Dynamic changes to the plastoglobule lipidome and proteome in heat-stressed maize

Heat stress is a major environmental factor affecting the physiology and productivity of agricultural crops including maize (Zea mays). Plastoglobules, lipid-protein structures in chloroplasts, play a key role in stress resilience by modulating lipid metabolism and maintaining chloroplast function. However, the molecular functions of plastoglobules and their compositions are enigmatic. Our study investigated the molecular changes in the protein and lipid compositions of plastoglobules and thylakoids at six time points over the course of an imposed heat stress and recovery treatment in B73 inbred maize. Results indicate a progressive increase in plastoglobule size and number, and proliferation of adjacent cytosolic lipid droplets, correlating with the duration of heat exposure. Significant alterations in lipid composition, particularly in levels of triacylglycerol, plastoquinone derivatives (PQ-C, B & E) and the fatty acid phytol ester, 12:0-phytol, suggest a protective role in membrane remodeling and oxidative defense. Furthermore, heat-induced upregulation of key plastoglobule-associated proteins, such as Fibrillin 1a & 2, Fructose-bisphosphate Aldolase 2, 13-Lipoxygenase 10/11, and Allene Oxide Synthase 2b were observed, indicating their involvement in stress mitigation. These findings provide novel insights into the adaptive mechanisms of plastoglobules under heat stress in the context of remodeling at the thylakoid and highlight potential targets for improving maize resilience and leveraging the plastoglobules for crop improvement. Understanding these responses could contribute to developing heat-resilient maize cultivars in the face of global climate change.