Arabidopsis SENESCENCE-ASSOCIATED GENE101 Stabilizes and Signals within an ENHANCED DISEASE SUSCEPTIBILITY1 Complex in Plant Innate Immunity

Abstract

Plant innate immunity against invasive biotrophic pathogens depends on the intracellular defense regulator ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1). We show here that Arabidopsis thaliana EDS1 interacts in vivo with another protein, SENESCENCE-ASSOCIATED GENE101 (SAG101), discovered through a proteomic approach to identify new EDS1 pathway components. Together with PHYTOALEXIN-DEFICIENT4 (PAD4), a known EDS1 interactor, SAG101 contributes intrinsic and indispensable signaling activity to EDS1-dependent resistance. The combined activities of SAG101 and PAD4 are necessary for programmed cell death triggered by the Toll-Interleukin-1 Receptor type of nucleotide binding/leucine-rich repeat immune receptor in response to avirulent pathogen isolates and in restricting the growth of normally virulent pathogens. We further demonstrate by a combination of cell fractionation, coimmunoprecipitation, and fluorescence resonance energy transfer experiments the existence of an EDS1-SAG101 complex inside the nucleus that is molecularly and spatially distinct from EDS1-PAD4 associations in the nucleus and cytoplasm. By contrast, EDS1 homomeric interactions were detected in the cytoplasm but not inside the nucleus. These data, combined with evidence for coregulation between individual EDS1 complexes, suggest that dynamic interactions of EDS1 and its signaling partners in multiple cell compartments are important for plant defense signal relay.

De novo assembly of soybean wild relatives for pan-genome analysis of diversity and agronomic traits

“…Fatty acids are precursors for jasmonate production in the oxylipin pathway in plants following stress 36 . SAG101 (senescence-associated gene101) in Arabidopsis, which encodes a triacylglycerol lipase to hydrolyze triacylglycerol to monoacylglycerol and produce free fatty acid, plays important roles in plant innate immunity against biotrophic pathogens 37 . In this study, large-effect SNP and/or indels were found in three clustered homologs of SAG101 (Glyma13g04561, Glyma13g04651 and Glyma13g04571) and are candidate genes for nearby QTL that affect oil content and confer resistance to Phytophthora sojae 38 (Supplementary Fig.…”

Insights into Nonhost Disease Resistance: Can They Assist Disease Control in Agriculture?

“…Posthaustorial resistance is dependent on genes including PAD4, EDS1, and SAG101 (Lipka et al, 2005;Stein et al, 2006), which are involved in the basal resistance pathways that restrict rampant disease development during compatible host-pathogen interactions and also in some R gene pathways leading to the HR (Parker et al, 1996;Feys et al, 2005). Single mutants of pad4, eds1, and sag101 have little effect on the frequency of Bgh haustoria formation in Arabidopsis.…”

“…The involvement of the HR and EDS1/PAD4/SAG101, necessary for both basal resistance and resistance mediated by one of two classes NBS-LRR R proteins (Parker et al, 1996;Feys et al, 2005), indicates possible R protein activity in Bgh-Arabidopsis nonhost interactions. However, data counter to this view are provided by Stein et al (2006).…”

Potential role of salicylic acid in modulating diacylglycerol homeostasis in response to freezing temperatures in Arabidopsis

“…5,8 EDS1 physically interacts with PAD4 and SAG101 to contribute to HR formation and defense signaling. 9,10,11 They form a ternary complex in the nucleus to regulate plant defense response. 11,12 In addition, SAG101 and PAD4 share a role in modulating the subcellular localization of EDS1.…”

“…9,10,11 They form a ternary complex in the nucleus to regulate plant defense response. 11,12 In addition, SAG101 and PAD4 share a role in modulating the subcellular localization of EDS1. 12 Although the roles of SAG101, EDS1, and PAD4 in biotic stress response have been extensively studied, little is known about their functions in plant responses to abiotic stresses.…”