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No gas source, no problem: proximity to pre-existing embolism and segmentation affect embolism spreading in angiosperm xylem by gas diffusion
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  • Xinyi Guan,
  • Luciano Pereira,
  • Scott McAdam,
  • Kun-Fang Cao,
  • Steven Jansen
Xinyi Guan
Institute of Systematic Botany and Ecology, Ulm University,
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Luciano Pereira
Institute of Systematic Botany and Ecology, Ulm University,
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Scott McAdam
Purdue University
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Kun-Fang Cao
State Key Laboratory for Conservation and Utilisation of Subtropical Agro-Bioresources, Guangxi University
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Steven Jansen
Institute of Systematic Botany and Ecology, Ulm University
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Abstract

Embolism spreading in dehydrating angiosperm xylem is driven by gas movement between embolised and sap-filled conduits. Here, we examine how proximity to pre-existing embolism and hydraulic segmentation affect embolism propagation. Based on the optical method, we compared xylem embolism resistance between detached leaves and leaves attached to branches, and between intact leaves and leaves with cut minor veins for six species. Moreover, we directly compared the optical and pneumatic method on detached leaves. Embolism resistance of detached leaves was significantly lower than leaves attached to stems, except for two species with all vessels ending in their petioles. Cutting of minor veins showed limited embolism spreading in minor veins near the cuts prior to major veins. Moreover, there was strong agreement in embolism resistance between the optical and pneumatic method, with minor differences occurring during early stages of embolism formation. We conclude that embolism resistance may represent a relative trait, depending on the proximity and connectivity to pre-existing embolism as a gas source. Since embolism formation may not rely on a certain pressure difference threshold between functional and embolised conduits, we suggest that embolism is facilitated by pressure-driven gas diffusion, while hydraulic segmentation can prevent embolism propagation by reducing gas diffusion.

Peer review status:Published

17 Nov 2020Submitted to Plant, Cell & Environment
17 Nov 2020Submission Checks Completed
17 Nov 2020Assigned to Editor
18 Nov 2020Reviewer(s) Assigned
06 Jan 2021Review(s) Completed, Editorial Evaluation Pending
07 Jan 2021Editorial Decision: Revise Minor
14 Jan 20211st Revision Received
16 Jan 2021Submission Checks Completed
16 Jan 2021Assigned to Editor
18 Jan 2021Review(s) Completed, Editorial Evaluation Pending
18 Jan 2021Editorial Decision: Accept
02 Feb 2021Published in Plant, Cell & Environment. 10.1111/pce.14016