Transcriptome profiles of eggplant (Solanum melongena) and its wild relative S. dasyphyllum under different levels of osmotic stress provide insights into response mechanisms to drought

Defence mechanisms to abiotic stresses, like drought, are very broad and RNA sequencing (RNA-Seq) can help in understanding the complex responses triggered. In this study, we performed RNA-Seq of the transcriptomes of eggplant (Solanum melongena) and its related wild species (S. dasyphyllum) under two PEG concentrations (20% and 30%), two different times (after 0.5 h and 2 h of osmotic stress) and at two plant phenological stages (three and five true fully developed leaves). Solanum dasyphyllum was more tolerant to osmotic stress, and a differential expression pattern of drought-related genes was identified between the two species. Plants subjected to a higher osmotic potential, at a more adult stage and at a higher stress exposure time displayed a higher number of DEGs (differential expressed genes). Gene ontology (GO) enrichment analysis revealed that, compared to S. melongena, S. dasyphyllum triggered the regulation of a wide range of transcription factors (AP2/ERF, DREB, bZIP, WRKY and bHLH). In both species, the abscisic acid (ABA) signaling response pathway played a crucial role leading to stomatal closure. Other important pathways involved in abiotic stresses tolerance including flavonoid, carotenoid and phenylpropanoid biosynthesis, chlorophyll metabolism and photosynthesis pathway among others were found to have a relevant role under both moderate and severe osmotic stresses. Our results reveal that S. dasyphyllum is a potential source of genes for breeding resilient eggplant varieties.