Multi-omics reveals the regulatory mechanism of nutrients accumulation in broccoli head under preharvest arginine application.

Preharvest nutrient accumulation and the related metabolic processes play a crucial role in determining the quality and shelf life of broccoli, which in turn influence its freshness, nutritional value, and overall marketability. However, the regulatory mechanisms underlying these processes remain unclear. In this study, we investigated the effects of preharvest florets application of 5 mM arginine (ARG) five days prior to harvest, on nutrient accumulation, pigment metabolism, and the maintenance of postharvest quality in broccoli heads. Our results showed that the application of ARG significantly enhanced the levels of chlorophyll, carotenoids, and fructose during the preharvest stage of broccoli. Moreover, transcriptomic analysis revealed that ARG treatment significantly upregulated the expression of genes related to photosynthesis, carbohydrate metabolism, and pigment biosynthesis. Consequently, preventing chlorophyll and carotenoids from oxidative damage maintains the stability of photosystems (PSI and PSII), enhances photosynthetic efficiency, and delays postharvest yellowing. Additionally, up-regulated the expression of sucrose phosphate synthase and 1,4-α-glucan-branching enzyme, hence facilitating carbohydrate accumulation. In addition, ARG application downregulated the expression level of cellulose degradation genes, contributing to the maintenance of cell wall structure. This study provides a theoretical basis for the intrinsic mechanisms of postharvest preservation and preharvest nutrient accumulation in broccoli.