The rapid production of hydrogen peroxide (H₂O₂) is a hallmark of plants’ successful recognition of pathogen infection and plays a crucial role in innate immune signaling. Aquaporins (AQPs) are membrane channels that facilitate the transport of small molecular compounds across cell membranes. In plants, AQPs from the plasma membrane intrinsic protein (PIP) family are utilized for the transport of H₂O₂, thereby regulating various biological processes. Plants contain two PIP families, PIP1s and PIP2s. However, the specific functions and relationships between these subfamilies in plant growth and immunity remain largely unknown. In this study, we explore the synergistic role of AtPIP1;4 and AtPIP2;4 in regulating plant growth and disease resistance in Arabidopsis. We found that in plant cells treated with H₂O₂, AtPIP1;4 and AtPIP2;4 act as facilitators of H₂O₂ across membranes and the translocation of externally applied H₂O₂ from the apoplast to the cytoplasm. Moreover, AtPIP1;4 and AtPIP2;4 collaborate to transport bacterial pathogens and flg22-induced apoplastic H₂O₂ into the cytoplasm, leading to increased callose deposition and enhanced defense gene expression to strengthen immunity. These findings suggest that AtPIP1;4 and AtPIP2;4 cooperatively mediate H₂O₂ transport to regulate plant growth and immunity.

Fusarium graminearum is recognized as the pathogen responsible for wheat head blight. It produces deoxynivalenol (DON) during infection, which endangers human health. DON biosynthesis occurs within toxisomes in the endoplasmic reticulum (ER). In eukaryotes, the ER membrane protein complex (EMC) is critical for the ER’s normal operation. However, the specific role of the EMC in F. graminearum remains poorly understood. In this study, six EMC subunits (FgEmc1-6) were identified in F. graminearum, and all of them were localized to the toxisomes. Our results demonstrate that the EMC is indispensable for vegetative growth and asexual and sexual reproduction, which are the fundamental life processes of F. graminearum. Importantly, EMC deletion led to reduced virulence in wheat spikes and petioles. Further investigation revealed that in ΔFgemc1-6, the expression of trichothecene (TRI) genes is decreased, the biosynthesis of lipid droplets (LDs) is diminished, toxisome formation is impaired, and DON production is reduced. Additionally, defects in the formation of the infection cushion were observed in ΔFgemc1-6. In conclusion, the EMC is involved in regulating growth and virulence in F. graminearum. This study enhances our understanding of the EMC functions in F. graminearum and offers valuable insights into potential targets for managing wheat head blight.