NGS-Based Expression Profiling of HSP Genes During Cold and Freeze Stress in Seabuckthorn (Hippophae rhamnoides L.)

Abstract

Expression of many Heat Shock Protein (HSP) genes triggers in plant cells when exposed to abiotic stresses. An important exercise towards understanding the mechanism of plants response to cold and freeze stress is the identification of genes responsible for cold and freeze tolerance in plants adapted to low temperature climates. Seabuckthorn (Hippophae rhamnoides L.) is one such plant species that sustains growth in extreme temperature environments. We performed complete transcriptome profiling of leaf and root tissues of seabuckthorn using Illumina Next Generation Sequencing. The seabuckthorn transcriptome data revealed the presence of 205 heat shock protein and their co-protein coding genes. Later, DeepSAGE, a tag based approach, was used to identify differentially expressed genes coding for HSPs and their co-proteins under cold and freeze stress. The DeepSAGE data revealed differential expression of 13 genes under cold stress (CS) and 9 genes under freeze stress (FS) with respect to control (CON). Similarly, 14 genes were differentially expressed under FS with respect to CS. Expression of the most abundant hsp70 gene was validated using qRT-PCR under different stress treatments. Our results may assist future efforts aiming towards understanding the role of HSP genes in mediating cold and freeze stress in crop plants.