Comparative genomic analysis reveals expansion of the DnaJ gene family in Lagerstroemia indica and its members response to salt stress.

DnaJs/Hsp40s/JPDs are obligate co-chaperones of heat shock proteins (Hsp70), performing crucial biological functions within organisms. A comparative genome analysis of four genomes (Vitis vinifera, Eucalyptus grandis, Lagerstroemia indica, and Punica granatum) revealed that the DnaJ gene family in L. indica has undergone expansion, although not to the extent observed in P. granatum. Inter-genome collinearity analysis of four plants indicates that members belonging to Class A and B are more conserved during evolution. In L. indica, the expanded members primarily belong to Class-C. Tissue expression patterns and the biochemical characterization of LiDnaJs further suggested that DnaJs may be involved in numerous biological processes in L. indica. Transcriptome and qPCR analyses of salt stressed leaves identified at least ten LiDnaJs that responded to salt stress. In summary, we have elucidated the expansion mechanism of the LiDnaJs, which is attributed to a recent whole-genome triplication. This research laid the foundation for functional analysis of LiDnaJs and provides gene resources for breeding salt-tolerant varieties of L. indica.