Determination of metabolite changes associated with heat stress in ethanol treated vs non-treated control tomato plants. Solanum lycopersicum

Chemical priming has emerged as a promising area in agricultural research. Our previous studies have demonstrated that pretreatment with low concentration of ethanol enhances abiotic stress tolerance mainly in Arabidopsis and cassava. Here, we present that ethanol treatment induces heat stress tolerance in tomato (Solanum lycopersicon L.) plants. Seedlings of the tomato cultivar Micro-tom were pretreated with ethanol solution and then subjected to heat stress. The survival rates of the ethanol-pretreated plants were significantly higher than those of the water-treated ones. Similarly, the fruit numbers of the ethanol-pretreated plants were increased compared to those of the water-treated ones. Transcriptome analysis identified the sets of genes that were differentially expressed in the ethanol-pretreated shoots and roots at a seedling stage and fruits at a mature green fruit stage compared to the water-pretreated ones. GO analysis using these genes showed that stress-related GO terms were found in the set of ethanol-induced genes. Metabolome analysis revealed that the contents of a wide range of metabolites were different between water- and ethanol-treated samples. They included some sugars such as trehalose, sucrose, glucose, and fructose. From these results, we speculate that the ethanol-induced heat stress tolerance in tomato is mainly due to the increased expressions of stress-related genes encoding late embryogenesis abundant (LEA) protein and reactive oxygen species (ROS) elimination enzyme and the activated gluconeogenesis. The knowledge presented here will be useful for establishing the ethanol-based chemical priming technology that reduce heat stress damage in crops, especially in Solanaceae.