Host-Specific and Environment-Dependent Effects of Endophyte <i>Alternaria oxytropis</i> on Three Locoweed <i>Oxytropis</i> Species in China
Plant–endophyte symbioses are widespread in grasslands. While symbiotic interactions often provide hosts with major fitness enhancements, the role of the endophyte <i>Alternaria oxytropis</i>, which produces swainsonine in locoweeds (<i>Oxytropis</i> and <i>Astragalus&l...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-07-01
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| Series: | Journal of Fungi |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2309-608X/11/7/516 |
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| Summary: | Plant–endophyte symbioses are widespread in grasslands. While symbiotic interactions often provide hosts with major fitness enhancements, the role of the endophyte <i>Alternaria oxytropis</i>, which produces swainsonine in locoweeds (<i>Oxytropis</i> and <i>Astragalus</i> spp.), remains enigmatic. We compared endophyte-infected (E+) and endophyte-free (E−) plants of three main Chinese locoweed species (<i>O. kansuensis</i>, <i>O. glabra</i>, and <i>O. ochrocephala</i>) under controlled conditions, and analyzed environmental factors at locoweed poisoning hotspots for herbivores. The results demonstrated significant species-specific effects: E+ plants of <i>O. glabra</i> and <i>O. ochrocephala</i> exhibited 26–39% reductions in biomass, net photosynthetic rate, and stomatal conductance, with elevated CO<sub>2</sub> levels, while <i>O. kansuensis</i> 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 <i>A. oxytropis</i> may vary depending on both host species and environmental context, highlighting a trade-off between growth costs and potential stress tolerance conferred by <i>A. oxytropis</i>. The study underscores the need for field validation to elucidate the adaptive mechanisms maintaining this symbiosis in harsh environments. |
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| ISSN: | 2309-608X |