Cloning, in silico characterization, subcellular localization, and expression of a heat shock cognate 70 kDa protein/gene (EjHsc70-2) from Eriobotrya japonica

Abstract

Heat shock protein 70 kDa proteins (Hsp70 s) are among the most important molecular chaperone groups and play a significant role in the stress responses and development of plants. In the present study, the full-length cDNA of the heat shock cognate 70 protein 2 gene EjHsc70-2, which encodes a loquat Hsp70 s member, was cloned and characterized, and its expression and subcellular localization were also investigated. The full-length cDNA of EjHsc70-2 consists of an open reading frame (ORF) of 1950 bp, a 5′-UTR of 103 bp, and a 3′-UTR of 62 bp, and the ORF encodes 649 amino acid residues. The structure of the loquat Hsc70-2 protein was analysed using several bioinformatics tools, and the results showed that the protein was, indeed, a member of the Hsp70 s. Phylogenetic tree analysis suggested that the genetic evolution of Hsc70-2 genes conformed well to the morphology based taxonomic classification of seed plants. BLAST and multiple alignment analyses determined that the Hsc70-2 genes and Hsc70-2 proteins were both highly conserved among loquat and other seed plants, suggesting that the functions of EjHsc70-2 might be similar to those of other Hsc70-2 genes. The bioinformatics and experimental subcellular localization analyses both supported that EjHsc70-2 was a cytoplasmic and/or nuclear protein. Quantitative real-time RT-PCR (RT-qPCR) suggested its conserved functions involved in loquat organ development. Moreover, EjHsc70-2 were also inducible, which may contribute to the low-temperature adaptation of loquat fruits in cold storage. These results provide new insights into the characteristics and functions of Hsp70 s in Eriobotrya japonica.