Ethylene Response Factors in Plant Stress Adaptation: Regulatory Mechanisms and Opportunities for Crop Improvement

Ethylene response factor (ERF) proteins constitute a major branch of the AP2/ERF transcription factor superfamily and are conventionally divided into six groups (B1–B6) on the basis of conserved sequences and phylogenetic relationships. ERFs recognize cis-elements such as the GCC-box and dehydration-responsive element/C-repeat and assemble regulatory complexes with coactivators or corepressors. They thereby coordinate responses to drought, salinity, low and high temperatures, hypoxia, flooding, and pathogen attack. Their outputs are determined not by a single motif but by DNA-binding preference, interacting partners, tissue context, and post-translational control through mitogen-activated protein kinase phosphorylation, ubiquitination, and the N-degron pathway. Crop studies increasingly show that ERF alleles and regulatory modules can improve stress tolerance and disease resistance, although constitutive manipulation frequently compromises growth, yield, or quality. This review focuses on the narrowly defined ERF subfamily, evaluates the evidence linking classification, transcriptional regulation, protein stability, and stress phenotypes, and examines breeding strategies based on molecular markers, tissue-specific expression, cis-regulatory editing, and favorable alleles. We argue that progress now depends on causal analysis under combined stresses and multi-environment yield validation, enabling stress protection to be decoupled from agronomic penalties.