Genome-wide analysis of Hsp70 and Hsp100 gene families in Ziziphus jujuba.

The Ziziphus species are naturally tolerant to a range of abiotic stresses. Therefore, it is expected that they are an enriched source of genes conferring stress tolerance. Heat shock proteins (Hsps) play a significant role in plants in imparting tolerance against abiotic stress conditions. To get an insight into potential Hsp function in Ziziphus, we performed a genome-wide analysis and expression study of Hsp70 and Hsp100 gene families in Ziziphus jujuba. We identified 21 and 6 genes of the ZjHsp70 and ZjHsp100 families, respectively. Physiochemical properties, chromosomal location, gene structure, motifs, and protein domain organization were analysed for structural and functional characterization. We identified the contribution of tandem and segmental gene duplications in expansions of ZjHsp70s and ZjHsp100s in Z. jujuba. Promoter analysis suggested that ZjHsp70s and ZjHsp100s perform diverse functions related to abiotic stress. Furthermore, expression analyses revealed that most of the Z. jujuba Hsp genes are differentially expressed in response to heat, drought, and salinity stress. Our analyses suggested ZjHsp70-3, ZjHsp70-5, ZjHsp70-6, ZjHsp70-16, ZjHsp70-17, ZjHsp70-20, ZjHsp100-1, ZjHsp100-2, and ZjHsp100-3 are potential candidates for further functional analysis and with regard to breeding new more resilient strains. The present analysis laid the foundation for understanding the molecular mechanism of Hsps70 and Hsp100 gene families regulating abiotic stress tolerance in Z. jujuba.