Nanoselenium Foliar Applications Enhance the Nutrient Quality of Pepper by Activating the Capsaicinoid Synthetic Pathway

related enzymes and gene expressions. These led to an enhancement for the synthesis of capsaicinoids, flavonoids, and total phenols. The nano-Se treatment also significantly promoted the expression of phyto-hormones synthesis genes, and consequently increased jasmonic, abscisic, and salicylic acid levels. Proline pathway-related compounds were increased, which could decrease the malondialdehyde and hydroxyl radical levels in crops. This study shows that nano-Se activated capsaicinoid pathways by enhancing photosynthesis and raising soluble sugar levels. The capsaicinoid contents in peppers were then increased, which consequently promoted the accumulation of secondary metabolites and antioxidants.