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Stratmann, J. W.

Publications and source records attributed to Stratmann, J. W..

2 recordsLinked to original sources
bioRxiv2022

Green leaf volatiles co-opt proteins involved in molecular pattern signaling in plant cells

The green leaf volatiles (GLVs) Z-3-hexen-1-ol and Z-3-hexenyl acetate are airborne infochemicals released from damaged plant tissues that prime defenses against herbivores and pathogens in receiver plants. They are conceptually similar to well-known damage-associated molecular patterns (DAMPs), but little is known about their mechanism of action. Using tomato cell cultures, we found that rapid responses to the two GLVs and the polypeptide DAMP systemin showed a significant overlap but also GLV-specific patterns. Within five minutes, GLVs induced changes in MAPK activity and proton-fluxes as well as rapid and massive changes in the phosphorylation status of proteins. Many of these proteins are involved in reprogramming the proteome from cellular homeostasis to stress and include pattern recognition receptors, a receptor-like cytoplasmic kinase, MAPK cascade components, calcium signaling proteins, and transcriptional regulators, all of which are also components of DAMP signaling pathways. This phosphoproteome may represent an early priming state that enables plants to respond forcefully to a subsequent stress signal.

plant biology↗
bioRxiv2022

A complete MAPK cascade, a calmodulin, and a protein phosphatase act downstream of CRK receptor kinases and regulate Arabidopsis innate immunity

Mitogen-activated protein kinase (MAPK) cascades are critical signal transduction modules in stress responses, but how their composition and mode of activation induces a stress response is poorly understood. We showed in Arabidopsis that CRK21, a cysteine-rich receptor-like protein kinase (CRK), phosphorylates MAPK kinase kinase 20 (MKKK20) and thus directly activates a novel MAPK cascade, consisting of MKKK20, the MAPK kinase MKK3, and the MAPK MPK6. Furthermore, the protein phosphatase PP2C76 and the calmodulin CaM7 were identified as negative and positive modulators of the cascade, respectively. Loss-of-function in components of the MAPK cascade or in CaM7 led to susceptibility to the bacterial pathogen Pseudomonas syringae and the fungal pathogen Botrytis cinerea. In contrast, loss-of-function of PP2C76 as well as transient overexpression of the genes in the MAPK cascade and CaM7 conferred resistance to the pathogens. Moreover, seven additional CRKs interacted with MKKK20 in vivo, and four of these were highly expressed after inoculation with P. syringae. In summary, our findings demonstrate that the novel CRK21-MKKK20-MKK3-MPK6 signaling pathway functions in immunity to fungal and bacterial pathogens and that CRKs may function in directly activating MKKKs.

plant biology↗