Linking high light-induced transcriptome profiling of fruit and leaf mesophyll with postharvest traits in tomato

Abstract

The transcriptional responses of plants to high light (HL) are dynamic and specific, varying with exposure duration, growth stage, and tissue type. However, the mechanisms linking transcriptomic and physiological responses in tomato leaves (source) and fruits (sink) remain relatively unknown. Here, transcriptome profiling of tomato fruit tissue and leaf mesophyll cell protoplasts (MCP) identified differentially expressed genes (DEGs) involved in the metabolic and signaling pathways under HL. Gene and pathway enrichment analyses revealed distinct strategies: we observed reprogramming of primary metabolism and N-glycan biosynthesis in fruits, while flavonoid and terpenoid pathways were activated in leaf MCP. Furthermore, cell wall metabolism-associated genes associated with ascorbic acid accumulation were markedly regulated under HL, which may facilitate reactive oxygen species detoxification, contribute to the softening of fruit texture, and consequently influence overall tomato fruit quality. These DEGs included GDP-L-galactose phosphorylase (SlGGP), ascorbate peroxidases (SlAPXs), ripening inhibitor, a MADS-box transcription factor (SlRIN), and abscisic acid stress ripening 1 (SlASR1). Moreover, HL-triggered molecular regulation in MCP is closely linked to tomato fruit quality traits, through the coordinated expression of both common and specific DEGs such as Small Auxin Up RNA 1 (SAUR1) and Phenylalanine ammonia-lyase (PLA). Furthermore, the weighted gene co-expression network analysis (WGCNA) revealed that distinct gene modules were significantly correlated with key fruit quality traits in HL compared to the control. These findings suggest that light intensity-dependent transcriptional reprogramming of metabolic and signaling networks contributes to HL acclimation of tomato fruit quality in greenhouse conditions.