Multi-omics analysis reveals distinct responses to light stress in photosynthesis and primary metabolism between maize and rice.

High light (HL) stress is a significant environmental factor limiting crop productivity. Maize (Zea mays) and rice (Oryza sativa), two key global crops, can both grow under high light intensities, but differ in photosynthetic metabolism, with maize being a C species and rice a C species. However, the molecular mechanisms underlying their responses to HL stress remain poorly understood. To systematically dissect how HL affects growth of maize and rice, we carried out time-resolved multi-omics analyses, examining the transcriptome, translatome, proteome and metabolome in response to HL treatment. Combining this multi-omics approach with physiological analyses, we found that rice exhibits a more rapid response to HL stress than maize, with significant alteration in photosynthetic electron transport, energy dissipation, reactive oxygen species (ROS) accumulation, and primary metabolism. In contrast, the higher tolerance to HL stress of maize is primarily attributed to increased cyclic electron flow (CEF) and non-photochemical quenching (NPQ), elevated sugar and aromatic amino acid accumulation, and enhanced antioxidant activity during a 4-hour HL exposure. Transgenic experiments further validated key regulators of HL tolerance; for instance, knock-out of OsbZIP18 enhanced HL tolerance in rice, while overexpression of ZmPsbS in maize significantly boosted photosynthesis and energy-dependent quenching (qE) after 4 hours HL treatment, underscoring its role in protecting C crops from HL-induced photodamage. Together, these findings offer new insights into the molecular mechanisms of HL stress tolerance in C versus C species, and highlight a set of candidate genes for engineering improved HL tolerance in crops.