UBC18 mediates ERF1 degradation under light-dark cycles

Area of Science:

• Plant Molecular Biology
• Stress Physiology
• Biochemistry

Background:

• Ethylene Response Factor 1 (ERF1) is a key regulator of plant responses to biotic and abiotic stresses.
• ERF1's instability in darkness and role in hypocotyl elongation are known, but its degradation mechanism remains unclear.

Purpose of the Study:

• To elucidate the molecular mechanism controlling Ethylene Response Factor 1 (ERF1) protein degradation.
• To identify proteins interacting with ERF1 and mediating its stability.

Main Methods:

• Yeast two-hybrid screening to identify ERF1 interacting proteins.
• Pull-down assays and co-immunoprecipitation to confirm ERF1-UBC18 interaction.
• Analysis of ERF1 protein abundance in UBC18 mutant and overexpression lines.
• In vivo ubiquitination assays to assess ERF1 ubiquitination.

Main Results:

• Ubiqutin-conjugating enzyme 18 (UBC18) was identified as an ERF1-interacting protein.
• UBC18 mediates the ubiquitination and subsequent 26S proteasome-dependent degradation of ERF1.
• ERF1 protein is more stable in UBC18 mutants and less stable in UBC18 overexpression lines.
• UBC18 negatively regulates drought and salt stress responses by modulating ERF1 abundance.

Conclusions:

• UBC18 acts as a negative regulator of ERF1 stability and function.
• The UBC18-mediated ERF1 degradation pathway is crucial for regulating plant adaptation to environmental stresses and dark-induced growth processes.