Transcriptomic and proteomic analysis reveals (E)-2-hexenal modulates tomato resistance against Botrytis cinerea by regulating plant defense mechanism.

In a previous study, we observed that (E)-2-hexenal stimulated systemic resistance against B. cinerea in tomato plants. However, the molecular mechanisms underlying (E)-2-hexenal-mediated regulation of systemic immunity against B. cinerea remained unclear. In the current study, the global mechanism underlying (E)-2-hexenal-meidated regulation of biotic stress tolerance in tomato was investigated using RNA-seq- and LC-MS/MS- integrated transcriptomic and proteomic analyses. Compared to control plants, (E)-2-hexenal-treated plants exhibited reduced susceptibility to B. cinerea, with a 50.51% decrease in lesion diameters. Meanwhile, (E)-2-hexenal vapor fumigation significantly increased total phenolic content and activities of various antioxidant enzymes peroxidase (POD), phenylalanine ammonia lyase (PAL), and lipoxygenase (LOX). A total of 233 differentially expressed genes (DEGs) and 400 differentially expressed proteins (DEPs), respectively, were identified. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that (E)-2-hexenal treatment markedly affected the expression of genes involved in multiple metabolic pathways, especially glutathione metabolism, phenylpropanoid biosynthesis, plant hormone signal transduction, and MAPK signaling pathway. Notably, proteomic analysis revealed modulation of the activities of several defense response proteins, such as pathogenesis-related (PR) proteins (Solyc02g031950.3.1, Solyc02g031920.4.1, and Solyc04g064870.3.1), peroxidases (Solyc06g050440.3.1, Solyc01g105070.3.1, Solyc01g015080.3.1, Solyc03g025380.3.1 and Solyc06g076630.3.1). Our results provide a comprehensive analysis of the effects of (E)-2-hexenal treatment on the transcriptome and proteome of tomato plants, which might be used as a reference in further studies on plant defense responses against pathogens.