DnaJs, the critical drivers of Hsp70s: genome-wide screening, characterization and expression ofDnaJfamily genes in Sorghum bicolor

The DnaJ/Hsp40s, are important components in the chaperone machine, and play pivotal roles in plant growth, development and stress tolerance.Sorghum, the semi-arid crop, is the drought resilient, model C(4)crop. However, no reports of DnaJs have been available. Genome-wide analysis ofSorghum bicolorrevealed 113 DnaJ/Hsp40 genes, classified into four groups; 8 genes inSbDnaJ-Aclass, 10 inSbDnaJ-B, 82 inSbDnaJ-Cand 13 inSbDnaJ-Ddistributed unevenly on all the 10 chromosomes. Chromosomes 1 and 3 were found hot spots with 22 and 20 genes respectively. All genes displayed large number of introns, with an exception of 11 of theSbDnaJ-Cwhich is devoid of introns. Out of 36 paralogous duplications, 7 tandem and 29 segmental duplications were noticed, indicating the major role of segmental duplications in the expansion. Analysis of digital data revealed tissue and stage-specific expressions. Transcriptional profiling of 12 selected genes representing all 4 classes revealed highly significant expression in leaf followed by root tissues. No expression was noticed in stems with an exception ofSbDnaJ-C76. TheSbDnaJ-A1,D1, andCsubgroup genes displayed upregulation in roots, stems and leaves under cold, inferring the involvement of Hsp40s for cellular protection during cold stress. The results demonstrate thatC76andD1are the candidate genes associated with multiple abiotic stresses. Present research furnishes valuable information about the role of sorghumDnaJs in abiotic stress response and establishes a foundation for understanding the molecular mechanisms associated with plant development and stress tolerance.