Freezing xylem conduits with liquid nitrogen creates artifactual embolisms in water-stressed broadleaf trees

Toshihiro Umebayashi, Mayumi Y. Ogasa, Naoko Miki, Yasuhiro Utsumi, Tomoyuki Haishi, Kenji Fukuda

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Key message: Freezing with liquid nitrogen promotes the expansion of air in water columns of water-stressed, intact trees that are not transpiring. Abstract: In analyses of the distribution of water-filled and embolized conduits, xylem sap is frozen with liquid nitrogen and visualized using cryo-scanning electron microscopy (cryo-SEM). However, artifacts may be introduced during preparation of samples for these analyses. If the xylem is frozen intact, conduits may embolize during freezing when xylem water potential (Ψxylem) is substantially negative, whereas rehydration to release negative pressure may induce artifactual refilling. To evaluate these sampling phenomena during dehydration and rehydration, we monitored dynamic changes in xylem functional status in the stem of Dendropanax trifidus by compact magnetic resonance imaging (CMRI). We also visualized the water distribution in xylem (under low Ψxylem and with no transpiration) after freezing D. trifidus and Carpinus tschonoskii stems with liquid nitrogen. Artifactual refilling of embolized conduits was sometimes observed in D. trifidus samples cut underwater prior to freezing; however, the extent of refilling may have no influence on hydraulic measurements. Living cells in all samples were dramatically restored after rehydration by cutting underwater. In the current-year xylem, intact saplings of C. tschonoskii frozen with liquid nitrogen after dehydration had a greater number of embolized vessels than samples cut underwater. When a low Ψxylem (≤−2.5 MPa) was maintained, artifactual embolisms were rarely observed in samples directly frozen after rehydration. Thus, relaxation of negative Ψxylem and rehydration are important factors for consideration when assessing the distribution of embolized conduits by cryo-SEM.

Original languageEnglish
Pages (from-to)305-316
Number of pages12
JournalTrees - Structure and Function
Volume30
Issue number1
DOIs
Publication statusPublished - Feb 1 2016

Fingerprint

Xylem
embolism
xylem
Embolism
Freezing
freezing
Nitrogen
rehydration
liquid
liquids
Water
Fluid Therapy
nitrogen
water
Cryoelectron Microscopy
water distribution
desiccation (plant physiology)
sampling
Dehydration
Dendropanax

Keywords

  • Carpinus tschonoskii
  • CMRI
  • Cryo-SEM
  • Dendropanax trifidus
  • Embolism
  • Water stress

ASJC Scopus subject areas

  • Forestry
  • Plant Science
  • Physiology
  • Ecology

Cite this

Freezing xylem conduits with liquid nitrogen creates artifactual embolisms in water-stressed broadleaf trees. / Umebayashi, Toshihiro; Ogasa, Mayumi Y.; Miki, Naoko; Utsumi, Yasuhiro; Haishi, Tomoyuki; Fukuda, Kenji.

In: Trees - Structure and Function, Vol. 30, No. 1, 01.02.2016, p. 305-316.

Research output: Contribution to journalArticle

Umebayashi, Toshihiro ; Ogasa, Mayumi Y. ; Miki, Naoko ; Utsumi, Yasuhiro ; Haishi, Tomoyuki ; Fukuda, Kenji. / Freezing xylem conduits with liquid nitrogen creates artifactual embolisms in water-stressed broadleaf trees. In: Trees - Structure and Function. 2016 ; Vol. 30, No. 1. pp. 305-316.
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