Antioxidative responses in roots and shoots of creeping bentgrass under high temperature: effects of nitrogen and cytokinin.
It has been previously reported that either nitrogen (N) or cytokinin (CK) applications can alleviate heat stress injury on creeping bentgrass, with some studies reporting enhanced antioxidant metabolism being related to stress protection. The objective of this research was to investigate the simultaneous effects of CK and N on the antioxidant enzyme activity and isoforms of heat stressed creeping bentgrass. 'L-93' creeping bentgrass treated with three rates of CK (trans-zeatin riboside, tZR, 0, 10 and 100μM, designated by CK0, 10, and 100) and two nitrogen rates (2.5 and 7.5kgNha(-1) biweekly, low and high N) in a complete factorial arrangement was maintained in a 38/28°C (day/night) growth chamber for 28d and then harvested. Grass grown at high N (averaged across CK rates) had higher O(2)(-) production, H(2)O(2) concentration, and malondialdehyde content in roots. The activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), and guaiacol peroxidase (POD) in roots were enhanced 19%, 22%, and 24%, respectively, by high N relative to low N. Twenty-eight days of heat stress resulted in either the development of new isoforms or enhanced isoform intensities of SOD, APX, and POD in roots compared to plant responses prior to heat stress. However, no apparent differences were observed across treatments. Both SOD and POD showed different isoform patterns between roots and shoots, suggesting the function of these isoforms could be tissue specific. Interestingly, no CK effects on these antioxidant parameters were found in this experiment. These results demonstrate the impacts of N on antioxidant metabolism of creeping bentgrass under heat stress with some differences between roots and shoots, but no simultaneous impacts of CK and N.
Department of Crop and Soil Environmental Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA. kehua@vt.edu
Kehua
K
Wang
Xunzhong
X
Zhang
Erik
E
Ervin
D031703:Agrostis / Q000187:drug effects / Q000502:physiology*; D000975:Antioxidants / Q000378:metabolism*; D060387:Ascorbate Peroxidases / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D003583:Cytokinins / Q000378:metabolism / Q000494:pharmacology*; D006358:Hot Temperature; D006861:Hydrogen Peroxide / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism / Q000494:pharmacology*; D009195:Peroxidase / Q000378:metabolism; D010937:Plant Growth Regulators / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism; D018520:Plant Shoots / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism
D000975:Antioxidants; D003583:Cytokinins; D010937:Plant Growth Regulators; D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide; C121048:guaiacol peroxidase; D060387:Ascorbate Peroxidases; D002374:Catalase; D009195:Peroxidase; D013482:Superoxide Dismutase; D009584:Nitrogen