Structural biology of plant defence

Plants employ the innate immune system to discriminate between self and invaders through two types of immune receptors, one on the plasma membrane and the other in the intracellular space. The immune receptors on the plasma membrane are pattern recognition receptors (PRRs) that can perceive pathogen-associated molecular patterns (PAMPs) or host-derived damage-associated molecular patterns (DAMPs) leading to pattern-triggered immunity (PTI). Particular pathogens are capable of overcoming PTI by secreting specific effectors into plant cells to perturb different components of PTI signalling through various mechanisms. Most of the immune receptors from the intracellular space are the nucleotide-binding leucine-rich repeat receptors (NLRs), which specifically recognize pathogen-secreted effectors to mediate effector-triggered immunity (ETI). In this review, we will summarize recent progress in structural studies of PRRs, NLRs, and effectors, and discuss how these studies shed light on ligand recognition and activation mechanisms of the two types of immune receptors and the diversified mechanisms used by effectors to manipulate plant immune signalling.

Automated summary

Plants use both membrane-bound and intracellular immune receptors to distinguish self from invaders, initiating pattern-triggered immunity and effector-triggered immunity respectively. Pathogens can overcome pattern-triggered immunity by secreting effectors, which are specifically recognized by intracellular NLRs receptors.