Overexpression of Glutathione Reductase in Cotton Does Not Alter Emergence Rates under Temperature Stress

Cotton (Gossypium hirsutum L.) seedlings are considered to be sensitive to temperature stress. The exposure of plants to high and low temperatures can result in the production of reactive oxygen species that contribute to diminished plant performance. Plants have mechanisms that metabolize oxidants into less harmful chemicals, and enhancement of antioxidant metabolism has been shown to be benefi cial to plants exposed to acute oxidative stresses. Transgenic overexpression of glutathione reductase (GR) in cotton could result in faster seedling emergence at nonoptimal temperatures. Transgenic GR and 5 nontransgenic cotton lines were planted at four dates in the fi eld in Lubbock, TX, and in constant temperature growth boxes. The temperatures in the fi eld were typical for the cotton planting period in the region, and in growth boxes ranged from 15 to 45°C. Emergence rates were determined for all lines, and the activity of GR and the levels of malondialdehyde in the cotyledons were monitored to verify altered enzyme activity and to detect differences in oxidative damage, respectively. Enhancement of GR activity did not improve emergence or reduce oxidative damage. It is concluded that GR activity did not limit emergence. J.R. Mahan, D.C. Gitz, III, and P.R. Payton, USDA-ARS, Plant Stress and Water Conservation Lab., 3810 4th St., Lubbock, TX, 79415; R. Allen, Texas Tech Univ., Dep. of Biological Sciences, Lubbock, TX 79409. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable. Received 8 Feb. 2008. *Corresponding author ( [email protected]). Abbreviations: C312, Coker 312; DOY, day of year; DRR, De Ridder Red Leaf; FM800, Fibermax 800; FM989, Fibermax 989; GR, glutathione reductase; GR+, glutathione reductase overexpressed cotton; GSSG, oxidized glutathione; MDA, malondialdehyde; PM2326, Paymaster 2326; ROS, reactive oxygen species; TBA, thiobarbituric acid. Published in Crop Sci. 49:272–280 (2009). doi: 10.2135/cropsci2008.02.0085 © Crop Science Society of America 677 S. Segoe Rd., Madison, WI 53711 USA All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher.