The Tomato <i>ddm1b</i> Mutant Shows Decreased Sensitivity to Heat Stress Accompanied by Transcriptional Alterations

Heat stress is a major environmental factor limiting crop productivity, thus presenting a food security challenge. Various approaches are taken in an effort to develop crop species with enhanced tolerance to heat stress conditions. Since epigenetic mechanisms were shown to play a regulatory role in mediating plants’ responses to their environment, we investigated the role of DNA methylation in response to heat stress in tomato (Solanum lycopersicum), an important vegetable crop. To meet this aim, we tested a DNA methylation-deficient tomato mutant, Slddm1b. In this short communication paper, we report phenotypic and transcriptomic preliminary findings, implying that the tomato ddm1b mutant is significantly less sensitive to heat stress compared with the background tomato line, M82. Under conditions of heat stress, this mutant line presented higher fruit set and seed set rates, as well as a higher survival rate at the seedling stage. On the transcriptional level, we observed differences in the expression of heat stress-related genes, suggesting an altered response of the ddm1b mutant to this stress. Following these preliminary results, further research would shed light on the specific genes that may contribute to the observed thermotolerance of ddm1b and their possibly altered DNA methylation status