title: Changes during leaf expansion of ΦPSII temperature optima in Gossypium hirsutum are associated with the degree of fatty acid lipid saturation.
abstract: In this project, we hypothesize that cotton (Gossypium hirsutum) leaf temperature and the responses of leaf photosynthesis to temperature will change as the leaves expand and that differences between young and mature leaves will be associated with the proportion of saturated fatty acids in thylakoid and other membrane lipids. To that end, we studied main stem leaves obtained from plants growing in a temperature controlled greenhouse and at different times in the field season. We found that young leaves (∼5d old) had higher mid day temperatures, lower stomatal conductance and higher thermal optima as measured by ΦPSII temperature curves than did more mature leaves (∼13d old). Young leaves also had significant differences in fatty acid saturation with the warmer, young leaves having a higher proportion of palmitic acid (16:0) and lower linoleic acid (18:3) in total lipid extracts and higher 16:0 and lower palmitoleic acid (16:1) in the chloroplast membrane phosphoglycerides, digalactosyldiacylglycerol (in the greenhouse) and phosphatidylglycerol when compared with cooler, more mature leaves. Later in the growing season, leaf temperature, stomatal conductance and ΦPSII temperature curves for young and more mature leaves were similar and the proportion of 16:0 fatty acids decreased and 16:1 increased in phosphatidylglycerol. We conclude that changes in temperature as cotton leaves expand leads to alterations in the fatty acid composition of thylakoid and other membranes and, consequently, influence photosynthesis/temperature responses.
authors.affiliation: Department of Biology, University of Central Arkansas, Conway, AR 72035, USA.
authors.forename: Trent D
authors.initials: TD
authors.lastname: Hall
authors.affiliation: Department of Biology, University of Central Arkansas, Conway, AR 72035, USA.
authors.forename: Daryl R
authors.initials: DR
authors.lastname: Chastain
authors.affiliation: Center for Plant Lipid Research, Department of Biological Sciences, University of North Texas, Denton, TX 76203, USA.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Horn
authors.affiliation: Center for Plant Lipid Research, Department of Biological Sciences, University of North Texas, Denton, TX 76203, USA.
authors.forename: Kent D
authors.initials: KD
authors.lastname: Chapman
authors.affiliation: Department of Biology, University of Central Arkansas, Conway, AR 72035, USA. Electronic address: johnc@uca.edu.
authors.forename: John S
authors.initials: JS
authors.lastname: Choinski
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D002734:Chlorophyll / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism; D002940:Circadian Rhythm; D005227:Fatty Acids / Q000302:isolation & purification / Q000378:metabolism*; D005453:Fluorescence; D003368:Gossypium / Q000502:physiology* / Q000528:radiation effects; D008027:Light; D019787:Linoleic Acid / Q000302:isolation & purification / Q000378:metabolism; D019308:Palmitic Acid / Q000302:isolation & purification / Q000378:metabolism; D010788:Photosynthesis / Q000502:physiology*; D045332:Photosystem II Protein Complex / Q000502:physiology*; D018515:Plant Leaves / Q000502:physiology / Q000528:radiation effects; D054046:Plant Stomata / Q000502:physiology / Q000528:radiation effects; D018526:Plant Transpiration; D011891:Rain; D012621:Seasons; D013696:Temperature
chemical_list: D005227:Fatty Acids; D045332:Photosystem II Protein Complex; D002734:Chlorophyll; D019308:Palmitic Acid; D019787:Linoleic Acid
keywords: Chlorophyll fluorescence; Fatty acid saturation; Gossypium hirsutum; Leaf expansion; Photosynthetic thermotolerance