Genome-wide identification of maize G protein genes and regulatory roles of the ZmGG1 subfamily in saline-alkali stress response.

Saline-alkaline stress is a major constraint in maize (Zea mays L.) production. Heterotrimeric G proteins play pivotal roles in plant stress responses. However, their functional mechanisms in maize under saline-alkaline stress remain poorly understood. This study aimed to characterize the maize G protein gene family and elucidate its regulatory mechanisms in response to saline-alkaline stress. Ten G protein genes (belonging to the Gα, Gβ, and Gγ subunit families) were identified from the maize genome using bioinformatics approaches. Their phylogenetic relationships, gene structures, promoter cis-acting elements, and protein-protein interaction (PPI) networks were systematically analyzed. Gene expression patterns in the saline-alkaline tolerant inbred line Zheng58 and the sensitive line Chang7-2 were investigated using qRT-PCR, alongside the determination of reactive oxygen species (ROS)-scavenging enzyme activities. The Gγ subfamily members (ZmGG1, ZmGG3, and ZmGG5) exhibited differential expression patterns. PPI network analysis revealed extensive interactions between G proteins and signaling components such as phospholipase C and MAP kinases. Under stress conditions, Chang7-2 displayed significant fluctuations in ROS-scavenging enzyme activity and accumulation of malondialdehyde (MDA). Therefore, this study elucidated the mechanism by which maize G proteins coordinate saline-alkaline stress responses through subfamily-specific expression regulation and intricate signaling networks, thereby providing potential candidate target genes for breeding stress-tolerant maize.