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Silencing microRNA172 delays fruit ripening in apple (Malus domestica) through an AP2-ERF transcriptional regulation mechanism

Year: 2025

Type: article

Abstract: MicroRNA172 ( miR172 ) regulates many processes of plant development, including flowering and fruit growth, yet its function in fruit ripening remains unclear. In this study, we demonstrate that silencing miR172 in apple ( Malus domestica ) delays fruit ripening, which correlates with a postponed onset of climacteric ethylene production. At harvest, miR172 -silenced fruit displayed lower respiration rates than wild-type (WT) fruit, although these rates re-aligned with WT after 12 weeks of cool storage. Although at harvest miR172 -silenced and WT fruit showed similar firmness and levels of soluble solid content, the miR172 -silenced fruit maintained greater firmness and a higher level of soluble solid content (SSC) after 12 weeks of post-harvest storage at 0 °C. Comparative transcriptome analysis revealed these phenotypic changes to be associated with increased expression of APETALA2 ( AP2 ) homologs MdAP2_1b/2a ( miR172 target genes) and an Ethylene Response Factor ( ERF ) MdERF4 , along with reduced expression of ethylene biosynthesis genes MdACS1/ACO1 . In a dual luciferase reporter assay, MdAP2_1a/2a activated the MdERF4 promotor in tobacco leaves. These findings, together with existing knowledge that MdERF4 inhibits MdACS1/ACO1 expression, suggest a novel genetic regulatory network involving miR172 , MdAP2 and MdERF4 in controlling apple fruit ripening. • Stable transgenic apple plants were developed using a construct to silence miR172. • These transgenic plants exhibited delayed ethylene production in fruit, leading to postponed ripening. • During storage, transgenic fruits maintained higher firmness and sugar content compared to wild-type fruits. • The observed phenotype was regulated by the miR172–MdAP2–MdERF4 signalling module.

Source: Plant Science

DOI: 10.1016/j.plantsci.2025.112719