Ethylene Signaling Modulates Herbivore-Induced Defense Responses in the Model Legume Medicago truncatula
One or more effectors in the labial saliva (LS) of generalist Noctuid caterpillars activate plant signaling pathways to modulate jasmonate (JA)-dependent defense responses; however, the exact mechanisms involved have yet to be elucidated. A potential candidate in this phytohormone interplay is the e...
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| Format: | Article |
| Language: | English |
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The American Phytopathological Society
2015-05-01
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| Series: | Molecular Plant-Microbe Interactions |
| Online Access: | https://apsjournals.apsnet.org/doi/10.1094/MPMI-10-14-0348-R |
| _version_ | 1811291266254635008 |
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| author | Jamuna Risal Paudel Jacqueline C. Bede |
| author_facet | Jamuna Risal Paudel Jacqueline C. Bede |
| author_sort | Jamuna Risal Paudel |
| collection | DOAJ |
| description | One or more effectors in the labial saliva (LS) of generalist Noctuid caterpillars activate plant signaling pathways to modulate jasmonate (JA)-dependent defense responses; however, the exact mechanisms involved have yet to be elucidated. A potential candidate in this phytohormone interplay is the ethylene (ET) signaling pathway. We compared the biochemical and molecular responses of the model legume Medicago truncatula and the ET-insensitive skl mutant to herbivory by fourth instar Spodoptera exigua (Hübner) caterpillars with intact or impaired LS secretions. Cellular oxidative stress increases rapidly after herbivory, as evidenced by changes in oxidized-to-reduced ascorbate (ASC) and glutathione (GSH) ratios. The caterpillar-specific increase in GSH ratios and the LS-specific increase in ASC ratios are alleviated in the skl mutant, indicating that ET signaling is required. Ten hours postherbivory, markers of the JA and JA/ET pathways are differentially expressed; MtVSP is induced and MtHEL is repressed in a caterpillar LS- and ET-independent manner. In contrast, expression of the classic marker of the systemic acquired resistance pathway, MtPR1, is caterpillar LS-dependent and requires ET signaling. Caterpillar LS further suppresses the induction of JA-related trypsin inhibitor activity in an ET-dependent manner. Findings suggest that ET is involved in the caterpillar LS-dependent, salicylic acid/NPR1-mediated attenuation of JA-dependent induced responses. |
| first_indexed | 2024-04-13T04:26:51Z |
| format | Article |
| id | doaj.art-6cae0fe8d3cf433da25883b2c2fadac6 |
| institution | Directory Open Access Journal |
| issn | 0894-0282 1943-7706 |
| language | English |
| last_indexed | 2024-04-13T04:26:51Z |
| publishDate | 2015-05-01 |
| publisher | The American Phytopathological Society |
| record_format | Article |
| series | Molecular Plant-Microbe Interactions |
| spelling | doaj.art-6cae0fe8d3cf433da25883b2c2fadac62022-12-22T03:02:28ZengThe American Phytopathological SocietyMolecular Plant-Microbe Interactions0894-02821943-77062015-05-0128556957910.1094/MPMI-10-14-0348-REthylene Signaling Modulates Herbivore-Induced Defense Responses in the Model Legume Medicago truncatulaJamuna Risal Paudel0Jacqueline C. Bede1Department of Plant Science, McGill University, Ste-Anne-de-Bellevue, Qc, Canada, H9X 3V9, CanadaDepartment of Plant Science, McGill University, Ste-Anne-de-Bellevue, Qc, Canada, H9X 3V9, CanadaOne or more effectors in the labial saliva (LS) of generalist Noctuid caterpillars activate plant signaling pathways to modulate jasmonate (JA)-dependent defense responses; however, the exact mechanisms involved have yet to be elucidated. A potential candidate in this phytohormone interplay is the ethylene (ET) signaling pathway. We compared the biochemical and molecular responses of the model legume Medicago truncatula and the ET-insensitive skl mutant to herbivory by fourth instar Spodoptera exigua (Hübner) caterpillars with intact or impaired LS secretions. Cellular oxidative stress increases rapidly after herbivory, as evidenced by changes in oxidized-to-reduced ascorbate (ASC) and glutathione (GSH) ratios. The caterpillar-specific increase in GSH ratios and the LS-specific increase in ASC ratios are alleviated in the skl mutant, indicating that ET signaling is required. Ten hours postherbivory, markers of the JA and JA/ET pathways are differentially expressed; MtVSP is induced and MtHEL is repressed in a caterpillar LS- and ET-independent manner. In contrast, expression of the classic marker of the systemic acquired resistance pathway, MtPR1, is caterpillar LS-dependent and requires ET signaling. Caterpillar LS further suppresses the induction of JA-related trypsin inhibitor activity in an ET-dependent manner. Findings suggest that ET is involved in the caterpillar LS-dependent, salicylic acid/NPR1-mediated attenuation of JA-dependent induced responses.https://apsjournals.apsnet.org/doi/10.1094/MPMI-10-14-0348-R |
| spellingShingle | Jamuna Risal Paudel Jacqueline C. Bede Ethylene Signaling Modulates Herbivore-Induced Defense Responses in the Model Legume Medicago truncatula Molecular Plant-Microbe Interactions |
| title | Ethylene Signaling Modulates Herbivore-Induced Defense Responses in the Model Legume Medicago truncatula |
| title_full | Ethylene Signaling Modulates Herbivore-Induced Defense Responses in the Model Legume Medicago truncatula |
| title_fullStr | Ethylene Signaling Modulates Herbivore-Induced Defense Responses in the Model Legume Medicago truncatula |
| title_full_unstemmed | Ethylene Signaling Modulates Herbivore-Induced Defense Responses in the Model Legume Medicago truncatula |
| title_short | Ethylene Signaling Modulates Herbivore-Induced Defense Responses in the Model Legume Medicago truncatula |
| title_sort | ethylene signaling modulates herbivore induced defense responses in the model legume medicago truncatula |
| url | https://apsjournals.apsnet.org/doi/10.1094/MPMI-10-14-0348-R |
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