title: Climate-resilient agroforestry: physiological responses to climate change and engineering of crassulacean acid metabolism (CAM) as a mitigation strategy.
abstract: Global climate change threatens the sustainability of agriculture and agroforestry worldwide through increased heat, drought, surface evaporation and associated soil drying. Exposure of crops and forests to warmer and drier environments will increase leaf:air water vapour-pressure deficits (VPD), and will result in increased drought susceptibility and reduced productivity, not only in arid regions but also in tropical regions with seasonal dry periods. Fast-growing, short-rotation forestry (SRF) bioenergy crops such as poplar (Populus spp.) and willow (Salix spp.) are particularly susceptible to hydraulic failure following drought stress due to their isohydric nature and relatively high stomatal conductance. One approach to sustaining plant productivity is to improve water-use efficiency (WUE) by engineering crassulacean acid metabolism (CAM) into C3 crops. CAM improves WUE by shifting stomatal opening and primary CO2 uptake and fixation to the night-time when leaf:air VPD is low. CAM members of the tree genus Clusia exemplify the compatibility of CAM performance within tree species and highlight CAM as a mechanism to conserve water and maintain carbon uptake during drought conditions. The introduction of bioengineered CAM into SRF bioenergy trees is a potentially viable path to sustaining agroforestry production systems in the face of a globally changing climate.
authors.affiliation: School of Biology, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.|Biosciences Division, Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6407, USA.
authors.forename: Anne M
authors.initials: AM
authors.lastname: Borland
authors.affiliation: Climate Change Science Institute, Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6301, USA.
authors.forename: Stan D
authors.initials: SD
authors.lastname: Wullschleger
authors.affiliation: Biosciences Division, Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6407, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Weston
authors.affiliation: Department of Plant Sciences, Institute of Integrative Biology, University of Liverpool, Liverpool, L69 7ZB, UK.
authors.forename: James
authors.initials: J
authors.lastname: Hartwell
authors.affiliation: Biosciences Division, Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6407, USA.
authors.forename: Gerald A
authors.initials: GA
authors.lastname: Tuskan
authors.affiliation: Biosciences Division, Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6407, USA.
authors.forename: Xiaohan
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of Biochemistry and Molecular Biology, MS330, University of Nevada, Reno, NV, 89557-0330, USA.
authors.forename: John C
authors.initials: JC
authors.lastname: Cushman
mesh_terms: D000383:Agriculture / Q000379:methods / Q000639:trends; D057231:Climate Change; D055864:Droughts; D017753:Ecosystem; D016468:Forestry / Q000379:methods*; D005818:Genetic Engineering / Q000379:methods; D000069600:Plant Breeding / Q000379:methods*; D032107:Populus; D032108:Salix; D014197:Trees / Q000235:genetics / Q000378:metabolism* / Q000502:physiology
keywords: CO2; carbon reactions; drought; global climate change; photosynthesis; stomata; water relations; water-use efficiency