New research uncovers plant immune homeostasis mechanism

Research performed at The Sainsbury Laboratory in Norwich (UK) has helped us better understand how plants regulate their immune system.

Just like animals, plants have an immune system that helps them resist disease. Immune receptors embedded in plant cell membranes are able to detect molecular patterns of pathogens known as PAMPs. This triggers a cascade of reactions within the plant cell that leads to immunity. While this has been known for some time, it is not well understood how these immune responses are regulated.

Using the model plant species Arabidopsis thaliana and a newly developed genetic approach, the researchers showed that the protein kinase CPK28 is involved in the negative regulation of immunity. It works by regulating the protein levels of a key positive regulator of plant immunity, the kinase BIK1.

This research, ‘The calcium-dependent protein kinase CPK28 buffers plant immunity and regulates BIK1 turnover’, is published today in the journal Cell Host & Microbe. It was led by Professor Cyril Zipfel, Head of The Sainsbury Laboratory, who said: “Our work suggests that CPK28 constantly buffers the amplitude of immune signalling. Immune responses are costly and must therefore be tightly controlled to launch appropriate defence reactions against pathogens, without unnecessary energy consumption.”

Jacqueline Monaghan is a post-doctoral researcher in Professor Zipfel’s lab and first author on the paper. She said: “Our findings are interesting because they suggest that plant cells are able to fine-tune immune responses by simply regulating the turnover of a key enzyme involved in signalling. This knowledge could lead to a greater understanding of how to control plant immunity, for example in breeding new resistant crop varieties.”