Integrated transcriptome and metabolome analyses shed light on the defense mechanisms in tomato plants after (E)-2-hexenal fumigation.

Tomato is a widely cultivated fruit and vegetable and is valued for its flavor, colour, and nutritional value. C-aldehydes, such as (E)-2-hexenal, not only have antibacterial and antifungal properties but also function as signaling molecules that control the defense mechanisms of plants, including tomatoes. In this study, we used liquid chromatography-mass spectrometry (LC-MS) and RNA sequencing techniques to generate metabolome and transcriptome datasets that elucidate the molecular mechanisms regulating defense responses in tomato leaves exposed to (E)-2-hexenal. A total of 28.27 Gb of clean data were sequenced and assembled into 23,720 unigenes. In addition, a non-targeted metabolomics approach detected 739 metabolites. There were 233 significant differentially expressed genes (DEGs) (158 up-regulated, 75 down-regulated) and 154 differentially expressed metabolites (DEMs) (86 up-regulated, 69 down-regulated). Most nucleotides and amino acids (L-Phenylalanine, L-Asparagine, L-Histidine, L-Arginine, and L-Tyrosine) and their derivatives were enriched. The analyses revealed that mitogen-activated protein kinase (MPK), pathogenesis-related protein (PR), and endochitinase (CHIB) were primarily responsible for the adaptation of plant defense responses. Therefore, the extensive upregulation of these genes may be associated with the increased plant defense response. These findings help us comprehend the defense response of plants to (E)-2-hexenal and improve the resistance of horticultural plants.