Mechanisms of Programmed Cell Death during Lysigenous Aerenchyma Formation in Plants under Waterlogging Stress

With the global warming, the frequency of extreme weather events such as flooding has been increasing, severely limiting plant growth. The essence of waterlogging stress is soil hypoxia, which restricts plant respiration and ultimately leads to plant death. To adapt to hypoxia stress, some plants develop adaptive structures such as aerenchyma to facilitate oxygen acquisition and maintain energy supply for growth. The formation of this structure fundamentally depends on programmed cell death (PCD) in cortical cells. Ethylene serves as a key initiating signal regulating aerenchyma formation. Under hypoxic conditions, it rapidly accumulates and induces the production of reactive oxygen species (ROS), thereby triggering the PCD process. During aerenchyma formation, group VII ethylene response factors (ERF-VII) function as central transcriptional hubs for hypoxia sensing and signal integration, coordinating ethylene, auxin, and other hormonal pathways to regulate the spatiotemporal pattern of PCD. Auxin transport and signaling pathways participate in aerenchyma formation by modulating the spatial distribution of cell death, while hormones such as abscisic acid, gibberellins, and cytokinins regulate this process through synergistic or antagonistic interactions. This review summarizes the cytological characteristics of PCD and the associated hormonal regulatory network during lysigenous aerenchyma formation under flooding stress, with particular emphasis on the pivotal roles of ethylene-ROS signaling and ERF-VII. It aims to provide a theoretical basis for elucidating plant flooding tolerance mechanisms and for the molecular improvement of flood-resistant crops.