Plant Immunity and Defense Mechanisms

Plants are continuously exposed to a myriad of microbial pathogens and herbivores, and have evolved multilayered defence strategies. The first layer, pattern‐triggered immunity (PTI), is activated when conserved microbial signatures called microbe‐associated molecular patterns (MAMPs) are perceived by cell‐surface receptors. Successful pathogens often deploy effector molecules to suppress PTI and colonise host tissue. In turn, plants have evolved intracellular nucleotide‐binding leucine‐rich repeat receptors (NLRs) that recognise specific effectors and trigger a robust effector‐triggered immunity (ETI), frequently culminating in a programmed cell‐death response that restricts pathogen spread. Signalling networks governed by phytohormones—particularly salicylic acid, jasmonic acid and ethylene—coordinate local and systemic defence gene expression. Recent work has highlighted the importance of post‐transcriptional and epigenetic regulation, such as alternative splicing and chromatin modifications, in fine‐tuning the amplitude and specificity of immune responses. These multilayered mechanisms underpin crop resistance to biotrophic, hemi‐biotrophic and necrotrophic pathogens, as well as herbivorous insects, with broad implications for sustainable agriculture and food security.

Research from Nature Portfolio

Recent studies have revealed new layers of host–microbe communication and immune regulation. One investigation demonstrated that effector proteins secreted by symbiotic arbuscular mycorrhizal fungi assemble in nuclear condensates and interact with core splicing machinery to reprogram alternative splicing of defence and symbiosis genes, suggesting that modulation of host RNA processing is a shared strategy among mutualists and pathogens. Additionally, structural and biochemical analysis of the immune regulator EDS1 has identified a conserved surface in its EP‐domain that is essential for signal transmission by both Toll/Interleukin‐1‐receptor‐domain NLRs and co-operating receptors. Mutations at this site delay transcriptional activation of defence genes and compromise resistance to bacterial and oomycete pathogens, providing critical insight into downstream NLR signalling and offering potential targets for engineering enhanced broad‐spectrum immunity.

Plant Immunity and Defense Mechanisms publication trend

The graph below shows the total number of articles in plant immunity and defense mechanisms across all publications each year (not limited to Nature Index journals).

Technical terms

Pattern-Triggered Immunity (PTI): the plant’s first line of defence activated by cell-surface receptors recognising conserved microbial signatures.

Effector-Triggered Immunity (ETI): a robust intracellular immune response initiated when NLR receptors detect specific pathogen effectors, often involving programmed cell death.

NLR receptor: a class of intracellular immune receptors with nucleotide-binding and leucine-rich repeat domains that monitor effector activity.

Microbe-Associated Molecular Pattern (MAMP): a conserved microbial molecule, such as flagellin or peptidoglycan, recognised by plant pattern-recognition receptors.

Salicylic acid (SA): a phytohormone central to defence against biotrophic pathogens and systemic acquired resistance signalling.

Alternative splicing: the process by which precursor mRNA transcripts are variably processed to generate multiple protein isoforms, modulating defence gene functions.

References

1. Alternative splicing regulation in plants by SP7-like effectors from symbiotic arbuscular mycorrhizal fungi. Nature Communications (2024).
2. Plant latent defense response against compatibility. The ISME Journal: Multidisciplinary Journal of Microbial Ecology (2023).
3. Network Properties of Robust Immunity in Plants. PLOS Genetics (2009).
4. Genetic modification to improve disease resistance in crops. New Phytologist (2019).
5. An EDS1 heterodimer signalling surface enforces timely reprogramming of immunity genes in Arabidopsis. Nature Communications (2019).