Research Advances in Molecular Mechanisms of Xylem Development in Horticultural Plants

Xylem, a critical vascular tissue extensively distributed in stems and roots, plays indispensable roles in horticultural plant development. It facilitates water and mineral transport, provides mechanical support through secondary cell wall lignification, and precisely modulates ion homeostasis (e.g., Na+/K+ balance), thereby enhancing plant resilience to abiotic stresses. Consequently, xylem function directly impacts crop yield and quality. Recent breakthroughs in molecular biology have significantly advanced our understanding of the regulatory networks governing xylem development, including key transcription factors, hormonal signaling pathways (particularly auxin, cytokinin, and brassinosteroids), and their interactions with environmental cues. This review systematically summarizes current progress on the molecular mechanisms underlying xylem differentiation, secondary wall biosynthesis, and stress-responsive vascular adaptation in horticultural species. We further discuss emerging research frontiers, existing technical challenges, and prospective directions, aiming to provide a theoretical framework for genetic improvement and precision cultivation of horticultural crops.