MaNAP1-MaMADS1 module orchestrates a hierarchical transcriptional network that mediates ethylene-regulated peel softening in banana
Banana (Musa spp.) peel undergoes rapid softening during ripening, leading to finger drop and a shortened shelf life. The regulatory mechanism behind this process remains to be elucidated. In this study, we confirmed the role of peel softening in banana finger drop and demonstrated the underlying transcriptional regulatory network. Cell wall modifying (CWM) genes were significantly upregulated in both banana peel and finger drop zone during ethylene-treated fruit ripening. Transcriptome and genome-wide profiling of chromatin accessibility and transcription factors (TFs) binding revealed that critical participants of fruit ripening, MaNAP1 and MaMADS1, regulate the CWM genes by directly binding to their promoters or by targeting other ripening-related TFs to form a hierarchical regulatory network. Notably, MaNAP1 and MaMADS1 were directly targeted by MaEIL4 and associated with tissue-specific histone modifications, enabling them to integrate MaEIL4-mediated ethylene signaling and undergo epigenetic regulation. Overexpression of MaNAP1, MaMADS1 or other newly identified regulatory TFs significantly upregulated the CWM genes and promoted peel softening. Our findings unveil a MaNAP1-MaMADS1 centered regulatory cascade governing banana peel softening and finger drop, thereby providing potential targets for improving banana texture and extending its shelf life.