Genome-wide identification and expression profile analysis of trihelix transcription factor family genes in response to abiotic stress in sorghum [Sorghum bicolor (L.) Moench]

BackgroundTranscription factors, including trihelix transcription factors, play vital roles in various growth and developmental processes and in abiotic stress responses in plants. Thetrihelixgene has been systematically studied in some dicots and monocots, includingArabidopsis,tomato, chrysanthemum, soybean, wheat, corn, rice, and buckwheat. However, there are no related studies on sorghum.ResultsIn this study, a total of 40 sorghum trihelix (SbTH) genes were identified based on the sorghum genome, among which 34 were located in the nucleus, 5 in the chloroplast, 1 (SbTH38) in the cytoplasm, and 1 (SbTH23) in the extracellular membrane. Phylogenetic analysis of theSbTHgenes andArabidopsisand ricetrihelixgenes indicated that the genes were clustered into seven subfamilies: SIP1, GTγ, GT1, GT2, SH4, GTSb8, and orphan genes. TheSbTHgenes were located in nine chromosomes and none on chromosome 10. One pair of tandem duplication gene and seven pairs of segmental duplication genes were identified in theSbTHgene family. By qPCR, the expression of 14 SbTH members in different plant tissues and in plants exposed to six abiotic stresses at the seedling stage were quantified. Except for the leaves in which the genes were upregulated after only 2 h exposure to high temperature, the 12 SbTHgenes were significantly upregulated in the stems of sorghum seedlings after 24 h under the other abiotic stress conditions. Among the selected genes,SbTH10/37/39were significantly upregulated, whereasSbTH32was significantly downregulated under different stress conditions.ConclusionsIn this study, we identified 40 trihelix genes in sorghum and found that gene duplication was the main force drivingtrihelixgene evolution in sorghum. The findings of our study serve as a basis for further investigation of the functions ofSbTHgenes and providing candidate genes for stress-resistant sorghum breeding programmes and increasing sorghum yield.