caa a22 4500 445841109 CHVBK 20180317145344.0 cr unu---uuuuu 170323e20110601xx s 000 0 eng 10.1007/s10725-010-9549-7 doi (NATIONALLICENCE)springer-10.1007/s10725-010-9549-7 Interactions of temperature and light quality on phytohormone-mediated elongation of Helianthus annuus hypocotyls [Elektronische Daten] [Leonid Kurepin, Linda Walton, Richard Pharis, R. Neil Emery, David Reid] Two important environmental signals, shade light, where the red/far-red (R/FR) light ratio is reduced, and elevated temperatures can each promote shoot growth. We examined their interactions using hypocotyl elongation of young sunflower (Helianthus annuus) seedlings, and we did this in the context of a possible hormonal mechanism for the growth increases that were induced by each environmental signal. Seedlings were subjected to combinations of six different temperatures (10, 15, 20, 25, 30 and 35°C) and four R/FR ratios (normal at 1.2 and reduced at 0.9, 0.6 and 0.3). Hypocotyl length was significantly increased by each of elevated temperature and FR enrichment. The magnitude of elongation induced by FR enrichment (low R/FR ratios) was dependent on temperature, with maximal effects of FR enrichment being seen at 20°C. Hypocotyl tissue concentrations of four endogenous gibberellins (GAs) and abscisic acid (ABA) were measured using the stable isotope dilution method. Hypocotyl ethylene evolution was also assessed. Thus, hypocotyl growth in both normal and shade light is highly dependent on temperature, with the most significant increases in FR-induced growth occurring at 20 and 25°C. A causal involvement of endogenous hormones, especially the GAs, in the growth that is induced by elevated temperatures, as well as in FR-induced growth, is strongly implied, with temperature being the stronger signal. Springer Science+Business Media B.V., 2010 Gibberellins nationallicence Elongation nationallicence Temperature nationallicence Red to far-red ratio nationallicence Abscisic acid nationallicence Ethylene nationallicence Kurepin Leonid Department of Biological Sciences, University of Calgary, Calgary, AB, Canada aut Walton Linda Department of Biological Sciences, University of Calgary, Calgary, AB, Canada aut Pharis Richard Department of Biological Sciences, University of Calgary, Calgary, AB, Canada aut Neil Emery R. Biology Department, Trent University, DNA Building, 2140 East Bank Drive, K9J, Peterborough, Ontario, Canada aut Reid David Department of Biological Sciences, University of Calgary, Calgary, AB, Canada aut Plant Growth Regulation Springer Netherlands 64/2(2011-06-01), 147-154 0167-6903 64:2<147 2011 64 10725 https://doi.org/10.1007/s10725-010-9549-7 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10725-010-9549-7 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Kurepin Leonid Department of Biological Sciences, University of Calgary, Calgary, AB, Canada aut NATIONALLICENCE 700 1- Walton Linda Department of Biological Sciences, University of Calgary, Calgary, AB, Canada aut NATIONALLICENCE 700 1- Pharis Richard Department of Biological Sciences, University of Calgary, Calgary, AB, Canada aut NATIONALLICENCE 700 1- Neil Emery R. Biology Department, Trent University, DNA Building, 2140 East Bank Drive, K9J, Peterborough, Ontario, Canada aut NATIONALLICENCE 700 1- Reid David Department of Biological Sciences, University of Calgary, Calgary, AB, Canada aut NATIONALLICENCE 773 0- Plant Growth Regulation Springer Netherlands 64/2(2011-06-01), 147-154 0167-6903 64:2<147 2011 64 10725 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer