EDR1 associates with its homologs to synergistically regulate plant immunity in Arabidopsis.

ENHANCED DISEASE RESISTANCE 1 (EDR1), a Raf-like mitogen-activated protein kinase (MAPK) kinase kinase (MAPKKK), is a negative regulator of resistance. There are three homologs, RAF3/4/5, of EDR1 in Arabidopsis. However, the roles of RAF3/4/5 in resistance and their functional link with EDR1 in plant immunity remain unclear. Here, we showed that the raf3/4/5 triple mutant displayed wild-type-like phenotypes to the powdery mildew pathogen Golovinomyces cichoracearum UCSC1 and the bacterial pathogen Pseudomonas syringae pv. tomato (Pto) DC3000. However, the edr1 raf3/4/5 quadruple mutant exhibited enhanced resistance to G. cichoracearum UCSC1 and Pto DC3000 compared to edr1. Consistently, MPK3/6 kinase activity was more highly activated in edr1 raf3/4/5 than that in edr1. Moreover, the enhanced resistance of edr1 raf3/4/5 required SALICYLIC ACID INDUCTION DEFICIENT 2 (SID2), an isochorismate synthase required for salicylic acid (SA) synthesis. Additionally, unlike EDR1, RAF3/4/5 weakly and indirectly associated with MKK4/5, and EDR1 was directly associated with RAF3/4/5. Taken together, these data indicate that EDR1 associates with RAF3/4/5, and they may function together to synergistically suppress MAPK cascades activation, which reveal the complexity and importance of Raf-like MAPKKKs in plant immunity regulation. Copyright © 2023 Elsevier B.V. All rights reserved.

Citation

Guitao Zhong, Yongming Chen, Simu Liu, Chenyang Gao, Renjie Chen, Zhanchun Wang, Wei Wang, Dingzhong Tang. EDR1 associates with its homologs to synergistically regulate plant immunity in Arabidopsis. Plant science : an international journal of experimental plant biology. 2023 May;330:111619

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PMID: 36737004

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