Brassinosteroids' regulation of plant architecture

Abstract Plant architecture as determined by shoot and root development is regulated by hormonal, metabolic, and environmental pathways. Although a number of key genes controlling plant architecture have been cloned and characterized in recent years, their roles in the developmental regulatory network and the relationship with plant hormones remain unclear. Brassinosteroids (BRs), a group of steroid phytohormones, were shown to play a central role in plant development by regulating cell proliferation, elongation, and differentiation. The core BR signaling module comprises BRASSINOSTEROID INSENSITIVE1 (BRI1), BRASSINOSTEROID INSENSITIVE2 (BIN2), and BRASSINAZOLE-RESISTANT1 (BZR1). BZR1 acts as a transcription factor that controls the expression of thousands of target genes, and is involved in hormonal cross-talk, plant development, and environmental responses. Recent studies have identified BR signaling as a critical component involved in the regulation of lateral organ development. In particular, BR signaling integrates several pathways to relieve apical dominance. Understanding the underlying mechanisms would improve crop yield through optimizing the plant architecture of crops by molecular design.