EDR1 associates with its homologs to synergistically regulate plant immunity in Arabidopsis. (May 2023)

• Record Type: Journal Article
• Authors: Zhong, Guitao; Chen, Yongming; Liu, Simu; Gao, Chenyang; Chen, Renjie; Wang, Zhanchun; Wang, Wei; Tang, Dingzhong
• Is Part Of: Plant science. Volume 330(2023)
• Publication Date: 2023-05
• Subjects: Plant immunity -- EDR1 -- Raf-like kinase -- SA -- Pto DC3000 -- Powdery mildew; Botany -- Periodicals; Botanique -- Périodiques; 580
• DOI: 10.1016/j.plantsci.2023.111619
• Languages: English
• ISSNs: 0168-9452

Abstract

Abstract: 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. Highlights: The edr1 raf3 / 4 / 5 mutant displays enhanced resistance to pathogens than edr1 . The edr1 raf3 / 4 / 5 mutant exhibits higher MPK3/6 activation than edr1 after infection with pathogens. SID2 contributes to the robust resistance in the edr1 raf3 / 4 / 5 mutant. EDR1 associates with RAF3/4/5 to form a Raf-like kinase complex. RAF3/4/5 function together with EDR1 in plant immunity regulation by suppressing MAPK cascades activation.