title: Acclimation of photosynthetic tolerance to acute heat stress at elevated CO₂ and N.
abstract: Determining interactive effects of pre-heat-stress, CO2 and N on photosynthetic thermotolerance is necessary for predicting plant responses to global change. We grew Hordeum vulgare (barley, C3) and Zea mays (corn, C4) at current or elevated CO2 (370 and 700 ppm) and limiting or optimal soil N (0.5 and 7.5mM). We assessed basal and inducible thermotolerance of net photosynthesis (Pn), photosystem II efficiency [Formula: see text] , photochemical quenching (qp), carboxylation efficiency (CE), and rubisco activase content. Inducible thermotolerance was measured on plants which were pre-heat-stressed (PHS) for 4h before heat stress. We also assayed content of several major heat-shock proteins (HSPs), as HSPs are primary adaptations to heat stress and affected by N. Acclimation of photosynthetic thermotolerance was dependent on species, CO2 and N treatment and the component in the photosynthetic processes. PHS had a positive effect on the production of HSP60 and sHSP in low-N barley and corn. These results indicate that stimulatory effects of elevated CO2 at normal temperatures on photosynthesis may be partly changed by the different interactive effects of CO2, heat stress and N for species with different photosynthetic pathways. Thus, PHS, CO2 and N effects on photosynthetic thermotolerance may contribute to changes in plant productivity, distribution, and diversity.
authors.affiliation: International Center for Ecology, Meteorology and Environment, School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China. Electronic address: dwng@illinois.edu.
authors.forename: Dan
authors.initials: D
authors.lastname: Wang
authors.affiliation: International Center for Ecology, Meteorology and Environment, School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China.
authors.forename: Jiazhi
authors.initials: J
authors.lastname: Fan
authors.affiliation: Department of Environmental Sciences, University of Toledo, Toledo, OH 43606, USA.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Heckathorn
mesh_terms: D000064:Acclimatization; D002245:Carbon Dioxide / Q000378:metabolism*; D057231:Climate Change; D006360:Heat-Shock Proteins / Q000378:metabolism*; D001467:Hordeum / Q000378:metabolism*; D006358:Hot Temperature; D009584:Nitrogen / Q000378:metabolism*; D010788:Photosynthesis; D003313:Zea mays / Q000378:metabolism*
chemical_list: D006360:Heat-Shock Proteins; D002245:Carbon Dioxide; D009584:Nitrogen
keywords: Climate change; Heat shock proteins; Thermotolerance