title: Integrated physiological and hormonal profile of heat-induced thermotolerance in Pinus radiata.
abstract: Despite great interest, not only from the economic point of view but also in terms of basic science, research on heat stress tolerance in conifers remains scarce. To fill this gap, a time-course experiment using expected temperature increase was performed aiming to identify physiological and biochemical traits that allow the characterization of heat-induced thermotolerance and recovery in Pinus radiata D. Don plants. Several physiological parameters were assessed during heat exposure and after recovery, and multiple phytohormones-abscisic acid (ABA), indole-3-acetic acid (IAA), cytokinins (CKs), gibberellins, jasmonic acid, salicylic acid (SA) and brassinosteroids-were quantified by ultra-performance liquid chromatography-mass spectrometry from unique sample. Furthermore, tissue specific stress-signaling was monitored by IAA and ABA immunolocalization. Multivariate statistical analysis of the data enabled clustering of the shorter- and longer-term effects of heat stress exposure. Two sequential physiological responses were identified: an immediate and a delayed response, essentially determined by specific phytohormones, proline, malondialdehyde and total soluble sugar patterns. Results showed that ABA and SA play a crucial role in the first stage of response to heat stress, probably due to the plant's urgent need to regulate stomatal closure and counteract the increase in oxidative membrane damage demonstrated in shorter-term exposures. However, in longer exposures and recovery, proline, total sugars, IAA and CKs seem to be more relevant. This integrated approach pinpointed some basic mechanisms of P. radiata physiological responses underlying thermotolerance processes and after recovery.
authors.affiliation: Plant Physiology, Department B.O.S., Faculty of Biology, University of Oviedo, 33006 Oviedo, Asturias, Spain.
authors.forename: Mónica
authors.initials: M
authors.lastname: Escandón
authors.affiliation: Plant Physiology, Department B.O.S., Faculty of Biology, University of Oviedo, 33006 Oviedo, Asturias, Spain mjcanal@uniovi.es meijonmonica@uniovi.es.
authors.forename: María Jesús
authors.initials: MJ
authors.lastname: Cañal
authors.affiliation: Plant Physiology, Department B.O.S., Faculty of Biology, University of Oviedo, 33006 Oviedo, Asturias, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Pascual
authors.affiliation: Department of Biology and CESAM, University of Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Glória
authors.initials: G
authors.lastname: Pinto
authors.affiliation: Department of Biology and CESAM, University of Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Barbara
authors.initials: B
authors.lastname: Correia
authors.affiliation: Department of Biology and CESAM, University of Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Joana
authors.initials: J
authors.lastname: Amaral
authors.affiliation: Plant Physiology, Department B.O.S., Faculty of Biology, University of Oviedo, 33006 Oviedo, Asturias, Spain Regional Institute for Research and Agro-Food Development in Asturias (SERIDA), Experimental station of "La Mata", 33820 Grado, Asturias, Spain mjcanal@uniovi.es meijonmonica@uniovi.es.
authors.forename: Mónica
authors.initials: M
authors.lastname: Meijón
mesh_terms: D000222:Adaptation, Physiological; D006358:Hot Temperature; D028223:Pinus / Q000502:physiology*; D010937:Plant Growth Regulators / Q000378:metabolism*
chemical_list: D010937:Plant Growth Regulators
keywords: UPLC/MS; acclimation; conifers; ecophysiological parameters; heat tolerance; phytohormone crosstalk