Deciphering the ″Developmental Code″: A Comprehensive Review of Regulatory Mechanisms in Tomato Trichomes

Trichomes serve as essential physical and chemical barriers against biotic and abiotic stresses. Unlike the unicellular trichomes of Arabidopsis thaliana, tomato trichomes are multicellular structures, making them a valuable system for studying cell division and morphogenesis. Their development is governed by a sophisticated regulatory framework involving transcription factors (e.g., HD-ZIP IV, MYB, ZFP, bHLH), phytohormonal signaling, cytoskeletal dynamics, and cell wall remodeling proteins, alongside environmental cues. Phytohormones modulate initiation and patterning, cytoskeletal components shape morphology, and cell wall modifications facilitate elongation. Additionally, developmental stages and environmental factors dynamically influence these processes. This review synthesizes current knowledge on tomato trichome biology, encompassing their developmental mechanisms, genetic regulation, mutant phenotypes, and secondary metabolite synthesis. We further highlight research gaps and propose future directions to advance this field.