Abiotic and biotic factors cause plant wounding and trigger complex short- and long-term responses at the local and systemic levels. These responses are under the control of complex signaling pathways, which are still poorly understood. Here, we show that the rapid activation of clade-A Mitogen Activated Protein Kinases (MAPKs) MPK3 and MPK6 by wounding depends on the upstream MAPK Kinases (MAP2Ks) MKK4 and MKK5 but is independent of jasmonic acid (JA) signaling. In addition, this fast module does not control wound-triggered JA accumulation in Arabidopsis, unlike its orthologues in tobacco. We also demonstrate that a second MAPK module, composed of MKK3 and the clade-C MAPKs MPK½/7, is activated by wounding in a MKK4/5-independent manner. We provide evidence that the activation of this MKK3-MPK½/7 module occurs mainly through wound-induced JA production via the transcriptional regulation of upstream clade-III MAP3Ks, particularly MAP3K14. We show that mkk3 mutant plants are more susceptible to herbivory from larvae of the generalist lepidopteran herbivore Spodoptera littoralis, indicating that the MKK3-MPK½/7 module is involved in counteracting insect feeding.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: We thank the Stress Signaling group for critical discussion of this work. We also thank Shuqun Zhang and Edward Farmer for providing mkk4 mkk5 and coi1-34 seeds. This work has benefited from a French State grant (LabEx Saclay Plant Sciences-SPS, ANR-10-LABX-0040-SPS), managed by the French National Research Agency under an "Investments for the Future"program (ANR-11-IDEX-0003-02). C.S. and C.C. were funded by SPS PhD fellowships. Marilia Almeida-Trapp gratefully acknowledges financial support by a Capes-Humboldt Research Fellowship. This publication has been written with the support of the AgreenSkills+fellowship program which has received funding from the EU’s Seventh Framework Program under grant agreement No. FP7-609398 (AgreenSkills+ contract) to STS