Desiccation tolerance mechanisms in the green lineage and beyond.

Water is essential for life on Earth, yet some plants can survive the near-complete loss of cellular water, a trait known as desiccation tolerance. Although rare in vegetative tissues of vascular plants, desiccation tolerance is scattered across the plant kingdom, where it likely enabled early terrestrialization and supports survival in environments with prolonged or intermittent drying. Large-scale multi-omics, comparative, and functional studies over the past decade suggest that desiccation tolerance evolved primarily through the repurposing of ancient stress-resilience mechanisms, giving rise to convergent phenotypes where cells are protected and stabilized during extreme dehydration. In photosynthetic lineages, desiccation is further compounded by light-dependent photooxidative stress, requiring specialized mechanisms that safeguard the photosynthetic apparatus during both drying and recovery. Here, we synthesize our current understanding of the evolutionary origins and core mechanisms underlying plant desiccation tolerance and place them within a broader comparative context across kingdoms. We highlight how genome-scale datasets suggest desiccation tolerance is an emergent, systems-level phenotype coordinated across biological scales. Finally, we discuss the translational opportunities and constraints of desiccation tolerance in agriculture, medicine, biotechnology, and related fields.