Making sense of plant autoimmunity and ‘negative regulators’

Abstract

Genetics studies the structure/function of genes via the characterization of their mutant phenotypes. In plants, a readily scorable mutant phenotype comprises macroscopic lesions symptomatic of disease in the absence of pathogens. Such mutants therefore exhibit autoimmune phenotypes. Many of these mutants are considered to be associated with immunity and the corresponding genes have been described as ‘negative regulators’ of immunity and/or cell death. Pathogens deliver effectors into host cells to increase infectivity by modifying or removing host proteins. Plants detect effectors via nucleotide‐binding, leucine‐rich repeat (NLR) immune receptors, which monitor host effector targets. In response to effector‐mediated target tampering, NLR proteins potentiate immunity. The guard hypothesis proposes that NLRs ‘guard’ host ‘guardees’ targeted by pathogen effectors. An obvious corollary to this guard model is that forms of plant autoimmunity are a result of inappropriate NLR protein activation. In this review, we discuss what is known about some of the ‘negative regulators’ of immunity, and propose simple strategies that may help to characterize autoimmune mutants.

Methylation of protein phosphatase 2A—Influence of regulators and environmental stress factors

“…PP2A is implicated in defence responses in Arabidopsis at the level of PAMP (pathogen‐associated molecular patterns) perception (Segonzac et al, ) and is a target of bacterial effector proteins (Jin et al, ). It is tempting to expect plant PP2A to be involved also in further downstream defence signalling by acting opposite to protein kinases and inhibiting MAPK signalling cascades, as has been found for MAPKs in mammalian cells (Asai et al, ; Junttila, Li, & Westermarck, ; Lassowskat, Bottcher, Eschen‐Lippold, Scheel, & Lee, ; Macho & Zipfel, ; Rodriguez, El Ghoul, Mundy, & Petersen, ). However, such targets of PP2A in plants still remain to be identified, and the basis for enrichment of defence genes in pme1 and lcmt1 needs further investigation.…”

Mighty Dwarfs: Arabidopsis Autoimmune Mutants and Their Usages in Genetic Dissection of Plant Immunity

“…They have been instrumental in assisting our studies of plant immunity. Previous reviews have highlighted lesion mimic mutants (Bruggeman et al, 2015; Rodriguez et al, 2016). Here we are focusing on Arabidopsis autoimmune mutants ( Table 1 ) and their application in studying plant immunity.…”

Identification of Rehmannia glutinosa L. NB-ARC family proteins and their typical changes under consecutive monoculture stress

“…Therefore, a correct time and place is required when ETI system performs immune function (Smith et al 2014). Previous studies have demonstrated that immune resistance disorder resulted from inappropriate NB-ARC protein activation (Rodriguez et al 2015). In this study, the NB-ARC genes expression was obviously up-regulated by 91.67% in SP2 stage, and serious death was correspondingly occurred (Fig.…”