Wheat SLC25A4-7B negatively regulates drought tolerance by coordinating stomatal aperture size and abscisic acid...

TaSLC25A4-7B is closely related to the biological processes involved in drought stress and the ABA signaling pathway through the regulation of stomata, providing a theoretical basis for exploring drought resistance in wheat. The solute carrier family 25 (SLC25) member SLC25A4 plays important roles in plant growth regulation. However, its roles in drought-stress response remain unclear. Here, we determined that the mitochondrial wheat (Triticum aestivum L.) SLC25A4-7B gene (TaSLC25A4-7B) was involved in regulating drought responses by coordinating stomatal aperture and abscisic acid (ABA). Tobacco and rice plants overexpressing TaSLC25A4-7B (OxTaSLC25A4-7B) showed increased stomatal aperture and/or size, as well as impaired drought tolerance. The larger stomata were associated with altered stomatal morphology, downregulated ABA synthesis-related genes and upregulated ABA degradation-related genes. Consistently, the endogenous ABA contents were markedly altered in tobacco OxTaSLC25A4-7B compared with wild type. Additionally, the larger stomata were associated with a higher photosynthetic capacity in rice OxTaSLC25A4-7B compared with Nipponbare. Under drought conditions, the OxTaSLC25A4-7B transgenic plants showed severe wilting phenotypes and increased contents of reactive oxygen species and malondialdehyde compared with the control. Furthermore, we found that wheat protein phosphatase type 2C binds to the promoter of TaSLC25A4-7B and inhibits the gene's activity. The results suggested that TaSLC25A4-7B negatively regulated drought tolerance.