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Subject: Agricultural Biochemistry × Author: Rashpal Kumar × End date: 2013 × Start date: 2011 × Type: Thesis × Thesis Type: M.Sc ×
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    EFFECT OF PUTRESCINE AND HIGH TEMPERATURE ON THE ANTIOXIDANT ENZYMES IN WHEAT (Triticum aestivum L)
    (Punjab Agricultural University, Ludhiana, 2013) Rashpal Kumar
    Effect of putrescine (Put) and high temperature (HT) on the responses of wheat (Triticum aestivum L) seedlings or developing grains was studied in six wheat cultivars (PBW 343, C 273, C 306, PBW 550, PBW 621 and HD 2967) raised in the laboratory (25o or 32oC) in petri dishes for seven days or in the field under normal (Nov, 2011) and late (Dec, 2011) planting conditions. High temperature significantly reduced root/shoot lengths and dry weights of all the six cultivars, whereas Put ameliorated this effect by increasing these attributes. C 306 and C 273 showed higher root/shoot lengths and dry weights over PBW 550, PBW 621. High temperature significantly increased the activities of ascorbate peroxidase (APX), guaiacol peroxidase (GPX), superoxide dismutase (SOD) and catalase (CAT) in correspondence with an increased membrane injury index (MII) and contents of thiobarbituric acid reactive substances (TBARs) and H2O2. Application of Put under HT further elevated activities of these enzymes whereas MII and contents of TBARs, H2O2 were reduced. Infact, Put treated seedlings performed better in terms of antioxidant response under HT than seedlings in absence. Developing grains at mid milky (15 DPA) and at maturity stages (30 DPA) also showed higher activities of APX, GPX, CAT and SOD in C 306 than PBW 343 both under normal and late sown conditions. C 306 showed lower MII, TBARs content and DAO, PAO activities over PBW 343. Similar to seedlings, activities of these enzymes in grains were enhanced with Put whereas the contents of MII, TBARs content, DAO and PAO activities were reduced in both the cultivars at 15 and 30 days post anthesis. Substantial higher activities of these enzymes in the developing grain at HT revealed their significant role in scavenging free radical and thus overcoming oxidative stress. Various marpho-physiological parameters like plant height, peduncle length, 1000 grain weight and number of grains per ear were decreased in late sown crop. However, Put application under HT stress increased these parameters. Overall, it appears that upregulation of the antioxidant system b y Put in wheat cultivars contributes to better protection and membrane integrity in root, shoot and grains against HT through reduced MII and TBARs contents.