Yan Siyuan, Zhang Qingchen, Jia Shuxin, Guo Miaomiao, Zhang Qiangqiang, Gu Peiwen
College of Forestry and Prataculture, Ningxia University, Yinchuan, China.
Department of Pharmacotherapy and Translational Research, University of Florida, Gainesville, FL, United States.
Front Microbiol. 2025 Jan 15;15:1487022. doi: 10.3389/fmicb.2024.1487022. eCollection 2024.
strain NQ8GII4 is an endophytic fungus with significant potential for improving growth and disease resistance of alfalfa. However, the molecular mechanisms underlying the symbiotic relationship between NQ8GII4 and alfalfa roots remain poorly understood.
In this study, we conducted (1) a comparative genomic analysis of selected saprophytic, pathogenic, and endophytic fungi, including molecular phylogeny analysis, whole-genome alignment, and divergence date estimation positioning, and (2) transcriptomic profiling of alfalfa roots infected with NQ8GII4.
Our findings reveal that NQ8GII4 is genetically closely related to , suggesting it diverged from phytopathogens. During the early stages of symbiosis establishment, genes encoding glycosyltransferases (GTs), fungal cell wall-degrading enzymes (FCWDEs), and steroid-14α-demethylase (CYP51) were significantly downregulated, potentially suppressing hyphal growth of the fungus. Once symbiosis was established, NQ8GII4 secreted effectors that activated plant immunity, which in turn could slow growth of the fungus. Moreover, genes involved in secondary metabolite biosynthesis, such as type I polyketide synthases (T1PKS) and non-ribosomal peptide synthetases (NRPSs), were significantly downregulated. Homologs of autophagy-related genes, including , and others, were also downregulated, suggesting that reduced phytotoxin production and autophagy inhibition is a consequence of NQ8GII4's symbiosis.
This study investigated the comprehensive molecular and genetic mechanisms governing the interaction between NQ8GII4 and alfalfa roots. Beyond the NQ8GII4-alfalfa system, these findings also provide a valuable molecular framework for understanding the mechanism of interactions between endophytic fungi and their host plants.
菌株NQ8GII4是一种内生真菌，在提高苜蓿生长和抗病性方面具有巨大潜力。然而，NQ8GII4与苜蓿根之间共生关系的分子机制仍知之甚少。
在本研究中，我们进行了以下两项实验：（1）对选定的腐生真菌、致病真菌和内生真菌进行比较基因组分析，包括分子系统发育分析、全基因组比对和分歧日期估计定位；（2）对感染NQ8GII4的苜蓿根进行转录组分析。
我们的研究结果表明，NQ8GII4在基因上与 密切相关，表明它与植物病原体发生了分化。在共生建立的早期阶段，编码糖基转移酶（GTs）、真菌细胞壁降解酶（FCWDEs）和类固醇-14α-脱甲基酶（CYP51）的基因显著下调，这可能抑制了真菌的菌丝生长。一旦共生建立，NQ8GII4分泌激活植物免疫的效应物，这反过来又可能减缓真菌的生长。此外，参与次生代谢物生物合成的基因，如I型聚酮合酶（T1PKS）和非核糖体肽合成酶（NRPSs），也显著下调。包括 等在内的自噬相关基因的同源物也下调，这表明植物毒素产生减少和自噬抑制是NQ8GII4共生的结果。
本研究调查了控制NQ8GII4与苜蓿根相互作用的全面分子和遗传机制。除了NQ8GII4-苜蓿系统外，这些发现还为理解内生真菌与其宿主植物之间的相互作用机制提供了有价值的分子框架。
