Zhang Yue-Yang, Li Yan-Zhong, Shi Zun-Ji
State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, College of Pastoral Agriculture Science and Technology, Center for Grassland Microbiome, Engineering Research Center of Grassland Industry, Ministry of Education, Lanzhou University, Lanzhou 730020, China.
J Fungi (Basel). 2025 Jul 9;11(7):516. doi: 10.3390/jof11070516.
Plant-endophyte symbioses are widespread in grasslands. While symbiotic interactions often provide hosts with major fitness enhancements, the role of the endophyte , which produces swainsonine in locoweeds ( and spp.), remains enigmatic. We compared endophyte-infected (E+) and endophyte-free (E-) plants of three main Chinese locoweed species (, , and ) under controlled conditions, and analyzed environmental factors at locoweed poisoning hotspots for herbivores. The results demonstrated significant species-specific effects: E+ plants of and exhibited 26-39% reductions in biomass, net photosynthetic rate, and stomatal conductance, with elevated CO levels, while showed no measurable impacts. Swainsonine concentrations were 16-20 times higher in E+ plants (122.6-151.7 mg/kg) than in E- plants. Geospatial analysis revealed that poisoning hotspots for herbivores consistently occurred in regions with extreme winter conditions (minimum temperatures ≤ -17 °C and precipitation ≤ 1 mm during the driest month), suggesting context-dependent benefits under abiotic stress. These findings suggest that the ecological role of may vary depending on both host species and environmental context, highlighting a trade-off between growth costs and potential stress tolerance conferred by . The study underscores the need for field validation to elucidate the adaptive mechanisms maintaining this symbiosis in harsh environments.
植物与内生菌的共生关系在草原中广泛存在。虽然共生相互作用通常能极大地增强宿主的适应性，但内生菌（在疯草属植物（和 spp.）中产生苦马豆素）的作用仍然不明。我们在可控条件下比较了中国三种主要疯草属植物（、和）的内生菌感染植株（E+）和无内生菌植株（E-），并分析了食草动物疯草中毒热点地区的环境因素。结果显示出显著的物种特异性效应：和的E+植株的生物量、净光合速率和气孔导度降低了26%-39%，同时二氧化碳水平升高，而却未显示出可测量的影响。E+植株中的苦马豆素浓度（122.6-151.7毫克/千克）比E-植株高16-20倍。地理空间分析表明，食草动物中毒热点地区一直出现在冬季条件极端的地区（最冷月最低温度≤-17℃且降水量≤1毫米），这表明在非生物胁迫下存在依赖环境的益处。这些发现表明，的生态作用可能因宿主物种和环境背景而异，突出了生长成本与赋予的潜在胁迫耐受性之间的权衡。该研究强调需要进行实地验证，以阐明在恶劣环境中维持这种共生关系的适应性机制。
