TY - JOUR
T1 - Leaf membrane leakage and xylem hydraulic failure define the point of no return in drought-induced tree mortality in Cupressus sempervirens
AU - Alon, Asaf
AU - Cohen, Shabtai
AU - Burlett, Regis
AU - Eselson, Elena
AU - Riov, Joseph
AU - Delzon, Sylvain
AU - David-Schwartz, Rakefet
N1 - Publisher Copyright:
© 2024 The Author(s). Physiologia Plantarum published by John Wiley & Sons Ltd on behalf of Scandinavian Plant Physiology Society.
PY - 2024/7/1
Y1 - 2024/7/1
N2 - Measurements of resistance to embolism suggest that Cupressus sempervirens has a stem xylem that resists embolism at very negative water potentials, with 50% embolism (P50) at water potentials of approximately −10 MPa. However, field observations in a semi-arid region suggest tree mortality occurs before 10% embolism. To explore the interplay between embolism and plant mortality, we conducted a controlled drought experiment involving two types of CS seedlings: a local seed source (S-type) and a drought-resistant clone propagated from a semi-arid forest (C-type). We measured resistance to embolism, leaf relative water content (RWC), water potential, photosynthesis, electrolyte leakage (EL), plant water loss, leaf hydraulic conductivity, and leaf non-structural carbohydrate (NSC) content during plant dehydration and before rewatering. All measured individuals were monitored for survival or mortality. While the S- and C-types differed in P50, transpiration, and mortality rates, both displayed seedling mortality corresponding to threshold values of 52–55% leaf RWC, 55% and 18.5% percent loss of conductivity (PLC) in the xylem, which corresponds to 48% and 37% average EL values for S and C types, respectively. Although C-type C. sempervirens NSC content increased in response to drought, no differences were observed in NSC content between live and dead seedlings of both types. Our findings do not fully explain tree mortality in the field but they do indicate that loss of membrane integrity occurs before or at xylem water potential, leading to hydraulic failure.
AB - Measurements of resistance to embolism suggest that Cupressus sempervirens has a stem xylem that resists embolism at very negative water potentials, with 50% embolism (P50) at water potentials of approximately −10 MPa. However, field observations in a semi-arid region suggest tree mortality occurs before 10% embolism. To explore the interplay between embolism and plant mortality, we conducted a controlled drought experiment involving two types of CS seedlings: a local seed source (S-type) and a drought-resistant clone propagated from a semi-arid forest (C-type). We measured resistance to embolism, leaf relative water content (RWC), water potential, photosynthesis, electrolyte leakage (EL), plant water loss, leaf hydraulic conductivity, and leaf non-structural carbohydrate (NSC) content during plant dehydration and before rewatering. All measured individuals were monitored for survival or mortality. While the S- and C-types differed in P50, transpiration, and mortality rates, both displayed seedling mortality corresponding to threshold values of 52–55% leaf RWC, 55% and 18.5% percent loss of conductivity (PLC) in the xylem, which corresponds to 48% and 37% average EL values for S and C types, respectively. Although C-type C. sempervirens NSC content increased in response to drought, no differences were observed in NSC content between live and dead seedlings of both types. Our findings do not fully explain tree mortality in the field but they do indicate that loss of membrane integrity occurs before or at xylem water potential, leading to hydraulic failure.
UR - http://www.scopus.com/inward/record.url?scp=85201248338&partnerID=8YFLogxK
U2 - 10.1111/ppl.14467
DO - 10.1111/ppl.14467
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C2 - 39140130
AN - SCOPUS:85201248338
SN - 0031-9317
VL - 176
JO - Physiologia Plantarum
JF - Physiologia Plantarum
IS - 4
M1 - e14467
ER -