A core function of EDS1 with PAD4 is to protect the salicylic acid defense sector in Arabidopsis immunity

• Published in: The New phytologist Vol. 213; no. 4; pp. 1802 - 1817
• Main Authors: Cui, Haitao, Gobbato, Enrico, Kracher, Barbara, Qiu, Jingde, Bautor, Jaqueline, Parker, Jane E.
• Format: Journal Article
• Language: English
• Published: England New Phytologist Trust 01-03-2017; Wiley Subscription Services, Inc
• Subjects: Arabidopsis - drug effects; Arabidopsis - genetics; Arabidopsis - immunology; Arabidopsis - microbiology; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Autoimmunity - drug effects; basal immunity; biotic stress network; Carboxylic Ester Hydrolases - metabolism; Cell Death - drug effects; Disease Resistance - drug effects; DNA-Binding Proteins - metabolism; effector‐triggered immunity (ETI); Estradiol - pharmacology; Gene Expression Regulation, Plant - drug effects; MAP Kinase Signaling System - drug effects; Models, Biological; Plant Diseases - genetics; Plant Diseases - microbiology; Plant Immunity - drug effects; Plants, Genetically Modified; RNA‐seq; Salicylic Acid - metabolism; Transcription, Genetic - drug effects; transcriptional reprogramming; Arabidopsis thaliana; biotic stress network; RNA-seq; transcriptional reprogramming; basal immunity; effector-triggered immunity (ETI)
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/nph.14302

Plant defenses induced by salicylic acid (SA) are vital for resistance against biotrophic pathogens. In basal and receptor-triggered immunity, SA accumulation is promoted by Enhanced Disease Susceptibility1 with its co-regulator Phytoalexin Deficient4 (EDS1/PAD4). Current models position EDS1/PAD4 upstream of SA but their functional relationship remains unclear.
In a genetic and transcriptomic analysis of Arabidopsis autoimmunity caused by constitutive or conditional EDS1/PAD4 overexpression, intrinsic EDS1/PAD4 signaling properties and their relation to SA were uncovered.
A core EDS1/PAD4 pathway works in parallel with SA in basal and effector-triggered bacterial immunity. It protects against disabled SA-regulated gene expression and pathogen resistance, and is distinct from a known SA-compensatory route involving MAPK signaling. Results help to explain previously identified EDS1/PAD4 regulated SA-dependent and SA-independent gene expression sectors.
Plants have evolved an alternative route for preserving SA-regulated defenses against pathogen or genetic perturbations. In a proposed signaling framework, EDS1 with PAD4, besides promoting SA biosynthesis, maintains important SA-related resistance programs, thereby increasing robustness of the innate immune system.