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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 of Sorghum bicolor revealed 113 DnaJ/Hsp40 genes, classified into four groups; 8 genes in SbDnaJ-A class, 10 in SbDnaJ-B, 82 in SbDnaJ-C and 13 in SbDnaJ-D distributed 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 the SbDnaJ-C which 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 of SbDnaJ-C76. The SbDnaJ-A1, D1, and C subgroup genes displayed upregulation in roots, stems and leaves under cold, inferring the involvement of Hsp40s for cellular protection during cold stress. The results demonstrate that C76 and D1 are the candidate genes associated with multiple abiotic stresses. Present research furnishes valuable information about the role of sorghum DnaJs in abiotic stress response and establishes a foundation for understanding the molecular mechanisms associated with plant development and stress tolerance.

The small heat shock proteins (sHsps/Hsp20s) are the molecular chaperones that maintain proper folding, trafficking and disaggregation of proteins under diverse abiotic stress conditions. In the present investigation, a genome-wide scan revealed the presence of a total of 47 sHsps in Sorghum bicolor (SbsHsps), distributed across 10 subfamilies, the major subfamily being P (plastid) group with 17 genes. Chromosomes 1 and 3 appear as the hot spot regions for SbsHsps, and majority of them were found acidic, hydrophilic, unstable and intron less. Interestingly, promoter analysis indicated that they are associated with both biotic and abiotic stresses, as well as plant development. Sorghum sHsps exhibited 15 paralogous and 20 orthologous duplications. Expression analysis of 15 genes selected from different subfamilies showed high transcript levels in roots and leaves implying that they are likely to participate in the developmental processes. SbsHsp genes were highly induced by diverse abiotic stresses inferring their critical role in mediating the environmental stress responses. Gene expression data revealed that SbsHsp-02 is a candidate gene expressed in all the tissues under varied stress conditions tested. Our results contribute to the understanding of the complexity of SbsHsp genes and help to analyse them further for functional validation., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Members of the plant Heme Activator Protein (HAP) or NUCLEAR FACTOR Y (NF-Y) are trimeric transcription factor complexes composed of the NF-YA, NF-YB and NF-YC subfamilies. They bind to the CCAAT box in the promoter regions of the target genes and regulate gene expressions. Plant NF-Ys were reported to be involved in adaptation to several abiotic stresses as well as in development. In silico analysis of Sorghum bicolor genome resulted in the identification of a total of 42 NF-Y genes, among which 8 code for the SbNF-YA, 19 for SbNF-YB and 15 for the SbNF-YC subunits. Analysis was also performed to characterize gene structures, chromosomal distribution, duplication status, protein subcellular localizations, conserved motifs, ancestral protein sequences, miRNAs and phylogenetic tree construction. Phylogenetic relationships and ortholog predictions displayed that sorghum has additional NF-YB genes with unknown functions in comparison with Arabidopsis. Analysis of promoters revealed that they harbour many stress-related cis-elements like ABRE and HSE, but surprisingly, DRE and MYB elements were not detected in any of the subfamilies. SbNF-YA1, 2, and 6 were found upregulated under 200 mM salt and 200 mM mannitol stresses. While NF-YA7 appeared associated with high temperature (40°C) stress, NF-YA8 was triggered by both cold (4°C) and high temperature stresses. Among NF-YB genes, 7, 12, 15, and 16 were induced under multiple stress conditions such as salt, mannitol, ABA, cold and high temperatures. Likewise, NF-YC 6, 11, 12, 14, and 15 were enhanced significantly in a tissue specific manner under multiple abiotic stress conditions. Majority of the mannitol (drought)-inducible genes were also induced by salt, high temperature stresses and ABA. Few of the high temperature stress-induced genes are also induced by cold stress (NF-YA2, 4, 6, 8, NF-YB2, 7, 10, 11, 12, 14, 16, 17, NF-YC4, 6, 12, and 13) thus suggesting a cross talk among them. This work paves the way for investigating the roles of diverse sorghum NF-Y proteins during abiotic stress responses and provides an insight into the evolution of diverse NF-Y members., Competing Interests: RP is the President & CEO of Genomix Molecular Diagnostics Pvt Ltd., Kukatpally, Hyderabad, India. RP is the CEO of Genomix CARL Pvt. Ltd., Andhra Pradesh, India, but does not receive a salary in this capacity. RP is the President and CEO of Genomix Biotech Inc., 2620 Braithwood Road, Atlanta, GA 30345, USA, but does not receive any salary in this capacity. There are no patents, or products in development or marketed products associated with this research to declare. This does not alter our adherence to PLOS ONE policies on sharing data and materials.