Background: Sorghum, the C4 dry-land cereal, important for food, fodder, feed and fuel,
is a model crop for abiotic stress tolerance with smaller genome size, genetic diversity, and bioenergy
traits. The heat shock proteins/chaperonin 60s (HSP60/Cpn60s) assist the plastid proteins,
and participate in the folding and aggregation of proteins. However, the functions of HSP60s in abiotic
stress tolerance in Sorghum remain unclear.
Methods: Genome-wide screening and in silico characterization of SbHSP60s were carried out
along with tissue and stress-specific expression analysis.
Results: A total of 36 HSP60 genes were identified in Sorghum bicolor. They were subdivided into
2 groups, the HSP60 and HSP10 co-chaperonins encoded by 30 and 6 genes, respectively. The
genes are distributed on all the chromosomes, chromosome 1 being the hot spot with 9 genes. All
the HSP60s were found hydrophilic and highly unstable. The HSP60 genes showed a large number
of introns, the majority of them with more than 10. Among the 12 paralogs, only 1 was tandem and
the remaining 11 segmental, indicating their role in the expansion of SbHSP60s. Majority of the
SbHSP60 genes expressed uniformly in leaf while a moderate expression was observed in the root
tissues, with the highest expression displayed by SbHSP60-1. From expression analysis, SbHSP60-
3 for drought, SbHSP60-9 for salt, SbHSP60-9 and 24 for heat and SbHSP60-3, 9 and SbHSP10-
2 have been found implicated for cold stress tolerance and appeared as the key regulatory
Conclusion: This work paves the way for the utilization of chaperonin family genes for achieving
abiotic stress tolerance in plants.