Outside-Xylem Vulnerability, Not Xylem Embolism, Controls Leaf Hydraulic Decline during Dehydration
| Autor: | Andrew J. McElrone, Caetano Pereira Pedroso de Albuquerque, Thomas N. Buckley, Lawren Sack, Shatara V. Townes, Christine Scoffoni, Megan K. Bartlett, Grace P. John, Craig R. Brodersen |
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| Rok vydání: | 2017 |
| Předmět: |
0106 biological sciences
0301 basic medicine Plant growth Water transport Physiology fungi Water stress Turgor pressure food and beverages Xylem Plant Science Biology medicine.disease 01 natural sciences Severe dehydration 03 medical and health sciences 030104 developmental biology Embolism Botany Genetics medicine Dehydration 010606 plant biology & botany |
| Zdroj: | Plant Physiology. 173:1197-1210 |
| ISSN: | 1532-2548 0032-0889 |
| DOI: | 10.1104/pp.16.01643 |
| Popis: | Leaf hydraulic supply is crucial to maintaining open stomata for CO2 capture and plant growth. During drought-induced dehydration, the leaf hydraulic conductance (Kleaf) declines, which contributes to stomatal closure and, eventually, to leaf death. Previous studies have tended to attribute the decline of Kleaf to embolism in the leaf vein xylem. We visualized at high resolution and quantified experimentally the hydraulic vulnerability of xylem and outside-xylem pathways and modeled their respective influences on plant water transport. Evidence from all approaches indicated that the decline of Kleaf during dehydration arose first and foremost due to the vulnerability of outside-xylem tissues. In vivo x-ray microcomputed tomography of dehydrating leaves of four diverse angiosperm species showed that, at the turgor loss point, only small fractions of leaf vein xylem conduits were embolized, and substantial xylem embolism arose only under severe dehydration. Experiments on an expanded set of eight angiosperm species showed that outside-xylem hydraulic vulnerability explained 75% to 100% of Kleaf decline across the range of dehydration from mild water stress to beyond turgor loss point. Spatially explicit modeling of leaf water transport pointed to a role for reduced membrane conductivity consistent with published data for cells and tissues. Plant-scale modeling suggested that outside-xylem hydraulic vulnerability can protect the xylem from tensions that would induce embolism and disruption of water transport under mild to moderate soil and atmospheric droughts. These findings pinpoint outside-xylem tissues as a central locus for the control of leaf and plant water transport during progressive drought. |
| Databáze: | OpenAIRE |
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