Ethylene Biosynthesis Regulation and Ripening Gene Expression in Banana (Musa acuminata) Cultivars of the Niger Delta: Implications for Post-Harvest Management

Banana ripening is governed by ethylene biosynthesis and perception pathways that regulate the expression of ripening-associated genes controlling starch-to-sugar conversion, cell wall degradation, and aroma development. In the Niger Delta region of South South Nigeria, where banana production forms a significant rural livelihood activity, the molecular basis of ripening in locally dominant Musa acuminata cultivars has never been characterized. This dissertation investigates ethylene biosynthesis gene expression profiles, ethylene evolution rates, and ripening-associated gene regulation in three dominant Niger Delta banana cultivars during post-harvest ripening under ambient and modified atmosphere conditions. Gene expression analysis using RT-qPCR was performed for key ethylene pathway genes including MaACS1, MaACO1, MaERF, and downstream ripening regulators at 24-hour intervals over a 10-day post-harvest period. Metabolomics profiling of soluble sugars, organic acids, and aroma volatiles was integrated with gene expression data using time-resolved correlation analysis. Results reveal cultivar-specific differences in the timing and magnitude of ethylene burst, associated with differential expression of MaACO1 and divergent downstream ripening gene networks. Modified atmosphere treatment with 5% CO2 suppressed ethylene evolution and ripening gene expression by 40 to 60 percent. The study provides the first molecular post-harvest dataset for Niger Delta banana cultivars, establishing mechanistic targets for biotechnology-assisted shelf life extension. Keywords: banana, ethylene biosynthesis, ripening genes, post-harvest, Niger Delta