MaNAC029 and MaNAC19 synergistically regulate ethylene and sucrose synthesis during banana fruit ripening

Ethylene is a critical phytohormone for climacteric fruits, such as banana, triggering the initiation of ripening and subsequent physiological and metabolic shifts, ultimately facilitating the formation of characteristic fruit quality attributes. NAC transcription factors (TFs) are crucial in ethylene-induced fruit ipening and quality formation. Our recent study revealed that MaNAC029 orchestrates ethylene biosynthesis during banana fruit ripening by directly transcriptionally modulating ethylene synthesis genes (MaACO1/13). Meanwhile, MaNAC19 regulates sucrose accumulation via activating the sucrose phosphate synthase gene (MaSPS1), but the functional interplay between MaNAC029 and MaNAC19 has not been elucidated. Herein, MaNAC029/19 were found to exhibit synchronized expression patterns during banana fruit ripening, with both genes significantly upregulated following ethylene production. Protein-protein interaction analysis manifested that MaNAC029 physically interacts with MaNAC19. Critically, MaNAC029 binds specifically to the MaSPS1 promoter, while MaNAC19 occupies promoters of MaACO1/13, indicating cross-regulation of each other's downstream targets. Notably, MaNAC029 and MaNAC19 synergistically activate the promoter activities of MaACO1/13 and MaSPS1. Collectively, these results establish the MaNAC029-MaNAC19 complex as a cooperative transcriptional module that integrates ethylene biosynthesis and sucrose metabolism, advancing our mechanistic understanding of the transcriptional networks governing banana fruit ripening and quality formation.