The Adaptation Mechanisms of Xerophytes: from Morphological Remodeling to Molecular Regulation

Drought stress has been recognized as a major impediment to global plant productivity and the stability of terrestrial ecosystems. Over long-term adaptation to arid environments, xerophytes have gradually developed a suite of coping strategies encompassing morphological, physiological, and molecular mechanisms, evolving unique and efficient drought resistance. Morphologically, xerophytes enhance water acquisition and reduce transpirational loss through root and leaf structural specialization and optimized root–shoot allocation. Physiologically, homeostasis is maintained via coordinated stomatal regulation, antioxidant defenses, and hormonal networks. At the molecular level, drought signals, mediated by Ca²⁺ and ABA pathways, activate diverse transcription factors to regulate the expression of stress-responsive genes. This review elucidates the definition and classification of xerophytes, analyzes the multifaceted research progress on xerophytes in China, and explores the cross-scale synergistic mechanisms underlying their drought adaptation. It provides a theoretical foundation for understanding the evolutionary logic of plant adaptation to arid environments and offers new insights for addressing global climate change and advancing sustainable agricultural development.