The F-box protein RhSAF destabilizes the gibberellic acid receptor RhGID1 to mediate ethylene-induced petal senescence in rose

Abstract

Roses are among the most popular ornamental plants cultivated worldwide for their great economic, symbolic, and cultural importance. Nevertheless, rapid petal senescence markedly reduces rose (Rosa hybrida) flower quality and value. Petal senescence is a developmental process tightly regulated by various phytohormones. Ethylene accelerates petal senescence, while gibberellic acid (GA) delays this process. However, the molecular mechanisms underlying the crosstalk between these phytohormones in the regulation of petal senescence remain largely unclear. Here, we identified SENESCENCE-ASSOCIATED F-BOX (RhSAF), an ethylene-induced F-box protein gene encoding a recognition subunit of the SCF-type E3 ligase. We demonstrated that RhSAF promotes degradation of the GA receptor GIBBERELLIN INSENSITIVE DWARF1 (RhGID1) to accelerate petal senescence. Silencing RhSAF expression delays petal senescence, while suppressing RhGID1 expression accelerates petal senescence. RhSAF physically interacts with RhGID1s and targets them for ubiquitin/26S proteasome-mediated degradation. Accordingly, ethylene-induced RhGID1C degradation and RhDELLA3 accumulation are compromised in RhSAF-RNAi lines. Our results demonstrate that ethylene antagonizes GA activity through RhGID1 degradation mediated by the E3 ligase RhSAF. These findings enhance our understanding of the phytohormone crosstalk regulating petal senescence and provide insights for improving flower longevity.