Starch biosynthesis is a fundamental process influencing yield and fruit quality in banana, with ADP-glucose pyrophosphorylase (AGPase) serving as the rate-limiting enzyme catalyzing sucrose conversion into starch. However, the mechanisms underlying functional differentiation of AGPase family genes following polyploidization remain largely unexplored. In this study, eight AGPase genes, including large (MaAPL) and small subunit (MaAPS) members, were identified from the banana (Musa acuminata) genome, all harboring the conserved ADP-glucose pyrophosphorylase domain. Phylogenetic analysis traced their evolutionary origin to the ancient moss Physcomitrella patens, with polyploidization identified as the primary driver of gene family expansion. These genes exhibit conserved codon usage bias and have undergone strong purifying selection. Among them, MaAPS1 displayed distinct functional differentiation, increased intron number, enriched promoter cis-elements, and significantly elevated expression—features likely contributing to its adaptation for enhanced starch accumulation in fruit. Furthermore, the MaAPS1 protein was predominately localized in the chloroplast. Functional validation supported its regulatory involvement: transient silencing in banana fruit reduced starch content, while transient overexpression in banana fruit increased starch levels. Co-expression and molecular docking analyses revealed that transcription factors ERF1, C3H1, bZIP1, and bZIP3 may interact with the MaAPS1 promoter, indicating a multifactorial regulatory network. Overall, this study provides insights into polyploidy-driven functional innovation and transcriptional regulation of MaAPS1 in banana starch biosynthesis, providing valuable molecular targets for genetic improvement of yield and fruit quality.

Sisal ( Agave sisalana ) productivity is severely threatened by purple leaf roll and zebra stripe diseases. The SQUAMOSA PROMOTER BINDING PROTEIN (SBP)-box gene family is an important regulator of plant defense against biotic stresses, yet its role in sisal immunity remains poorly understood. We performed a genome-wide identification of AhSBP genes in the A. sisalana genome and analyzed their expansion mechanisms through phylogenetic and synteny modeling. Comparative transcriptomics, promoter cis-element analysis, and RT-qPCR validation were further integrated to elucidate the regulatory mechanisms of the miR156-AhSBP module under pathogen stress. A total of 45 AhSBP genes were identified, revealing a lineage-specific expansion mainly driven by segmental duplication (70%). Among these, 18 AhSBP genes were identified as putative miR156 targets. Transcriptomic and qPCR analyses showed that asi-miR156 is significantly induced in susceptible cultivars, leading to the suppression of its direct targets, such as AhSBP9 and AhSBP38 . In contrast, resistant cultivars maintain low miR156 levels, allowing the activation of the SBP-mediated defense program. Our findings suggest that the miR156-AhSBP module serves as a primary regulatory hub coordinating sisal's immune homeostasis, while members like AhSBP17 and AhSBP34 likely function as downstream effectors. This study provides a comprehensive understanding of the AhSBP gene family and offers potential genetic targets for engineering broad-spectrum disease resistance in sisal.