Epiphytic Fungi Can Drive a Trade-Off Between Pathogen and Herbivore Resistance in Invasive <i>Ipomoea cairica</i>
Trade-offs between different defense traits exist commonly in plants. However, no evidence suggests that symbiotic microbes can drive a trade-off between plant pathogen and herbivore defense. The present study aims to investigate whether the mixture of epiphytic <i>Fusarium oxysporum</i>...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2024-10-01
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| Series: | Microorganisms |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2076-2607/12/11/2130 |
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| Summary: | Trade-offs between different defense traits exist commonly in plants. However, no evidence suggests that symbiotic microbes can drive a trade-off between plant pathogen and herbivore defense. The present study aims to investigate whether the mixture of epiphytic <i>Fusarium oxysporum</i> and <i>Fusarium fujikuroi</i> can drive the trade-off between the two defense traits in invasive <i>Ipomoea cairica</i>. Surface-sterilized <i>I. cairica</i> cuttings pre-inoculated with the epiphytic fungal mixture served as an epiphyte-inoculated (E+) group, while cuttings sprayed with sterile PDB served as an epiphyte-free (E−) group. After 3 days of incubation, E+ and E− cuttings were subjected to the challenge from a fungal pathogen and an insect herbivore, respectively. The results suggested that E+ cuttings had less rotted and yellowed leaf rates per plant than E− cuttings after <i>Colletotrichum gloeosporioides</i> infection. On the contrary, E+ cuttings had higher absolute and relative fresh weight losses per leaf than E− cuttings after <i>Taiwania circumdata</i> introduction. In the absence of challenges from the two natural enemies, salicylic acid and H<sub>2</sub>O<sub>2</sub> accumulation occurred in E+ cuttings, which activated their SA-dependent pathogen defense and resulted in an increase in chitinase and β-1,3-glucanase activities. Although jasmonic acid accumulation also occurred in E+ cuttings, their JA-dependent herbivore defense responses were antagonized by SA signaling, leading to a decrease in total phenol content and phenylalanine ammonia-lyase activity. The activity of generalized defense enzymes, including superoxide dismutase, peroxidase, and catalase, did not differ between E+ and E− cuttings. Together, our findings indicate that a trade-off between pathogen and herbivore defense in <i>I. cairica</i> had already been driven by the epiphytic fungal mixture before the challenge by the two natural enemies. This study provides a novel insight into biocontrol strategies for <i>I. cairica</i>. |
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| ISSN: | 2076-2607 |