Evolutionary analysis and expression profiling of the HSP70 gene family in response to abiotic stresses in tomato (Solanum lycopersicum)

Heat shock protein 70 (HSP70) genes play essential roles in guarding plants against abiotic stresses, including heat, drought, and salt. In this study, the SlHSP70 gene family in tomatoes has been characterized using bioinformatic tools. 25 putative SlHSP70 genes in the tomato genome were found and classified into five subfamilies, with multi-subcellular localizations. Twelve pairs of gene duplications were identified, and segmental events were determined as the main factor for the gene family expansion. Based on public RNA-seq data, gene expression analysis identified the majority of genes expressed in the examined organelles. Further RNA-seq analysis and then quantitative RT-PCR validation showed that many SlHSP70 members are responsible for cellular feedback to heat, drought, and salt treatments, in which, at least five genes might be potential key players in the stress response. Our results provided a thorough overview of the SlHSP70 gene family in the tomato, which may be useful for the evolutionary and functional analysis of SlHSP70 under abiotic stress conditions.