An AsCtf1β-associated regulatory network contributes to fungal infection adaptation and shoot blight development in hybrid bamboo

Hybrid bamboo ( Bambusa pervariabilis × grandis ) is an important renewable feedstock for papermaking and bamboo-based products, but its sustainable production is constrained by shoot blight caused by Apiospora sphaerosperma . Disease development is accompanied by changes in redox status, cell-wall-associated defence and hormone-related responses in bamboo tissues, whereas the fungal regulatory processes that support adaptation to this host environment remain poorly understood. Here, we investigated an AsCtf1β-associated network involving promoter-associated regulation and protein interactions by combining promoter-associated and protein-interaction screening with molecular validation and functional analyses. Pairwise assays identified AsFSTF1, AsFSTF2 and AsAcu15 as promoter-associated candidates, with dual-luciferase and ChIP-qPCR analyses providing additional support for AsFSTF2 and AsAcu15, while Y2H, quantitative α-galactosidase assays and bimolecular fluorescence complementation supported interactions of AsCtf1β with AsCtf1α, AsCGBP, AsCGBF and AsTFB2. Selected candidates showed infection-associated transcriptional induction or increased protein accumulation. Deletion of representative genes altered AsCtf1β transcript abundance and impaired oxidative-stress tolerance, cell-wall and membrane integrity, carbon-source utilisation and asexual development, together with reduced fungal colonisation and lesion expansion. Mutant-inoculated bamboo tissues also showed lower H₂O₂ accumulation, callose deposition, defence-related enzyme activities, and jasmonic acid and salicylic acid contents. These host-side changes were associated with reduced fungal infection capacity rather than indicating direct regulation of bamboo immunity. Collectively, the AsCtf1β-associated network links fungal environmental adaptation with shoot blight development and local host defence-associated outputs, providing a mechanistic basis for identifying disease-management targets relevant to sustainable industrial bamboo production.