Anhui Provincial Key Laboratory of Microbial Pest Control, Anhui Agricultural University, Hefei, China.
Experimental Center of Clinical Research, The First Affliated Hospital of Anhui University of Chinese Medicine, Hefei, China.
Pest Manag Sci. 2021 Feb;77(2):1070-1080. doi: 10.1002/ps.6124. Epub 2020 Oct 22.
Entomopathogenic fungi have developed multiple strategies to overcome the immune defenses of their target insects, whereas insect pests have devised various defense mechanisms to combat fungal infection. However, differences in the molecular mechanisms of the innate immune defense strategies of insects upon infection with different fungal strains from the same species have not been reported.
Two Beauveria bassiana strains were obtained that significantly varied in their pathogenicity but were comparable in terms of growth, conidial yield, and cuticle penetration. To investigate the molecular mechanisms underlying the immune response of Plutella xylostella infected with these two strains, RNA-Seq was performed 48 h after infection. A total of 1027 differentially expressed genes (DEGs) were identified, and more than 200 DEGs were enriched in Kyoto Encyclopedia of Genes and Genome (KEGG) pathways involved in disease response, revealing differences in the immune response of P. xylostella to different B. bassiana infections at 48 h. Twenty-eight of the DEGs were related to innate immune functions, such as pathogen recognition, immune system activation and antimicrobial reactions. RNA interference (RNAi)-mediated gene silencing assays showed that PxApoLIII and PxCSP played critical roles in the P. xylostella immune response. PxApoLIII was expressed at higher levels during infection with the high-virulence strain, whereas PxCSP showed the opposite expression pattern during infection with the low-virulence strain, indicating that PxApoLIII and PxCSP might participate in P. xylostella innate immune defense against high- and low-virulence B. bassiana strains.
The present findings demonstrate that strains of a single species of pathogenic fungi that differ in virulence can induce the expression of different genes in P. xylostella. These results advance our knowledge of the molecular mechanisms underlying fungi-pest interactions.
昆虫病原真菌已经发展出多种策略来克服其靶昆虫的免疫防御，而昆虫害虫则设计了各种防御机制来对抗真菌感染。然而，同一物种的不同真菌菌株感染昆虫后，昆虫先天免疫防御策略的分子机制的差异尚未报道。
获得了两个致病力差异显著但在生长、分生孢子产量和表皮穿透方面相当的球孢白僵菌菌株。为了研究这两个菌株感染小菜蛾后免疫反应的分子机制，在感染后 48 小时进行了 RNA-Seq。共鉴定出 1027 个差异表达基因（DEGs），超过 200 个 DEGs 富集在参与疾病反应的京都基因与基因组百科全书（KEGG）途径中，表明小菜蛾对不同的球孢白僵菌感染的免疫反应在 48 小时时有差异。28 个 DEGs 与先天免疫功能有关，如病原体识别、免疫系统激活和抗菌反应。RNA 干扰（RNAi）介导的基因沉默试验表明，PxApoLIII 和 PxCSP 在小菜蛾免疫反应中发挥关键作用。在高毒力菌株感染期间，PxApoLIII 的表达水平较高，而在低毒力菌株感染期间，PxCSP 的表达模式相反，表明 PxApoLIII 和 PxCSP 可能参与了小菜蛾对高毒力和低毒力球孢白僵菌菌株的先天免疫防御。
本研究结果表明，毒力不同的单一病原真菌菌株可以诱导小菜蛾表达不同的基因。这些结果增进了我们对真菌-害虫相互作用分子机制的认识。
