Plants under water deficit have a limited capacity for carbon fixation. Continued light absorption under drought stress may result in excessive energy that cannot be used for carbon fixation but may cause reduction of molecular oxygen, generating active oxygen species (AOS) such as singlet oxygen (1O2), superoxide (O2 .−), hydrogen peroxide (H2O2), and hydroxyl radicals (OH·) (Asada, 1999). These species can cause oxidative damage to lipids, nucleic acids, and proteins (Smirnoff, 1993). The production of AOS is not limited to drought stress and also occurs as a result of extremes in temperature (Mishra and Singhal, 1992; Schoner and Krause, 1990), high irradiance levels (Halliwell and Gutteridge, 1989a), disease (Apostol et al., 1989), and nutrient deficiency (Cakmak and Marschner, 1988).
Plants have developed an antioxidant defense system in response to the generation of AOS within plant tissues. The antioxidant defense system is comprised of enzymatic and nonenzymatic components that can be divided into two different types of repair mechanisms: 1) production of antioxidants or antioxidant enzymes that directly react with and scavenge AOS, including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD), and α tocopherol; and 2) production of enzymes that regenerate oxidized antioxidants such as glutathione, glutathione reductase, ascorbate, and ascorbate reductase (Smirnoff, 1993). Accumulation of AOS results in increased antioxidant enzyme activities, providing indirect evidence for the extent of generation of AOS and the importance of these enzymes in scavenging free radicals (Smirnoff, 1993).
Drought stress resistance has been associated with either maintenance or increase in antioxidant enzyme activity levels in various plant species (Fu and Huang, 2001; Price and Hendry, 1989; Tanaka et al., 1990; Zhang and Schmidt, 1999). Antioxidant enzyme activity levels have been positively related to drought resistance in some species (Bowler et al., 1992; Jagtap and Bhargava, 1995; Lascano et al., 2001; Price and Hendry, 1989). Levels of SOD and CAT were maintained for a greater duration of combined drought and heat stress for a drought-tolerant cultivar of kentucky bluegrass (Poa pratensis L.) compared with a drought-susceptible cultivar (Wang and Huang, 2004). Zhang and Schmidt (1999) also found that kentucky bluegrass plants exhibiting higher levels of antioxidant enzyme activities maintained better turf quality under drought stress.
Under conditions of severe plant stress, the production of AOS may exceed the scavenging capacity of the antioxidant defense system (van Breusegem et al., 1998). As a consequence, AOS can accumulate and cause cellular damage such as lipid peroxidation or the oxidation of phospholipids and other unsaturated lipids. Peroxidation results in the breakdown of lipids and membrane function by causing loss of fluidity, lipid crosslinking, and inactivation of membrane enzymes (Girotti, 1990). The extent of lipid peroxidation can be calculated by measurement of malondialdehyde (MDA) content, which is a secondary breakdown product of lipid peroxidation (Halliwell and Gutteridge, 1989b). MDA content is a commonly used measurement for assessing lipid peroxidation and oxidative damage in both leaves and roots (Queiroz et al., 1998; Zhou and Zhao, 2004), and its maintenance of low levels has been associated with increased drought stress resistance in many plant species (Lima et al., 2002; Moran et al., 1994; Sairam et al., 1998; Zhang and Kirkham, 1994).
Identifying and understanding the function of antioxidant defense mechanisms are important for developing drought-tolerant plants. Our previous studies have found that velvet bentgrass is more tolerant to drought stress than creeping bentgrass or colonial bentgrass as exhibited by higher turfgrass quality, leaf water content, and osmotic adjustment under drought stress (DaCosta and Huang, 2006a, 2006b). Whether bentgrass species variation in drought resistance is also associated with differences in antioxidant mechanisms is not well understood. The objectives of this study were to determine whether bentgrass species variation in drought resistance could be associated with differences in antioxidant enzyme levels in response to drought stress.
AndersonM.D.PrasadT.K.StewartC.R.1995Changes in isozyme profiles of catalase, peroxidase, and glutathione reductase during acclimation to chilling in mesocotyls of maize seedlingsPlant Physiol.10912471257
ApostolI.HeinsteinP.F.LowP.S.1989Rapid stimulation of an oxidative burst during elicitation of cultured plant cells: Role in defense and signal transductionPlant Physiol.90109116
AsadaK.1999The water-water cycle in chloroplasts: Scavenging of active oxygens and dissipation of excess photonsAnnu. Rev. Plant Physiol. Plant Mol. Biol.50601639
BarrsH.D.WeatherleyP.E.1962A re-examination of the relative turgidity technique for estimating water deficit in leavesAust. J. Biol. Sci.15413428
DaCostaM.HuangB.2006aMinimum water requirements for creeping, colonial, and velvet bentgrasses under fairway conditionsCrop Sci.468189
DaCostaM.HuangB.2006bOsmotic adjustment associated with variation in bentgrass tolerance to drought stressJ. Amer. Soc. Hort. Sci.131338344
DhindsaR.S.DhindsaP.P.ThorpeT.A.1981Leaf senescence: Correlation with increased levels of membrane permeability and lipid peroxidation, and decreased levels of superoxide dismutase and catalaseJ. Exp. Bot.3293101
FuJ.HuangB.2001Involvement of antioxidants and lipid peroxidation in the adaptation of two cool-season grasses to localized drought stressEnviron. Exp. Bot.45105114
HalliwellB.GutteridgeJ.M.C.1989aProtection against oxidants in biological systems: The super oxide theory of oxygen toxicity86123HalliwellB.GutteridgeJ.M.C.Free radicals in biology and medicineClarendon PressOxford, UK
HalliwellB.GutteridgeJ.M.C.1989bLipid peroxidation: A radical chain reaction188260HalliwellB.GutteridgeJ.M.C.Free radicals in biology and medicineClarendon PressOxford, UK
HeY.LiuY.ChenQ.BianA.ChenW.2001Comparison of the optimal pH for 4 antioxidant enzymes in the seedlings of tall fescue (Festuca arundinacea Schreb.) and kentucky bluegrass (Poa pratensis L.)J. Nanjing Agr. Univ.2414
HoaglandD.R.ArnonD.I.1950The water-culture method for growing plants without soil31California Agr. Expt. Sta. Circ. 347College of Agriculture University of CaliforniaBerkeley
JagtapV.BhargavaS.1995Variation in the antioxidant metabolism of drought tolerant and drought susceptible varieties of Sorghum bicolor (L.) Moench. exposed to high light, low water and high temperature stressJ. Plant Physiol.145195197
LascanoH.R.AntonicelliG.E.LunaC.M.MelchiorreM.N.GomezL.D.RaccaR.W.TrippiV.S.CasanoL.M.2001Antioxidant system response of different wheat cultivars under drought: Field and in vitro studiesAustral. J. Agr. Res.2810951102
LimaA.L.S.DaMattaF.M.PinheiroH.A.TotolaM.R.LoureiroM.E.2002Photochemical responses and oxidative stress in two clones of Coffea canephora under water deficit conditions. EnvironExp. Bot.47239247
LunaC.SeffinoL.G.AriasC.TaleisnikE.2000Oxidative stress indicators as selection tools for salt tolerance in Chloris gayana Plant Breed.119341345
MishraR.K.SinghalG.S.1992Function of photosynthesis apparatus of intact wheat leaves under high light and heat stress and its relationship with peroxidation of thylakoid lipidsPlant Physiol.9816
MoranJ.F.BecanaM.Iturbe-OrmaetxeI.FrechillaS.KlucasR.V.Aparicio-TejoP.1994Drought induces oxidative stress in pea plantsPlanta194346352
PriceA.H.HendryG.A.F.1989Stress and the role of activated oxygen scavengers and protective enzymes in plants subjected to droughtBiochem. Soc. Trans.17493494
QueirozC.G.S.AlonsoA.Mares-GuiaM.MagalhaesA.C.1998Chilling-induced changes in membrane fluidity and antioxidant enzyme activities in Coffea arabica L. rootsBiol. Plant.41403413
SairamR.K.SrivastavaG.C.SaxenaD.C.2000Increased antioxidant activity under elevated temperatures: A mechanism of heat stress tolerance in wheat genotypesBiol. Plant.43245251
SaruyamaH.TanidaM.1995Effect of chilling on activated oxygen-scavenging enzymes in low temperature-sensitive and tolerant cultivars of rice (Oryza sativa L.)Plant Sci.109105113
SchonerS.KrauseG.H.1990Protective systems against active oxygen species in spinach: Response to cold acclimation in excess lightPlanta180383389
StrasserR.J.SrivastavaA.Tsimilli-MichaelM.2000The fluorescence transient as a tool to characterize and screen photosynthetic samples445483YunusM.PathreU.MohantyP.Probing photosynthesis: Mechanisms regulation and adaptationTaylor and FrancisLondon
TanakaK.MasudaR.SugimatoT.OmasaK.SakasiT.1990Water deficiency-induced changes in the contents of defensive substances against active oxygen in spinach leavesAgr. Biol. Chem.5426292634
ZhangJ.KirkhamM.B.1994Drought-stress-induced changes in activities of superoxide dismutase, catalase, and peroxidase in wheat speciesPlant Cell Physiol.35785791
ZhangX.SchmidtR.E.1999Antioxidant response to hormone-containing product in kentucky bluegrass subjected to droughtCrop Sci.39545551
ZhouR.ZhaoH.2004Seasonal pattern of antioxidant enzyme system in the roots of perennial forage grasses grown in alpine habitat, related to freezing tolerancePhysiol. Plant.121399408