Too dry to survive: Leaf hydraulic failure in two Salvia species can be predicted on the basis of water content

• Published in: Plant physiology and biochemistry 2021-09, Vol.166, p.215-224
• Main Authors: Abate, Elisa, Nardini, Andrea, Petruzzellis, Francesco, Trifilò, Patrizia
• Format: Article
• Language: English
• Subjects: Climate change; Leaf hydraulic failure; Leaf shrinkage; Mediterranean species; Membrane damages; Rehydration capacity; Water content
• ISSN: 0981-9428; 1873-2690
• DOI: 10.1016/j.plaphy.2021.05.046

Global warming is exposing plants to increased risks of drought-driven mortality. Recent advances suggest that hydraulic failure is a key process leading to plant death, and the identification of simple and reliable proxies of species-specific risk of irreversible hydraulic damage is urgently required. We assessed the predictive power of leaf water content and shrinkage for monitoring leaf hydraulic failure in two Mediterranean native species, Salvia ceratophylloides (Sc) and S. officinalis (So). The study species showed significant differences in relative water content (RWC) thresholds inducing loss of rehydration capacity, as well as leaf hydraulic conductance (KL) impairment. Sc turned out to be more resistant to drought than So. However, Sc and So showed different leaf saturated water content values, so that different RWC values actually corresponded to similar absolute leaf water content. Our findings suggest that absolute leaf water content and leaf water potential, but not RWC, are reliable parameters for predicting the risk of leaf hydraulic impairment of two Salvia species, and their potential risk of irreversible damage under severe drought. Moreover, the lack of any KL decline until the turgor loss point in Sc, coupled to consistent leaf shrinkage, rejects the hypothesis to use leaf shrinkage as a proxy to predict KL vulnerability, at least in species with high leaf capacitance. Robust linear correlations between KL decline and electrolyte leakage measurements suggested a role of membrane damage in driving leaf hydraulic collapse. •Hydraulic failure is a major correlate of drought-driven plant death.•Simple parameters predicting the risk of irreversible hydraulic failure are needed.•Leaf hydraulic damage occurred at different RWC values in two Salvia species.•Absolute water content and cell membrane integrity predicted hydraulic failure.