Two-layer response sensitisation and actuation establishes signal waves for systemic innate immunity

ABSTRACT: Intercellular and systemic signalling is an essential hallmark of multicellular life. Encounter of pathogens occurs locally but triggers organ scale and organismic immune responses. In plants, elicitor perception provokes rapid, systemically expanding Ca2+ and H2O2 second messenger signals conferring innate immunity. However, the underlying components and mechanisms for enabling and sustaining signal propagation have remained elusive. Here, we report how plants achieve perpetuated Ca2+/H2O2 signal proliferation and simultaneously avoid disturbance of ongoing cellular signalling along the path of response dissemination. We identify a CBL1/CIPK26/CPK5 Ca2+ sensing/phosphorylation module from Arabidopsis thaliana as crucial for systemic signal propagation. This bi-kinase signalling module becomes Ca2+-sensitized and super-activated through mutual trans-phosphorylation and in consequence imposes a cooperative and enhanced phosphorylation pattern on the RBOHD NADPH oxidase causing maximized H2O2 generation. Biochemical, genetic and Ca2+-biosensorics analyses reveal that RBOHD phosphorylation by both kinases is essential for elicitor triggered systemic Ca2+ signalling and innate immunity manifestation. Notably, combined CIPK26/CPK5 action dramatically lowers the Ca2+ concentration threshold of RBOHD activation, and phosphorylation of RBOHD Ser343/347 provides a complementary cis-acting substrate-sensitisation/activation mechanism through determining its Ca2+ binding efficiency. These dual signalling sensitisation and actuation mechanisms maximize signal proliferation at minimized Ca2+ signal intensity to obviate interference of long distance and cellular Ca2+ signalling.

ORGANISM(S): Homo Sapiens (human)

SUBMITTER: Iris Finkemeier 

PROVIDER: PXD038633 | JPOST Repository | Thu Nov 28 00:00:00 GMT 2024

REPOSITORIES: jPOST