Transcriptome and metabolome integrated analysis revealed the effects mechanism of preharvest arginine spraying on carbohydrate and energy metabolism in postharvest broccoli

Energy status plays a crucial role in the physiological processes of broccoli, and investigating its post-harvest energy and carbohydrate metabolic pathways can elucidate the mechanisms underlying freshness and nutrient accumulation. To assess the impact of arginine spraying one day prior to harvest on the post-harvest metabolic mechanisms of broccoli, we performed transcriptomic and metabolomic analyses. The results from both transcriptome and metabolome analyses indicated that arginine treatment up-regulated the expression levels of starch synthesis genes (StSy, GPAT) and sucrose synthesis genes (SPS), in addition to facilitated the production of glucose and fructose, thereby ensuring a stable supply of substrates for glycolytic pathways (EMP) as well as the pentose phosphate pathway (PPP), which is essential for maintaining broccoli quality. Furthermore, arginine treatment inhibited the degradation associated with cellulose-related genes (beta-glucosidase, EG) and D-galacturonic acid to preserve cell wall integrity. Additionally, it enhanced flux through EMP and PPP by up-regulating related gene expressions (FBP1, DDPFK, FBA, GAPD, PGK, TK). Under arginine treatment conditions, increased expression levels of MDH genes by 3.5 fold within the tricarboxylic acid cycle (TCA), resulting in rapid ATP synthesis. Along with augmented protein synthesis during oxidative phosphorylation (OXPHOS) significantly promoted ATP generation, which leading to an overall enhancement in energy status. Experimental findings demonstrated that broccoli treated with arginine maintained higher levels of ATP, ADP, and energy charge throughout storage periods. Thus it is evident that extending storage duration for broccoli via arginine application may be attributed to achieving a continuous and stable energy supply.