TY - JOUR
T1 - Grapevine petioles are more sensitive to drought induced embolism than stems
T2 - evidence from in vivo MRI and microcomputed tomography observations of hydraulic vulnerability segmentation
AU - Hochberg, Uri
AU - Albuquerque, Caetano
AU - Rachmilevitch, Shimon
AU - Cochard, Herve
AU - David-Schwartz, Rakefet
AU - Brodersen, Craig R.
AU - McElrone, Andrew
AU - Windt, Carel W.
N1 - Publisher Copyright: © 2015 John Wiley & Sons Ltd
PY - 2016/9/1
Y1 - 2016/9/1
N2 - The ‘hydraulic vulnerability segmentation’ hypothesis predicts that expendable distal organs are more susceptible to water stress-induced embolism than the main stem of the plant. In the current work, we present the first in vivo visualization of this phenomenon. In two separate experiments, using magnetic resonance imaging or synchrotron-based microcomputed tomography, grapevines (Vitis vinifera) were dehydrated while simultaneously scanning the main stems and petioles for the occurrence of emboli at different xylem pressures (Ψx). Magnetic resonance imaging revealed that 50% of the conductive xylem area of the petioles was embolized at a Ψx of −1.54 MPa, whereas the stems did not reach similar losses until −1.9 MPa. Microcomputed tomography confirmed these findings, showing that approximately half the vessels in the petioles were embolized at a Ψx of −1.6 MPa, whereas only few were embolized in the stems. Petioles were shown to be more resistant to water stress-induced embolism than previously measured with invasive hydraulic methods. The results provide the first direct evidence for the hydraulic vulnerability segmentation hypothesis and highlight its importance in grapevine responses to severe water stress. Additionally, these data suggest that air entry through the petiole into the stem is unlikely in grapevines during drought.
AB - The ‘hydraulic vulnerability segmentation’ hypothesis predicts that expendable distal organs are more susceptible to water stress-induced embolism than the main stem of the plant. In the current work, we present the first in vivo visualization of this phenomenon. In two separate experiments, using magnetic resonance imaging or synchrotron-based microcomputed tomography, grapevines (Vitis vinifera) were dehydrated while simultaneously scanning the main stems and petioles for the occurrence of emboli at different xylem pressures (Ψx). Magnetic resonance imaging revealed that 50% of the conductive xylem area of the petioles was embolized at a Ψx of −1.54 MPa, whereas the stems did not reach similar losses until −1.9 MPa. Microcomputed tomography confirmed these findings, showing that approximately half the vessels in the petioles were embolized at a Ψx of −1.6 MPa, whereas only few were embolized in the stems. Petioles were shown to be more resistant to water stress-induced embolism than previously measured with invasive hydraulic methods. The results provide the first direct evidence for the hydraulic vulnerability segmentation hypothesis and highlight its importance in grapevine responses to severe water stress. Additionally, these data suggest that air entry through the petiole into the stem is unlikely in grapevines during drought.
KW - cavitation
KW - hydraulic conductance
KW - Vitis vinifera
KW - vulnerability curves
KW - xylem
UR - http://www.scopus.com/inward/record.url?scp=84958781145&partnerID=8YFLogxK
U2 - https://doi.org/10.1111/pce.12688
DO - https://doi.org/10.1111/pce.12688
M3 - Article
C2 - 26648337
SN - 0140-7791
VL - 39
SP - 1886
EP - 1894
JO - Plant, Cell and Environment
JF - Plant, Cell and Environment
IS - 9
ER -