Isolation, structure analysis and expression characterization of the Hexokinase gene family in Sorghum bicolor

Hexokinases (HXK) not only facilitate carbohydrate metabolism but also play important roles in sugar sensing in higher plants. HXK gene families have been extensively discussed in many plant species; however, comprehensive information regarding HXKs in sorghum remains unclear. To address this gap, we identified 7 putative sorghum HXKs (SbHXK1 to SbHXK7), and the features of their conserved domains, gene structure, evolutionary tree, and cis-acting elements were systematically characterized to reveal the evolutionary conservation between different plant species. Based on expression profiling, we found that different expression patterns of SbHXKs were associated with different physiological processes, including abiotic stresses. Further qRT-PCR verification under salt and sucrose treatment confirmed that SbHXK2, SbHXK4, and SbHXK5 may play very important roles under high osmotic pressure. Notably, SbHXKs are predominantly localized in the cytoplasm, in contrast to some rice and Arabidopsis HXKs, which are localized in chloroplasts or mitochondria, suggesting divergent roles for SbHXKs. In summary, our study provides a theoretical foundation for understanding the HXK gene family and offers fundamental insights of SbHXKs in sorghum.