Chloroplast Function in Plant Immune Responses

Chloroplasts are central integrators of photosynthetic energy transduction and immune signalling in plants. Beyond their role in capturing light for ATP and NADPH production, chloroplasts synthesise defence‐related hormones such as salicylic acid and jasmonic acid and generate reactive oxygen species (ROS) that act as both antimicrobial agents and second messengers. Upon pathogen detection, chloroplasts alter gene expression programmes through retrograde signalling to the nucleus and remodel their morphology and position within cells via stromule formation. These dynamic changes support local hypersensitive cell death, systemic acquired immunity and modulation of primary metabolism, while also offering targets for pathogen effectors. Understanding chloroplast‐mediated defence pathways is therefore critical for breeding disease‐resistant crops and ensuring global food security.

Research from Nature Portfolio

Recent studies have revealed a specialised population of epidermal chloroplasts that mobilise dynamically in response to pathogen entry. These small organelles reposition toward sites of fungal penetration, regulated by conserved photorelocation proteins, in an epidermal chloroplast response that enhances preinvasive resistance. The targeted movement concentrates immune components at the first line of contact and is essential for nonhost defence. Disruption of this response diminishes antifungal immunity, highlighting a new mechanism by which chloroplast positioning and organelle dynamics contribute to plant protection.

Chloroplast Function in Plant Immune Responses publication trend

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

Technical terms

Reactive oxygen species (ROS): Highly reactive molecules produced by chloroplast electron transport that act as defence signals and antimicrobials.

Phytohormones: Small signalling molecules such as salicylic acid and jasmonic acid synthesised in chloroplasts to regulate immune responses.

Stromules: Tubular extensions of the chloroplast envelope that facilitate organelle interactions and signal transduction during stress.

Ubiquitination: Post-translational attachment of ubiquitin that can redirect proteins to chloroplasts or other cellular compartments.

Retrograde signalling: Communication from chloroplasts to the nucleus that modulates defence gene transcription in response to stimuli.

References

1. Accumulation of dually targeted StGPT1 in chloroplasts mediated by StRFP1, an E3 ubiquitin ligase, enhances plant immunity. Horticulture Research (2024).
2. Chloroplasts alter their morphology and accumulate at the pathogen interface during infection by Phytophthora infestans. The Plant Journal (2021).
3. Epidermal chloroplasts are defense-related motile organelles equipped with plant immune components. Nature Communications (2021).
4. Chloroplast Redox Status Modulates Genome-Wide Plant Responses during the Non-host Interaction of Tobacco with the Hemibiotrophic Bacterium Xanthomonas campestris pv. vesicatoria. Frontiers in Plant Science (2017).