Work

PP2C phosphatase Pic14 negatively regulates tomato Pto/Prf‐triggered immunity by inhibiting MAPK activation

Year: 2024

Type: article

Abstract: SUMMARY Type 2C protein phosphatases (PP2Cs) are emerging as important regulators of plant immune responses, although little is known about how they might impact nucleotide-binding, leucine-rich repeat (NLR)-triggered immunity (NTI). We discovered that expression of the PP2C-immunity associated candidate 14 gene ( Pic14 ) is induced upon activation of the Pto/Prf-mediated NTI response in tomato. Pto/Prf recognize the effector AvrPto translocated into plant cells by the pathogen Pseudomonas syringae pv. tomato ( Pst ) and activate a MAPK cascade and other responses which together confer resistance to bacterial speck disease. Pic14 encodes a PP2C with an N-terminal kinase-interacting motif (KIM) and a C-terminal phosphatase domain. Upon inoculation with Pst -AvrPto, Pto/Prf-expressing tomato plants with loss-of-function mutations in Pic14 developed less speck disease, specifically in older leaves, compared to wild-type plants. Transient expression of Pic14 in leaves of Nicotiana benthamiana and tomato inhibited cell death typically induced by Pto/Prf and the MAPK cascade members M3Kα and Mkk2. The cell death-suppressing activity of Pic14 was dependent on the KIM and the catalytic phosphatase domain. Pic14 inhibited M3Kα- and Mkk2-mediated activation of immunity-associated MAPKs and Pic14 was shown to be an active phosphatase that physically interacts with and dephosphorylates Mkk2 in a KIM-dependent manner. Together, our results reveal Pic14 as an important negative regulator of Pto/Prf-triggered immunity by interacting with and dephosphorylating Mkk2. SIGNIFICANCE STATEMENT Plant intracellular immune receptors, typically nucleotide-binding, leucine-rich repeat proteins (NLRs) such as the tomato Prf protein activate NLR-triggered immunity (NTI) in response to specific pathogen virulence proteins. This paper reveals how a protein phosphatase interacts with and dephosphorylates a key signaling component acting downstream of Pto/Prf, likely to moderate negative effects of NTI on growth or other plant processes.

Source: The Plant Journal

DOI: 10.1111/tpj.16937

Authors: Joydeep Chakraborty, Guy Sobol, Fan Xia, Ning Zhang, Gregory B. Martin, Guido Sessa

Institutions: Bose Institute, Tel Aviv University, Cornell University, Boyce Thompson Institute

Language: English

Topic: Plant-Microbe Interactions and Immunity

Subfield: Plant Science

Field: Agricultural and Biological Sciences

Domain: Life Sciences

SDG: Zero hunger

Open Access status: bronze

Funders: United States - Israel Binational Agricultural Research and Development Fund, Tel Aviv University