College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China.
National Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Biology and Germplasm Enhancement of Horticultural Crop (East China), Ministry of Agriculture and Rural Affairs, College of Horiticulture, Nanjing Agricultural University, Nanjing 210095, China.
Int J Mol Sci. 2022 Nov 24;23(23):14692. doi: 10.3390/ijms232314692.
A rhabditid entomopathogenic nematode (EPN), , has a stable symbiotic relationship with the bacterial strain S1 harbored in its intestines and drastically reduced viability when associated with a non-native strain (186) of the same bacterial species. This nematode is thus a good model for understanding the molecular mechanisms and interactions involved between a nematode host and a member of its intestinal microbiome. Transcriptome analysis and RNA-seq data indicated that expression levels of the majority (8797, 87.59%) of mRNAs in the non-native combination of and 186 were downregulated compared with the native combination, including strain S1. Accordingly, 88.84% of the total uniq-sRNAs mapped in the transcriptome were specific between the two combinations. Six DEGs, including two transcription factors ( and ) and four kinases (, , , and ), as well as an up-regulated micro-RNA, oc-miR-71, were found to demonstrate the regulatory mechanisms underlying diminished host viability induced by a non-native bacterial strain. and play key roles in the viability regulation of by positively mediating the expression of to indirectly impact its longevity and stress tolerances and by negatively regulating the expression of to affect the olfactory chemotaxis and fecundity. In response to the stress of invasion by the non-native strain, the expression of oc-miR-71 in the non-native combination was upregulated to downregulate the expression of its targeting oc, which might improve the localization and activation of the transcription factor DAF-16 in the nucleus to induce longevity extension and stress resistance enhancement to some extent. Our findings provide novel insight into comprehension of how nematodes deal with the stress of encountering novel potential bacterial symbionts at the physiological and molecular genetic levels and contribute to improved understanding of host-symbiont relationships generally.
一种小杆线虫昆虫病原线虫 (EPN) 与栖息在其肠道内的细菌菌株 S1 有着稳定的共生关系，而当与同一细菌物种的非本土菌株 (186) 相关联时，其生存能力会大幅降低。因此，这种线虫是研究线虫宿主与其肠道微生物群落成员之间涉及的分子机制和相互作用的良好模型。转录组分析和 RNA-seq 数据表明，与本土组合相比，非本土组合 和 186 中的大多数 (8797, 87.59%) mRNAs 的表达水平下调，包括菌株 S1。因此，在两个组合之间，有 88.84%的总 uniq-sRNAs 映射到 转录组中是特定的。发现六个差异表达基因 (DEGs)，包括两个转录因子 (和 ) 和四个激酶 (、、、和 )，以及一个上调的 micro-RNA，oc-miR-71，它们展示了由非本土菌株引起的宿主生存能力降低的调节机制。和 通过正向介导 的表达来间接影响其寿命和应激耐受性，以及通过负向调节 的表达来影响嗅觉趋化性和繁殖力，在非本土细菌菌株的生存力调节中发挥关键作用。为了应对非本土菌株入侵的压力，非本土组合中 oc-miR-71 的表达上调，以下调其靶向 oc 的表达，这可能会改善转录因子 DAF-16 在核内的定位和激活，从而在一定程度上诱导寿命延长和应激抗性增强。我们的研究结果为理解线虫如何在生理和分子遗传水平上应对遇到新的潜在细菌共生体的压力提供了新的见解，并有助于更好地理解宿主-共生体关系。
