淡紫拟青霉航天突变体对根结线虫作用的研究

Root-knot nematodes of the genus Meloidogyne are a kind of plant pathogens, which are widely-distributed and difficult to control and do great harm in the world's agricultural plants. At present, Paecilomyces lilacinus is believed to be one of important biocontrol agents for controlling root-knot nematodes. By boarding on Shenzhou-8 spacecraft, the P.lilacinus mutant strains were obtained with the phenotype changed. Through the biological research of the mutant strains, the mutant strains were screened for sporulation changes and pathogenicity changes to the root-knot nematodes.Comparative analysis was carried out through the transcriptomics profiling of the mutant strains and the wild strains.The transcriptomics method is used to find differential expression genes, the genes and expressed proteins are studied from the aspects of functional classification, cellular localization and metabolic pathways, and reasons for biological change of the mutant strains are explained from the perspective of genome. All these studies will lay down a solid foundation to further promote identification of nematocidal virulence genes of this fungus , and to explain the molecular mechanism which triggers the mutation, determine the nematode-fungus molecule interaction mechanism, and to explain the reaction between P. lilacinus and plant parasitic nematodes as well as improvement of application efficiency of P.lilacinus. Therefore, this study will be significance in theory and practice.

根结线虫是一类对世界农业生产危害十分严重且分布广、难以防治的植物病原物，目前认为淡紫拟青霉是根结线虫病的重要生防制剂之一。淡紫拟青霉菌株通过神舟八号飞船搭载后，获得淡紫拟青霉表型改变的突变体菌株。通过对突变体菌株生物学研究，筛选对根结线虫的致病力改变或产孢改变的菌株，通过对突变菌株与野生菌株的转录组学表达谱比较分析，使用组学的方法寻找差异表达基因，从功能分类、细胞定位和代谢通路等方面对基因和表达的蛋白进行研究，从基因组的层面解释突变菌株生物学变化的原因。这些研究将为进一步推动真菌杀线虫毒力基因鉴定、阐明引发诱变的分子机制，明确线虫-真菌分子互作机理、解释淡紫拟青霉与植物寄生线虫作用过程，同时为生产上培育高效生防菌株打下良好基础，因此该项研究在理论上和实践上都具有重要意义。

利用淡紫拟青霉山东菌株搭载“神舟八号”宇宙飞船进行诱变处理。对筛选得到的30个淡紫拟青霉航天诱变菌株进行了形态、色素、菌丝及孢子形态、菌落生长速度、菌丝干重和产孢量等生物学检测，同时研究了各航天诱变菌株对松材线虫和南方根结线虫的致病力及与致病力相关酶—几丁质酶的变化。结果表明：淡紫拟青霉航天突变菌株各项生物学特性与原始菌株存在分化。航天诱变后的菌株菌落形态、色素和菌丝结构与原始菌株差异明显；菌落生长速度、菌丝干重和产孢量的负突变率均高于正突变率；突变菌株Sd-m-9、Sd-m-11、Sd-m-16、Sd-m-22和Sd-m-26的几丁质酶活力和蛋白酶活力显著提高，与航天突变菌株对线虫的致病力相关，可以生防菌株的标准之一。.突变菌株对不同的靶标松材线虫和南方根结线虫的作用存在不同。突变菌株对靶标松材线虫卵的寄生率较低，寄生率最高的菌株Sd-m-20的寄生率仅为18.0%,寄生率正变异率最高为54.24%，负变异率最高为-14.31%；突变体菌株Sd-m-28发酵液对松材线虫的致病力最高为20%，说明突变体菌株对松材线虫也有一定的寄生能力。.突变菌株对根结线虫卵致病力较高，菌株 Sd-m-9，Sd-m-11，Sd-m-16，和Sd-m-26对根结线虫卵的寄生率分别提高了14.48%、14.90%、12.35%和17.45%，其中寄生率最高的菌株为Sd-m-26，寄生率为92.00%，显著高于原始菌株的寄生率（78.3%）。突变体菌株发酵液在12小时对根结线虫二龄幼虫的死亡率力达到100%。航天诱变处理对淡紫拟青霉影响显著，其诱变后的优良菌株可能用于淡紫拟青霉对南方根结线虫的生物防治。