The ubiquitin-26S proteasome system provides a key mechanism for regulating protein turnover in plants and contributes to the control of diverse developmental and stress-related processes. Within this system, Skp1-Cullin1-F-box (SCF) E3 ligases rely on F-box proteins to confer substrate specificity, enabling selective and dynamic regulation of target protein stability. The large size and structural diversity of the F-box protein family in plants suggest extensive functional specialization, although many members remain poorly characterized. Here, we review recent advances in the understanding of F-box protein function, with a focus on their roles in plant development, stress adaptation, and immunity. Specifically, this review integrates findings across development, abiotic stresses, and immunity to highlight shared and diverging regulatory nodes and critically assesses the strength of substrate evidence to distinguish bona fide from putative F-box targets. We highlight how F-box proteins modulate key regulatory pathways, including phytohormone signaling, reproductive development, root architecture, and secondary metabolism, as well as responses to abiotic and biotic stresses. Emerging evidence indicates that F-box-mediated proteolysis acts as an important layer of control linking environmental signals to downstream transcriptional and physiological outputs. A better understanding of F-box protein substrates and regulatory networks is important for dissecting plant adaptive mechanisms and may provide molecular targets for future crop improvement strategies.
Zhong et al. (Tue,) studied this question.