Photosynthetic Responses to Plant Pathogen Interactions

Photosynthetic performance in plants is profoundly influenced by pathogen challenge, with both biotrophic and necrotrophic infections triggering a cascade of stomatal, metabolic and signalling responses. Initial pathogen recognition often induces stomatal closure, limiting CO₂ uptake and precipitating rapid declines in photosynthetic carbon assimilation. Concurrently, reactive oxygen species accumulate in chloroplasts as part of defence programmes, impairing electron transport and prompting non-photochemical quenching to dissipate excess energy. Many pathogens deploy specialised effectors that target chloroplast membranes or photosynthetic enzymes, further compromising light reactions and carbon fixation. At the same time, host plants may reprogramme chloroplast-to-nucleus retrograde signalling to bolster antioxidant capacity and adjust metabolic fluxes towards defence compound synthesis. The balance between maintaining photosynthetic productivity and activating immune pathways underpins crop resilience, informing breeding strategies for minimal yield penalty during disease outbreaks. A comprehensive understanding of these intertwined processes is central to mitigating global crop losses and sustaining food security.

Research from Nature Portfolio

Recent studies have shown that fungal effectors can rewire chloroplast electron transport by binding to photosystem I proteins, leading to targeted suppression of ATP generation while sparing defence-related signalling. Another investigation revealed that bacterial infection induces systemic redox waves propagating from infected leaves to distant chloroplasts, coordinating whole-plant stomatal adjustments and enabling pre-emptive defence activation. In addition, analysis of plastid-nucleus communication has uncovered a role for chloroplast-derived metabolites in fine-tuning transcriptional responses, thereby linking light harvesting efficiency with immune gene expression and facilitating a dynamic trade-off between growth and resistance.

Photosynthetic Responses to Plant Pathogen Interactions publication trend

The graph below shows the total number of articles in photosynthetic responses to plant pathogen interactions across all publications each year (not limited to Nature Index journals).

Technical terms

Non-photochemical quenching (NPQ): A mechanism by which excess light energy is harmlessly dissipated as heat in the chloroplast to protect the photosynthetic apparatus.

Retrograde signalling: Communication from chloroplasts to the nucleus involving metabolites or reactive species that adjust nuclear gene expression.

Mesophyll conductance: The ease with which CO₂ diffuses from the substomatal cavity through the mesophyll to the carboxylation sites in chloroplasts.

Virtual lesion effect: Photosynthetic inhibition in apparently healthy tissue surrounding a visible lesion, due to diffusible signals or resource depletion.

Reactive oxygen species (ROS): Highly reactive molecules produced during stress that function in defence signalling but can damage cellular components if uncontrolled.

References

1. Phakopsora euvitis Causes Unusual Damage to Leaves and Modifies Carbohydrate Metabolism in Grapevine. Frontiers in Plant Science (2017).
2. Inhibition of photosynthesis by Colletotrichum lindemuthianum in bean leaves determined by chlorophyll fluorescence imaging. Plant Cell & Environment (2001).
3. Photosynthetic properties and biochemical metabolism of Cucurbita moschata genotypes following infection with powdery mildew. Journal of Plant Pathology (2020).