A trade-off between leaf water retention capacity and rehydration capacity among plant species

How plants cope with drought remains a major challenge in plant biology. Plants have evolved diverse drought resistance strategies, whether they operate synergistically or exhibit trade-offs remains a critical knowledge gap. Here, we examined drought resistance strategies across 128 plant species, encompassing diverse plant phyla, original biomes, leaf types, and growth forms. Their leaf water retention capacity, rehydration capacity, and anatomical traits of leaves were measured. Our analyses revealed a significant negative correlation between leaf water retention capacity and rehydration capacity (R² = 0.55, P < 0.001), providing compelling evidence for an trade-off between desiccation avoidance and desiccation tolerance at the leaf level. This trade-off exhibits clear anatomical underpinnings in leaf structural traits including cell size, leaf thickness, vein density, and xylem proportion. We found significant variations in both capacities across plant phyla, original biomes, and leaf types, suggesting that vascular structure evolution and habitat adaptation may be primary drivers shaping drought resistance strategies. Notably, interspecific differences in leaf water retention capacity were mainly due to variations in water loss rate rather than water storage capacity. Our findings advance mechanistic understanding of drought resistance strategies across different plant types and contribute to improved predictions of vegetation responses to climate change.