Fig. 7
Description of sorghum orthologs across species and drought related GO terms. Key to legend: RWD = response to water deprivation; RH = response to heat and RABAS = response to ABA stimulus. The Venn-diagram shows patterns of shared sorghum orthologous gene clusters among its relative species and GO terms related to drought stress. a shows the distribution of shared sorghum orthologs among species, giving some clue on evolutionary implication and functional crosstalk of genes and on the extent of shared conserved syntheny among species related to sorghum. Closely related species (eg. maize and rice) share higher conserved sorghum orthologs (2549 genes) than relatively distantly related species to sorghum, for example maize and arabidopsis only share 367 sorghum orthologous genes and rice and arabidopsis share 194 sorghum orthologs. Surprisingly, 2098 sorghum orthologs shared among all the species seemingly represent ancestral gene families. All the genes in the diagram represent sorghum orthologs in the respective species. The non-shared ones indicate the unique sorghum orthologs found only in the corresponding species. b shows the pattern of distribution of genes involved in key selected drought related GO-terms. Functional overlapping was indicated as a clue for gene network among categories involved in complex stress responses with some genes playing a rate limiting role. For example, two genes ‘Sb09g026860.1’ and ‘Sb07g014940.1’ are shared and act in all the pathways. Pathway controlling response to water deprivation shares 40 overlapping genes with the one controlling response to ABA stimulus and six genes with the pathway regulating response to heat (Additional file 2: Table S12). Similarly, the pathway controlling response to ABA stimulus and that controls response to heat share six genes between them. On the other hand, 265 unique sorghum orthologs were identified in total for drought related responses with almost equal proportion of unique genes associated to each of the three Go-terms