Fruit ripening is a tightly regulated biological process that determines texture, flavor, color, and overall quality. In climacteric fruits such as banana, ripening is accompanied by rapid softening driven by the breakdown of cell wall polysaccharides. While enzymes like polygalacturonases and pectate lyases are known to mediate this process, the transcriptional mechanisms coordinating their expression remain incompletely understood. Excessive softening reduces transportability and causes significant postharvest losses, with up to half of harvested bananas affected annually. Although several transcription factors have been implicated in ripening, the upstream regulatory cascades controlling softening are still unclear. Based on these challenges, in-depth investigation into the transcriptional networks governing banana softening is urgently needed.
In a study published (DOI: 10.1093/hr/uhaf275) in Horticulture Research on February 6, 2026, researchers from the Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, identified MaMYB69 as a central regulator of banana fruit softening. The team demonstrated that this R2R3-type MYB transcription factor directly activates multiple cell wall–degrading genes and cooperates with other regulators to accelerate ripening. Their findings establish a transcriptional cascade linking MabZIP5, MaMYB69, and MaERF55, revealing a coordinated mechanism underlying banana fruit texture changes.
Using transcriptomic analysis of ripening banana fruit, the researchers first identified MaMYB69 as an ethylene-induced gene strongly upregulated during ripening. Subcellular localization and transactivation assays confirmed that MaMYB69 functions as a nuclear transcriptional activator. Dual-luciferase reporter assays and electrophoretic mobility shift assays showed that MaMYB69 directly binds to AC-box motifs in the promoters of key cell wall–modifying genes, including MaPE, MaPL1, MaGAL, and MaPG3, activating their transcription.
Functional validation was performed through overexpression experiments. In transgenic tomato, MaMYB69 accelerated color change, increased ethylene production, and reduced fruit firmness. Similarly, transient overexpression in banana enhanced softening and significantly elevated expression of downstream cell wall–degrading genes.
Mechanistically, the study revealed that MaMYB69 forms a homodimer and also interacts with MaERF55, an AP2/ERF family transcription factor. Their interaction strengthened activation of softening-related genes. Upstream, MabZIP5, previously known as an aroma biosynthesis regulator, directly binds to the MaMYB69 promoter and activates its transcription. Together, these findings uncover a multilayered transcriptional cascade in which MabZIP5 activates MaMYB69, which in turn recruits MaERF55 to amplify cell wall degradation during ripening.
“This work uncovers a central transcriptional hub that integrates ethylene signaling, aroma-related regulation, and cell wall disassembly,” the corresponding authors noted. “By identifying MaMYB69 as a positive regulator of fruit softening and mapping its upstream and downstream partners, we provide new insights into the regulatory logic of banana ripening. The cooperative interaction between MYB and ERF transcription factors highlights how multiple regulators converge to fine-tune fruit texture.”
Understanding the genetic control of fruit softening is essential for improving postharvest management and reducing global food waste. By identifying MaMYB69 as a pivotal regulator of cell wall degradation, this study provides potential molecular targets for breeding or biotechnological strategies aimed at delaying softening without compromising flavor development. Manipulating components of the MabZIP5–MaMYB69–MaERF55 cascade could allow more precise control over ripening speed, extending shelf life and enhancing transport resilience. Beyond banana, these findings also enrich the broader understanding of transcriptional networks governing climacteric fruit ripening and may inform improvement strategies in other commercially important crops.
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References
DOI
10.1093/hr/uhaf275
Original Source URL
https://doi.org/10.1093/hr/uhaf275
Funding information
This work received financial support from the Natural Science Foundation of China (32172544, 65032261160375), the special fund for scientific innovation strategy-construction of high level 651Academy of Agriculture Science (R2023PY-JG003), the earmarked fund for CARS (CARS-31-65201), Guangdong Special Support Program (NYLJ2024010), and IAEA CRP D23033.
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2023. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.