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Long-term water stress leads to acclimation of drought sensitivity of photosynthetic capacity in xeric but not riparian Eucalyptus species

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Title: Long-term water stress leads to acclimation of drought sensitivity of photosynthetic capacity in xeric but not riparian Eucalyptus species
Authors: Zhou, S-X
Medlyn, BE
Prentice, IC
Item Type: Journal Article
Abstract: Background and Aims Experimental drought is well documented to induce a decline in photosynthetic capacity. However, if given time to acclimate to low water availability, the photosynthetic responses of plants to low soil moisture content may differ from those found in short-term experiments. This study aims to test whether plants acclimate to long-term water stress by modifying the functional relationships between photosynthetic traits and water stress, and whether species of contrasting habitat differ in their degree of acclimation. Methods Three Eucalyptus taxa from xeric and riparian habitats were compared with regard to their gas exchange responses under short- and long-term drought. Photosynthetic parameters were measured after 2 and 4 months of watering treatments, namely field capacity or partial drought. At 4 months, all plants were watered to field capacity, then watering was stopped. Further measurements were made during the subsequent ‘drying-down’, continuing until stomata were closed. Key Results Two months of partial drought consistently reduced assimilation rate, stomatal sensitivity parameters (g1), apparent maximum Rubisco activity (V′cmaxVcmax′) and maximum electron transport rate (J′maxJmax′). Eucalyptus occidentalis from the xeric habitat showed the smallest decline in V′cmaxVcmax′ and J′maxJmax′; however, after 4 months, V′cmaxVcmax′ and J′maxJmax′ had recovered. Species differed in their degree of V′cmaxVcmax′ acclimation. Eucalyptus occidentalis showed significant acclimation of the pre-dawn leaf water potential at which the V′cmaxVcmax′ and ‘true’ Vcmax (accounting for mesophyll conductance) declined most steeply during drying-down. Conclusions The findings indicate carbon loss under prolonged drought could be over-estimated without accounting for acclimation. In particular, (1) species from contrasting habitats differed in the magnitude of V′cmax reduction in short-term drought; (2) long-term drought allowed the possibility of acclimation, such that V′cmax reduction was mitigated; (3) xeric species showed a greater degree of V′cmax acclimation; and (4) photosynthetic acclimation involves hydraulic adjustments to reduce water loss while maintaining photosynthesis.
Issue Date: 22-Oct-2015
Date of Acceptance: 10-Sep-2015
URI: http://hdl.handle.net/10044/1/56802
DOI: https://dx.doi.org/10.1093/aob/mcv161
ISSN: 1095-8290
Publisher: Oxford University Press (OUP)
Start Page: 133
End Page: 144
Journal / Book Title: Annals of Botany
Volume: 117
Issue: 1
Copyright Statement: This is a pre-copyedited, author-produced PDF of an article accepted for publication in Annals of Botany following peer review. The version of record Shuang-Xi Zhou, Belinda E. Medlyn, Iain Colin Prentice; Long-term water stress leads to acclimation of drought sensitivity of photosynthetic capacity in xeric but not riparian Eucalyptus species, Annals of Botany, Volume 117, Issue 1, 1 January 2016, Pages 133–144, is available online at: https://dx.doi.org/10.1093/aob/mcv161
Sponsor/Funder: AXA Research Fund
Funder's Grant Number: AXA Chair Programme in Biosphere and Climate Impacts
Keywords: Science & Technology
Life Sciences & Biomedicine
Plant Sciences
Drought acclimation
photosynthesis
water stress
V-cmax
J(max)
water use efficiency
stomatal conductance
mesophyll conductance
Huber value
hydraulic adjustment
riparian Eucalyptus camaldulensis
xeric Eucalyptus occidentalis
DECREASED RUBISCO ACTIVITY
STOMATAL CONDUCTANCE
MESOPHYLL CONDUCTANCE
QUERCUS-ILEX
PHYSIOLOGICAL-RESPONSES
BIOCHEMICAL LIMITATIONS
DIFFUSION CONDUCTANCE
THROUGHFALL EXCLUSION
GAS-EXCHANGE
C-3 PLANTS
Jmax
Vcmax
Acclimatization
Carbon Dioxide
Carbon Isotopes
Dehydration
Droughts
Ecosystem
Eucalyptus
Light
Photosynthesis
Plant Leaves
Principal Component Analysis
Species Specificity
Water
0607 Plant Biology
0602 Ecology
Plant Biology & Botany
Publication Status: Published
Appears in Collections:Department of Life Sciences
Grantham Institute for Climate Change
Faculty of Natural Sciences