Spatiotemporal Modulation of Cell Wall, Sugar and Reactive Oxygen Species Metabolism Genes in Banana during Fruit Development and Ripening

Abstract

Understanding the spatiotemporal regulation of gene expression during fruit development and ripening is crucial for improving postharvest quality and shelf-life in climacteric fruits like banana. This study focused on differential expression of key metabolic genes involved in cell wall modification, reactive oxygen species, and sugar synthesis across different developmental and ripening stages in banana (cv. Grand Naine). Quantification of starch and total soluble sugars revealed dynamic changes in starch degradation and soluble sugar accumulation during early to late ripening stages.  In addition, sucrose, glucose and maltose emerging as the predominant sugar at late ripening stages. The RTq-PCR based gene expression demonstrated distinct spatiotemporal patterns, where xyloglucan endotransglucosylase/hydrolase gene family such as XTH3, XTH4, and XTH8 were highly expressed during early developmental stages, supporting cell expansion. Whereas, XTH5, XTH6, and PEL1 exhibited strong induction during ripening, indicating involvement of these genes in cell wall disassembly and softening. Superoxide dismutase exhibited increased expression during late ripening in pulp, suggesting reactive oxygen species scavenging role during degradation of cell wall components. Sucrose synthase gene expression reduced from developmental to ripening phase indicating carbon partitioning during fruit development. Collectively, the coordinated action of XTH -3, -4, -5, -6, -8, pectate lyase, superoxide dismutase, peroxidase, and sucrose synthase genes underscores their role in carbon partitioning and sugar metabolism, cell wall modification, and reactive oxygen species homeostasis during fruit development and ripening. This study provides a novel molecular insight governing banana fruit development and ripening. Information on modulation of genes provide foundation and open up the window for further validation, to assign their individual functional role in fruit development and ripening through genome editing tools.