ANTIOXIDANT ENZYME AND PHOTOSYNTHESIS RESPONSES TO COLD ACCLIMATION IN TWO ZOYSIAGRASS CULTIVARS
Zoysiagrass (Zoysia spp.),a warm-season turfgrass genus,is subject to freezing damage in the U.S.transition zone and other similar climate regions,so it is important to attempt to understand mechanisms of cold acclimation and subsequent effects on freezing tolerance.This study was designed to investigate changes in zoysiagrass leaf antioxidant enzyme activity,abscisic acid (ABA) content,hydrogen peroxide (H2O2) content,and photosynthesis during zoysiagrass cold acclimation.Two zoysiagrass cultivars (‘Meyer’,cold tolerant; ‘Cavalier’,relatively cold sensitive) were subjected to cold acclimation (8oC day/4oC night) and a photosynthetically active radiation (PAR) of 250 μmol m–2 s-1 over a 10-h photoperiod for 21 d in a growth chamber.Meyer had lower levels of cell membrane lipid peroxidation and greater overall freezing tolerance (LT50 = -14.2 oC) than Cavalier (LT50 = -6.8 oC).Stolon superoxide dismutase (SOD),catalase (CAT) and ascorbate peroxidase (APX) activities declined from 0 to 7 d and then increased from 7 to 21 d of cold acclimation.Meyer had higher SOD and CAT activities relative to Cavalier during cold acclimation.Leaf ABA and H2O2 contents increased rapidly during early stage of cold acclimation (3 d) and may serve as signals for inducing antioxidant responses.Leaf net photosynthesis (Pn) and stomatal conductance dropped more rapidly in Meyer than Cavalier at 1 d of cold acclimation.The results suggest that rapid declines in Pn and stomatal conductance,along with increases in ABA and H2O2,during early stage of cold acclimation may trigger a cold-protective antioxidant response.Our results indicate the zoysiagrasses with greater upregulation of ABA and subsequent SOD and CAT activities during cold acclimation should have greater freezing tolerance.
antioxidant Cold acclimation lipid peroxidation photosynthesis zoysiagrass
Xunzhong Zhang E. H. Ervin R. E. Schmidt
Department of Cropand Soil Environmental Sciences,Virginia PolytechnicInstitute and State University,Blacksburg,VA 24061 USA
国际会议
The 12th International Turfgrass Research Conference(第十二届国际草坪学术大会)
北京
英文
437-443
2013-07-14（万方平台首次上网日期，不代表论文的发表时间）