BomMDH1 regulates malate-mediated oxidative stress in tobacco BY-2 suspension cells

Programmed cell death (PCD) is a genetically regulated process of cell suicide essential for plant development. The 'malate valve' is a mechanism that ensures redox balance across different subcellular compartments. In broccoli, the BomMDH1 gene encodes malate dehydrogenase in mitochondria, a critical enzyme in the 'malate circulation' pathway. This study investigates the functional role of BomMDH1 in malate (MA)-induced apoptosis in bright yellow-2 (BY-2) suspension cells. Findings revealed that transgenic cells overexpressing BomMDH1 showed enhanced viability under MA-induced oxidative stress compared to wild-type (WT) cells. Overexpression of BomMDH1 also reduced levels of reactive oxygen species (ROS), hydrogen peroxide (H2O2), and malondialdehyde (MDA), while increasing the expression of antioxidant enzyme genes such as NtAPX, NtAOX1a, NtSOD, and NtMDHAR. Additionally, treatment with salicylhydroxamic acid (SHAM), a characteristic inhibitor of mitochondrial respiration, further improved the anti-apoptotic activity of BY-2 cells. Overall, these results highlighted the function of the BomMDH1 gene and the potential of SHAM treatment in mitigating oxidative stress in BY-2 suspension cells.