Analysis of the sorghum RBOH gene family and molecular mechanism of its member SbRBOHG in response to aluminum stress

Respiratory Burst Oxidase Homologs (RBOHs) serve as core regulatory components in plant responses to abiotic stress, with their mediated reactive oxygen species (ROS) signaling playing a crucial role in plant adaptation to environmental challenges. This study identified 10 SbRBOH genes distributed across seven chromosomes in the sorghum (Sorghum bicolor L.) genome. Phylogenetic analysis revealed species-specific evolution within this gene family. Expression pattern analysis showed significantly higher SbRBOHG expression in root tissues, suggesting its potential involvement in root stress responses. Multiple sequence alignment and structural modeling revealed that SbRBOHG shares 64.79% amino acid sequence identity with Arabidopsis AtRBOHD, with highly conserved three-dimensional conformation. Functional studies demonstrated that heterologous overexpression of SbRBOHG in Arabidopsis enhanced plant tolerance to aluminum stress, accompanied by increased ROS accumulation in roots. Protein interaction assays (yeast two hybrid and bimolecular fluorescence complementation) further confirmed direct interaction between SbRBOHG and the kinase SbBIK1. RT-qPCR analysis also showed that Arabidopsis plants heterologously overexpressing the SbRBOHG gene activate the expression of AtSTOP1, a key regulator of aluminum stress, and its downstream anion channel gene, AtALMT1. These studies have preliminarily established the functional role of the SbRBOHG gene in aluminum toxicity in sorghum. The research has elucidated the physical interactions between SbBIK1 and SbRBOHG at the molecular level, providing a theoretical basis and candidate gene resources for the genetic improvement of aluminum-tolerant sorghum varieties.