title: Elevated [CO2] magnifies isoprene emissions under heat and improves thermal resistance in hybrid aspen.
abstract: Isoprene emissions importantly protect plants from heat stress, but the emissions become inhibited by instantaneous increase of [CO2], and it is currently unclear how isoprene-emitting plants cope with future more frequent and severe heat episodes under high [CO2]. Hybrid aspen (Populus tremula x Populus tremuloides) saplings grown under ambient [CO2] of 380 μmol mol(-1) and elevated [CO2] of 780 μmol mol(-1) were used to test the hypothesis that acclimation to elevated [CO2] reduces the inhibitory effect of high [CO2] on emissions. Elevated-[CO2]-grown plants had greater isoprene emission capacity and a stronger increase of isoprene emissions with increasing temperature. High temperatures abolished the instantaneous [CO2] sensitivity of isoprene emission, possibly due to removing the substrate limitation resulting from curbed cycling of inorganic phosphate. As a result, isoprene emissions were highest in elevated-[CO2]-grown plants under high measurement [CO2]. Overall, elevated growth [CO2] improved heat resistance of photosynthesis, in particular, when assessed under high ambient [CO2] and the improved heat resistance was associated with greater cellular sugar and isoprene concentrations. Thus, contrary to expectations, these results suggest that isoprene emissions might increase in the future.
authors.affiliation: Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi 1, Tartu 51014, Estonia.
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Sun
authors.forename: Katja
authors.initials: K
authors.lastname: Hüve
authors.forename: Vivian
authors.initials: V
authors.lastname: Vislap
authors.forename: Ülo
authors.initials: Ü
authors.lastname: Niinemets
mesh_terms: D000064:Acclimatization; D000222:Adaptation, Physiological; D002070:Butadienes / Q000378:metabolism*; D002245:Carbon Dioxide / Q000494:pharmacology; D002678:Chimera; D018869:Heat-Shock Response; D045782:Hemiterpenes / Q000378:metabolism*; D008027:Light; D010420:Pentanes / Q000378:metabolism*; D018515:Plant Leaves / Q000033:anatomy & histology / Q000737:chemistry; D032107:Populus / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D013696:Temperature
chemical_list: D002070:Butadienes; D045782:Hemiterpenes; D010420:Pentanes; C005059:isoprene; D002245:Carbon Dioxide
keywords: BVOCs; foliage traits; future emissions; heat stress; isoprene CO2 response; temperature response.