Beyond Survival: The Unique Salt Secretion and Ion Homeostasis Mechanisms in Limonium bicolor Under Salt Stress

Abstract

Soil salinization poses a significant threat to global agriculture. Limonium bicolor, a recretohalophyte, has evolved a unique and efficient salt tolerance mechanism centered on epidermal salt glands for secreting excess salts. This review systematically synthesizes the multilevel salt tolerance strategies in Limonium bicolor, covering the structural basis of its multicellular salt glands, the molecular regulatory networks governing their development including core transcription factors (e.g., WD40, bHLH, MYB) and signaling pathways (e.g., cytokinin, MAPK cascades, Ca²⁺, NO) and the precise ion transport mechanisms for salt secretion. Furthermore, it elaborates on the supportive physiological adaptations, such as osmotic regulation and antioxidant defense, alongside the reprogramming of photosynthesis and secondary metabolism. The identification of key genes with potential for enhancing salt tolerance in other species underscores the translational value of this model halophyte. This integrated overview highlights the synergistic operation of structural, molecular, regulatory, and physiological layers, providing insights for future research and the breeding of salt-tolerant crops to utilize saline lands.