title: Drought increases heat tolerance of leaf respiration in Eucalyptus globulus saplings grown under both ambient and elevated atmospheric [CO2] and temperature.
abstract: Climate change is resulting in increasing atmospheric [CO2], rising growth temperature (T), and greater frequency/severity of drought, with each factor having the potential to alter the respiratory metabolism of leaves. Here, the effects of elevated atmospheric [CO2], sustained warming, and drought on leaf dark respiration (R(dark)), and the short-term T response of R(dark) were examined in Eucalyptus globulus. Comparisons were made using seedlings grown under different [CO2], T, and drought treatments. Using high resolution T-response curves of R(dark) measured over the 15-65 °C range, it was found that elevated [CO2], elevated growth T, and drought had little effect on rates of R(dark) measured at T <35 °C and that there was no interactive effect of [CO2], growth T, and drought on T response of R(dark). However, drought increased R(dark) at high leaf T typical of heatwave events (35-45 °C), and increased the measuring T at which maximal rates of R(dark) occurred (Tmax) by 8 °C (from 52 °C in well-watered plants to 60 °C in drought-treated plants). Leaf starch and soluble sugars decreased under drought and elevated growth T, respectively, but no effect was found under elevated [CO2]. Elevated [CO2] increased the Q 10 of R(dark) (i.e. proportional rise in R(dark) per 10 °C) over the 15-35 °C range, while drought increased Q 10 values between 35 °C and 45 °C. Collectively, the study highlights the dynamic nature of the T dependence of R dark in plants experiencing future climate change scenarios, particularly with respect to drought and elevated [CO2].
authors.affiliation: Division of Plant Sciences, Research School of Biology, Building 46, The Australian National University, Canberra, ACT, 0200, Australia Department of Geosciences, Princeton University, Guyot Hall, Princeton, NJ 08544, USA.
authors.forename: Paul P G
authors.initials: PP
authors.lastname: Gauthier
authors.affiliation: Division of Plant Sciences, Research School of Biology, Building 46, The Australian National University, Canberra, ACT, 0200, Australia Hawkesbury Institute for the Environment, University of Western Sydney, Hawkesbury Campus, Locked Bag 1797, Penrith, NSW, 2751, Australia.
authors.forename: Kristine Y
authors.initials: KY
authors.lastname: Crous
authors.affiliation: Division of Plant Sciences, Research School of Biology, Building 46, The Australian National University, Canberra, ACT, 0200, Australia Department of Horticulture, Agricultural University Peshawar, 25130, Khyber Pakhtunkhwa, Pakistan.
authors.forename: Gohar
authors.initials: G
authors.lastname: Ayub
authors.affiliation: Hawkesbury Institute for the Environment, University of Western Sydney, Hawkesbury Campus, Locked Bag 1797, Penrith, NSW, 2751, Australia Institute of Ecology & Environmental Science, Nanchang Institute of Technology, No. 289 Tianxiang Road, Nanchang 330099, China.
authors.forename: Honglang
authors.initials: H
authors.lastname: Duan
authors.affiliation: Division of Plant Sciences, Research School of Biology, Building 46, The Australian National University, Canberra, ACT, 0200, Australia Faculty of Agriculture, University of Peradeniya, Peradeniya, 20400, Sri Lanka.
authors.forename: Lasantha K
authors.initials: LK
authors.lastname: Weerasinghe
authors.affiliation: Hawkesbury Institute for the Environment, University of Western Sydney, Hawkesbury Campus, Locked Bag 1797, Penrith, NSW, 2751, Australia.
authors.forename: David S
authors.initials: DS
authors.lastname: Ellsworth
authors.affiliation: Hawkesbury Institute for the Environment, University of Western Sydney, Hawkesbury Campus, Locked Bag 1797, Penrith, NSW, 2751, Australia.
authors.forename: Mark G
authors.initials: MG
authors.lastname: Tjoelker
authors.affiliation: Division of Plant Sciences, Research School of Biology, Building 46, The Australian National University, Canberra, ACT, 0200, Australia.
authors.forename: John R
authors.initials: JR
authors.lastname: Evans
authors.affiliation: Hawkesbury Institute for the Environment, University of Western Sydney, Hawkesbury Campus, Locked Bag 1797, Penrith, NSW, 2751, Australia.
authors.forename: David T
authors.initials: DT
authors.lastname: Tissue
authors.affiliation: Division of Plant Sciences, Research School of Biology, Building 46, The Australian National University, Canberra, ACT, 0200, Australia ARC Centre of Excellence in Plant Energy Biology, The Australian National University, Canberra, ACT, 0200, Australia owen.atkin@anu.edu.au.
authors.forename: Owen K
authors.initials: OK
authors.lastname: Atkin
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects*; D000704:Analysis of Variance; D001272:Atmosphere; D001315:Australia; D002241:Carbohydrates / Q000032:analysis; D002245:Carbon Dioxide / Q000494:pharmacology*; D019069:Cell Respiration / Q000187:drug effects; D003624:Darkness; D055864:Droughts; D005052:Eucalyptus / Q000187:drug effects / Q000254:growth & development* / Q000502:physiology*; D006358:Hot Temperature; D010641:Phenotype; D018515:Plant Leaves / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology*
chemical_list: D002241:Carbohydrates; D002245:Carbon Dioxide
keywords: Dark respiration; Eucalyptus globulus; Q10; drought; elevated CO2; temperature response.