外生菌根真菌提高油松抗松萎蔫病机制研究

Pine wilt disease, caused by pinewood nematode (Bursaphelenchus xylophilus), is threating the forest resources and ecological environment in our country. It is very urgent to find effective method to control pine wilt disease. Ectomycorrhizal fungi(ECMF)are known can increase the resistence of host plant to the pathogen. Some reports have showed that ECMF can influence the happeness and damage of pine wilt disease. Further studies are required to prove the influence degree and the related machenism. The applicant intends to (1) comprehensively analysis the influence of ECMF on pine wilt disease through studies on the variety in colonization rate, community structure and diversity of ECMF between the heavy and light infection areas, and the influence of ECMF strains on the proliferation of pinewood nematode, the growth of pine seedlings, as well as the virulence of pine wilt disease; (2) reveal the mechanism of ECMF strains inducing resistance in pine seedlings against pine wilt disease through researches on the histological and physiological characteristics, the content of defense-related metabolites, the activity of defense-related proteases, and the expression levels of defense-related genes in infected pine seedling caused by pinewood nematode; (3) evaluate the feasibility of applying ECMF to control pie wilt disease. Completion of the project is helpful to search the suitable biotic factors which can inhence the resistance of pine tree against pine wilt disease, and provides the theroy foundation and new direction for the biocontrol of pine wilt disease.

由松材线虫引起的松萎蔫病已严重威胁我国森林资源和生态环境，阻碍我国林业生态文明建设发展,防控已刻不容缓。外生菌根真菌（ECMF）能增强宿主抗病性，但对松萎蔫病影响的程度和作用机理尚不清楚。 本研究旨在通过研究松萎蔫病不同危害程度林分中ECMF侵染程度、群落结构和多样性的差异，以及ECMF菌株对松材线虫种群增殖、油松生长和松萎蔫病致病力的影响， 全面分析和评估ECMF对松萎蔫病的影响；并通过研究ECMF菌株对感病苗木的组织结构和生理活性、抗病相关代谢物质含量和抗病相关蛋白酶活性，以及抗病相关基因EST表达量的影响，揭示ECMF菌株提高油松对松萎蔫病抗性的生理生化和分子机制，评估利用ECMF防控松萎蔫病的可行性。 项目的完成有助于探索提高松树抗松萎蔫病的生物因子和方法，为松萎蔫病生物防治提供理论基础和新思路。

由松材线虫引起的松萎蔫病严重威胁我国森林资源和生态环境，防控已刻不容缓。外生菌根真菌（ECMF）和深色有隔内生真菌（DSE）能增强宿主植物抗病性，但对松萎蔫病的影响和相关机制尚不明确。本项目研究了松萎蔫病不同危害程度林分中油松根部ECMF和DSE的侵染率、根相关真菌（RAF，包括ECMF、DSE和其他根部真菌）的种群结构和多样性、根际土壤理化性质和土壤酶活性、根际土壤微生物的群落结构和多样性等，阐明了松萎蔫病的发生和危害程度对油松根部菌根真菌侵染率、RAF和根际土壤微生物群落结构、土壤理化性质等的影响。结果表明，松萎蔫病能够改变油松根部RAF和根际土壤微生物的群落结构和多样性，影响土壤理化性质；油松根部ECMF侵染率显著高于DSE，松萎蔫病的危害程度与ECMF侵染率、油松根际土菌丝密度、土壤pH值和全磷呈显著负相关，而与DSE侵染率、土壤蔗糖酶活性，以及土壤全氮、硝态氮、有机质含量呈显著正相关。从油松根尖和大型真菌子实体中分离培养了87种ECMF和DSE，通过研究它们对松材线虫种群增殖、油松生长和松萎蔫病致病力的影响，初步筛选出能显著提高油松松萎蔫病抗性的2个ECMF和2个DSE菌株，接种后可在一定程度上延缓松萎蔫病的发病时间和死亡时间，降低松树死亡率；通过研究接菌后油松体内抗病相关蛋白酶活性和抗病相关物质含量，以及油松根际土壤理化性质、根部和根际土壤微生物群落的变化，揭示了ECMF和DSE提高油松抗松萎蔫病的相关机制。结果表明，ECMF和DSE能通过激发油松的抗病系统，调节油松体内的抗病相关酶活性和抗病相关物质的含量，减轻由PWN入侵而导致的油松过激“免疫” 反应，调节RAF和根际土壤微生物的群落结构，改善油松根际微环境，从而提高了油松对松萎蔫病的抗性。总之，ECMF和DSE菌株可提高油松对松萎蔫病的抗性，降低松萎蔫病的危害程度，可用于松萎蔫病的生物防治。项目的完成可为松萎蔫病的前期诊断提供依据，有助于探索提高松树抗松萎蔫病的生物因子和方法，为松萎蔫病生物防治提供理论基础和新思路。