assembly in fungal communities were dominated by stochastic processes,whereas the fungal communities tended to have phylogenetic dispersion with increasing severity of powdery mildew.In conclusion,invasive pathogens alter the existing community structure,disrupt the interactions between fungal communities,and influence the ecological processes of community phylogenetic assembly.These findings provide a deep insight into the association between powdery mildew disease and the fungal community on plant leaves.