Epsilon-poly-<scp>l</scp>-lysine increases disease resistance of citrus against postharvest green mold by activating amino acid metabolism and phenolic compounds biosynthesis

Abstract As a famous fruit worldwide, citrus is susceptible to green mold caused by Penicillium digitatum, which causes large economic losses every year. ε-Poly-l-lysine (ε-PL) novel preservative with strong inhibitory effects on fungi, and has the capacity induce disease resistance in fruit, but mechanism been reported rarely, especially citrus. In present study, 800 μg/mL ε-PL P. digitatum spores were inoculated two different wounds pericarp at an interval of 24 h. The results revealed that inhibited development without direct contact indicating was activated. Transcriptome analysis activated amino acid metabolism phenylpropanoid biosynthesis. Besides, accumulation glutamic acid, proline, arginine, serine, lysine, phenylalanine, tyrosine changed during storage. biosynthesis, increased phenylalanine ammonia-lyase (PAL), cinnamate 4-hydroxylase (C4H), 4-coumarate:coenzyme A ligase (4CL) activities total phenolic flavonoid contents. Importantly, among these compounds, promoted individual compounds including ferulic chlorogenic p-coumaric caffeic gallic catechins, epicatechin, narirutin. conclusion, enhanced through compounds. These improved knowledge ε-PL–induced provided fresh theoretical basis for use postharvest preservation.