Search

Summary: Autoimmunity in plants has been found in numerous hybrids as a form of hybrid necrosis and mutant panels. Uncontrolled cell death is a main cellular outcome of autoimmunity, which negatively impacts growth. Its occurrence highlights the vulnerable nature of the plant immune system. Genetic investigation of autoimmunity in hybrid plants revealed that extreme variation in the immune receptor repertoire is a major contributor, reflecting an evolutionary conundrum that plants face in nature. In this review, we discuss natural variation in the plant immune system and its contribution to fitness. The value of autoimmunity genetics lies in its ability to identify combinations of a natural immune receptor and its partner that are predisposed to triggering autoimmunity. The network of immune components for autoimmunity becomes instrumental in revealing mechanistic details of how immune receptors recognize cellular invasion and activate signaling. The list of autoimmunity‐risk variants also allows us to infer evolutionary processes contributing to their maintenance in the natural population. Our approach to autoimmunity, which integrates mechanistic understanding and evolutionary genetics, has the potential to serve as a prognosis tool to optimize immunity in crops. [ABSTRACT FROM AUTHOR]

Summary: Pattern recognition receptors (PRRs) sense microbial patterns and activate innate immunity against attempted microbial invasions. The leucine‐rich repeat receptor kinases (LRR‐RK) FLS2 and EFR, and the LRR receptor protein (LRR‐RP) receptors RLP23 and RLP42, respectively, represent prototypical members of these two prominent and closely related PRR families.We conducted a survey of Arabidopsis thaliana immune signaling mediated by these receptors to address the question of commonalities and differences between LRR‐RK and LRR‐RP signaling.Quantitative differences in timing and amplitude were observed for several early immune responses, with RP‐mediated responses typically being slower and more prolonged than those mediated by RKs. Activation of RLP23, but not FLS2, induced the production of camalexin. Transcriptomic analysis revealed that RLP23‐regulated genes represent only a fraction of those genes differentially expressed upon FLS2 activation. Several positive and negative regulators of FLS2‐signaling play similar roles in RLP23 signaling. Intriguingly, the cytoplasmic receptor kinase BIK1, a positive regulator of RK signaling, acts as a negative regulator of RP‐type immune receptors in a manner dependent on BIK1 kinase activity.Our study unveiled unexpected differences in two closely related receptor systems and reports a new negative role of BIK1 in plant immunity. [ABSTRACT FROM AUTHOR]