Chloroplasts play a central role in facilitating MAMP-triggered immunity, pathogen suppression of immunity and crosstalk with abiotic stress.

Microbe-associated molecular pattern (MAMP)-triggered immunity (MTI) research has traditionally centred around signal transduction pathways originating from activated membrane-localized pattern recognition receptors (PRRs), culminating in nuclear transcription and posttranslational modifications. More recently, chloroplasts have emerged as key immune signalling hubs, playing a central role in integrating environmental signals. Notably, MAMP recognition induces chloroplastic reactive oxygen species (cROS) that is suppressed by pathogen effectors, which also modify the balance of chloroplast-synthesized precursors of the defence hormones, jasmonic acid, salicylic acid (SA) and abscisic acid.