ScNF-YC2, a protein interacting with ScABI3, is a transcription factor regulating abiotic stress response in Syntrichia caninervis

The Nuclear Factor Y (NF-Y) transcription factor family plays a crucial role in plant abiotic stress responses. However, its function in Syntrichia caninervis , a desiccation-tolerant desert moss and an ideal model organism for investigating plant stress response mechanisms, remains poorly understood. In this study, we identified ScNF-YC2, a member of the NF-Y family, as a potential interacting partner of ScABI3, a key regulator of the abscisic acid (ABA) signaling pathway. Through yeast two-hybrid (Y2H), pull-down, and bimolecular fluorescence complementation (BiFC) assays, we confirmed the physical interaction between ScNF-YC2 and ScABI3 in the nucleus. Further analysis revealed that ScNF-YC2 is relatively conserved and is significantly induced under drought, salt, and ABA treatments. Overexpression of ScNF-YC2 in Arabidopsis thaliana and S. caninervis exacerbated the sensitivity to salt and drought stress by elevating reactive oxygen species (ROS) accumulation and suppressing antioxidant enzyme activity. Conversely, ScNF-YC2 overexpression partly reduced sensitivity to ABA in these plant species. These findings suggest that ScNF-YC2 plays a critical role in regulating abiotic stress responses in S. caninervis through its interaction with ScABI3, by modulating ROS homeostasis. Thus, the study highlights the subtle role of NF-Y transcription factors in regulating stress responses in desert moss. • Discovery of the ScNF-YC2-ScABI3 interaction: A nuclear-localized physical interaction between ScNF-YC2 (an NF-Y family member) and ScABI3 (a regulator of the ABA signaling pathway) was experimentally confirmed in Syntrichia caninervis , linking NF-Y transcription factors to ABA-mediated stress response pathways. • Dual role of ScNF-YC2 in stress sensitivity: Overexpression of ScNF-YC2 increased plant sensitivity to salt and drought stress by elevating reactive oxygen species (ROS) accumulation and suppressing antioxidant enzyme activity, while partially reducing ABA responsiveness. • ROS homeostasis as a regulatory mechanism: ScNF-YC2 modulates abiotic stress adaptation in the desert moss S. caninervis by regulating ROS homeostasis, uncovering a non-canonical role of NF-Y transcription factors in bryophyte stress tolerance.