Photorespiration and plant immunity: Interactions and implications under a changing climate.

Climate change has profound impacts on plant growth, productivity, and immunity. Photosynthesis, a key biological process that sequesters atmospheric CO2, plays a crucial role in mitigating the effects of climate change. However, photorespiration, a process that consumes O2 instead of CO2 and is metabolically linked with photosynthesis, is often viewed as a wasteful process that reduces photosynthetic efficiency by nearly 48 % in C3 plants. This reduction has a significant impact on crop yield, given the direct contribution of photosynthesis to biomass accumulation. Over the years, numerous efforts have been made to rectify this perceived metabolic flaw to enhance photosynthetic efficiency. Interestingly, recent studies have unveiled a role for photorespiration in plant immunity, which can vary from positive to negative depending on the plant-pathosystem. A key challenge lies in enhancing photosynthetic efficiency by modulating photorespiration without compromising plant immunity. This review discusses the role of photorespiration in plant immunity under current and future climatic conditions. We explore how photorespiration and photorespiratory pathways influence plant defense, how alterations in photorespiration affect hormonal pathways and subsequently plant immunity, and how manipulations of photorespiration may impact plant growth and defense under elevated CO2 conditions. We highlight the roles of plant hormones such as salicylates and jasmonates as well as reactive oxygen species, in photorespiration-related plant immunity. We conclude that unraveling the underlying mechanisms of photorespiration-involved plant responses to various pathogens provides comprehensive insights for the management, breeding, and genetic improvement of crops, thereby enhancing their resilience to future climate change.