Synthetically derived BiAux modulates auxin co-receptor activity to stimulate lateral root formation

Area of Science:

• Plant Biology
• Molecular Biology
• Developmental Biology

Background:

• Root development is crucial for plant growth and environmental adaptation.
• Lateral root formation is a clock-driven process regulated by auxin signaling.
• The precise assembly of auxin co-receptors remains poorly understood.

Purpose of the Study:

• To identify compounds that specifically regulate lateral root formation.
• To elucidate the mechanism by which auxin co-receptors assemble and function.
• To investigate the role of BiAux in modulating auxin signaling for lateral root development.

Main Methods:

• Identification and characterization of the compound bis-methyl auxin conjugated with N-glucoside (BiAux) in Arabidopsis.
• Docking analyses to predict BiAux binding to F-box proteins.
• Functional analysis of BiAux in Arabidopsis, including dependence on TIR1, AFB2, and ARF7.
• Heterologous expression in yeast (Saccharomyces cerevisiae) to study co-receptor subunit assemblage and protein degradation.

Main Results:

• BiAux specifically induces lateral root prebranch sites (PBS) and lateral root (LR) emergence with minimal effect on root elongation.
• BiAux binds to F-box proteins and its function is dependent on TIR1 and AFB2 F-box proteins, and AUXIN RESPONSE FACTOR 7.
• BiAux promotes the assembly of specific auxin co-receptor subunits and enhances AUXIN/INDOLE-3-ACETIC ACID 28 degradation in yeast.

Conclusions:

• BiAux acts as an allosteric modulator of specific auxin co-receptors.
• BiAux provides fine-tuned regulation of auxin signaling for targeted lateral root formation.
• This study clarifies the assembly of auxin co-receptors and offers a tool for manipulating root development.