Variability in enzymatic and non enzymatic antioxidants in wheat (Triticum aestivum L.) genotypes

Variability in enzymatic and non enzymatic antioxidants could be useful for breeding genotypes tolerant to different abiotic stresses. The objective of present study was to determine the variability in enzymatic and non enzymatic antioxidants in wheat at three different stages of development including leaves of vegetative stage, flag leaf stage after 5 days of anthesis and in mature grains. Forty wheat genotypes including 10 commercial cultivars, 5 rainfed cultivars, 17 advanced breeding lines and 8 Australian cultivars were raised under irrigated conditions. At vegetative stage, high activity of superoxide dismutase (SOD), peroxidase (POX), glutathione reductase (GR) and ascorbate peroxidase (APX) and low hydrogen peroxide (H₂O₂) content was observed in many of the advanced breeding lines, while high proline and low malondialdehyde (MDA) content was observed in many commercial cultivars. In flag leaf after 5 days of anthesis higher activity of SOD and APX was observed in many of rain-fed cultivars; many commercial cultivars showed high activity of POX and GR while low H₂O₂ content was observed in many of Australian cultivars. Ruby, Binnu and Datatine have low H₂O₂ and MDA content so they could be used for studying tolerance towards different types of abiotic stresses. PBW 550 showed high antioxidant activity in leaves during vegetative and flag leaf stage, it could be worthwhile to study the performance of this cultivar under different abiotic stresses. Variability was also observed in mature grains of different wheat genotypes. In mature grains high proline content was observed in many of rain-fed cultivars while less GR, CAT and APX activity was observed in many of Australian genotypes. Mature grains of wheat genotypes PBW 644, PBW542, DBW 16, DBW 17, WH 1021, PBW 676, BWL 73 and PBW 175 have high activity of APX, GR and some have high proline content. In general genotypes with high enzymatic antioxidants and low H₂O₂ and MDA content may be useful for studying tolerance towards different abiotic stresses. Genotypes with high antioxidants were identified for possible use in wheat breeding programme.