FvIAA16 and FvIAA17: Two Aux/IAA Family Genes Positively Regulate Fruit Ripening in Strawberry

Aux/IAA genes, functioning as transcriptional regulators downstream of auxin signaling, are essential for plant growth and development. However, their roles in fruit ripening remain largely undefined in strawberry. This study aims to elucidate the role of Aux/IAA genes in strawberry ripening. We identified 22 Aux/IAA family members and performed comprehensive spatiotemporal expression and hormone response analyses. Among them, FvIAA16 and FvIAA17 emerged as strong candidates associated with fruit ripening. Transient overexpression of FvIAA16 and FvIAA17 upregulated the expression of multiple ripening-related genes, leading to anthocyanin accumulation, soluble sugar enrichment, organic acid homeostasis, and furanone production. Dual-luciferase assays further demonstrated that both proteins robustly activated the promoters of ripening-related genes such as FvCHI and FvCHS. This activation was further enhanced by dimerization of the two proteins. Collectively, these findings reveal important regulatory functions of FvIAA16 and FvIAA17 in strawberry fruit ripening and offer valuable clues for further elucidating the molecular mechanisms underlying auxin-mediated ripening regulation.