Ca 2+ signaling by plant Arabidopsis thaliana Pep peptides depends on AtPepR1, a receptor with guanylyl cyclase activity, and cGMP-activated Ca 2+ channels

Abstract
A family of peptide signaling molecules (AtPeps) and their plasma membrane receptor AtPepR1 are known to act in pathogendefense signaling cascades in plants. Little is currently known about the molecular mechanisms that link these signaling peptides and their receptor, a leucine-rich repeat receptor-like kinase, to downstream pathogen-defense responses. We identify some cellular activities of these molecules that provide the context for a model for their action in signaling cascades. AtPeps activate plasma membrane inwardly conducting Ca 2+ permeable channels in mesophyll cells, resulting in cytosolic Ca 2+ elevation. This activity is dependent on their receptor as well as a cyclic nucleotide-gated channel (CNGC2). We also show that the leucine-rich repeat receptor- like kinase receptor AtPepR1 has guanylyl cyclase activity, generating cGMP from GTP, and that cGMP can activate CNGC2- dependent cytosolic Ca 2+ elevation. AtPep-dependent expression of pathogen-defense genes (PDF1.2, MPK3, and WRKY33) is mediated by the Ca 2+ signaling pathway associated with AtPep peptides and their receptor. The work presented here indicates that extracellular AtPeps, which can act as danger-associated molecular patterns, signal by interaction with their receptor, AtPepR1, a plasma membrane protein that can generate cGMP. Downstream from AtPep and AtPepR1 in a signaling cascade, the cGMP-activated channel CNGC2 is involved in AtPep- and AtPepR1-dependent inward Ca 2+ conductance and resulting cytosolic Ca 2+ elevation. The signaling cascade initiated by AtPeps leads to expression of pathogen- defense genes in a Ca 2+-dependent manner.

Citation
Qi, Z., Verma, R., Gehring, C., Yamaguchi, Y., Zhao, Y., Ryan, C. A., & Berkowitz, G. A. (2010). Ca2+ signaling by plant Arabidopsis thaliana Pep peptides depends on AtPepR1, a receptor with guanylyl cyclase activity, and cGMP-activated Ca2+ channels. Proceedings of the National Academy of Sciences, 107(49), 21193–21198. doi:10.1073/pnas.1000191107

Acknowledgements
We thank Dr. Kiyoshi Masuda (Hokkaido University, Sapporo, Japan) for use of the real-time quantitative PCR machine, Dr. Gregory Pearce (Washington State University, Pullman, WA) for generating AtPep peptides, and Dr. Wei-Hua Wu (China Agriculture University, Beijing, China) for use of patch clamp equipment for some experiments. This work was supported by National Science Foundation Award 0844715 (to G. A. B.). Some work by Z.Q. was supported by a Program of Higher-Level Talents of Inner Mongolia University award (to Z.Q.).

Publisher
Proceedings of the National Academy of Sciences

Journal
Proceedings of the National Academy of Sciences

DOI
10.1073/pnas.1000191107

PubMed ID
21088220

PubMed Central ID
PMC3000296

Additional Links
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3000296

Permanent link to this record