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20164
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Subject: Biochemistry × End date: 2016 × Start date: 2016 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Expression profiling of iron homeostasis gene(s), and antioxidant system in rice (Oryza sativa L.)
    (CCSHAU, 2016) Saini, Ritu; Jain, Sunita
    In the present investigation, biochemical and molecular changes in root and shoot tissues of six rice varieties (Govind, Super, HKR120, Pusa1121, HBC19 and Palman579) differing in grain iron concentration (35- 400 μg/g) were studied in response to varied iron concentrations at vegetative and reproductive stages. Plants were grown in pots in the net house and treated twice with Yoshida solution containing different iron concentrations (0, 0.1 mM, 0.5 mM EDTA-Fe II). Fe content in roots, shoots and grains increased with increase in Fe concentration. Roots of HBC19 and Palman579 and lower and upper shoots of PUSA1121 contained higher iron. Highest iron in dehusked grains was recorded in Palman579 followed by HBC19, PUSA1121, HKR120, Super and Govind. Production of toxic super oxide radical (O2 - ) and hydrogen peroxide (H2O2) and lipid peroxidation (MDA), an indicator of cell membrane damage, enhanced in all the varieties with increase in Fe concentration and increase being higher in the low Fe (Govind and Super) than medium (HKR120 and PUSA1121) and high Fe content varieties (HBC19 and Palman579). Antioxidative metabolites’ contents (ascorbic acid and glutathione) and activities of antioxidative enzymes [super oxide dismutase (SOD), catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX) and glutathione reductase (GR)] invariably increased with increasing iron treatment in both root and shoot. The activities remained significantly low in the low grain Fe content varieties, Govind and Super, as compared to medium and high Fe varieties. A significant positive correlation was observed between the per cent change in H2O2 content and SOD, CAT and POX activities, between percent change in ascorbate and APX and between glutathione content and GR activities. Two SOD, one CAT, three POX and two APX isozymes were common to all six varieties. One more isozyme each of SOD and APX appeared only in medium and high iron varieties. One CAT, two POX and one APX isozymes had differential pattern with respect to varieties and iron treatments in both the tissues and stages while one isoform of SOD, POX and APX was unique to HBC19 shoots at 0.5 mM Fe treatment. Maximum grain yield was recorded at 0.1 mM iron concentration as compared to control and high iron treatment. Relative expression of genes involved in iron homeostasis [Nicotinamine synthase 1 (OsNAS1), Nicotinamine synthase 2 (OsNAS2), Nicotinamine synthase 3 (OsNAS3), Iron-regulated transporter 1 (OsIRT1) and Yellow stripe like 2 (OsYSL2)] was analyzed in Govind, PUSA1121 and Palman 579; expression of these genes except OsYSL2 was higher in root tissues of Govind. In the shoot tissues, expression of OsNAS1 and OsNAS2 was maximum in Govind while that of OsNAS3, OsYSL2 and OsIRT1 was more in PUSA1121 and Palman579. Expression of all the genes except OsYSL2 in root tissues was up-regulated with increase in iron concentration.
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    ThesisItemOpen Access
    Drought stress related biochemical changes in antioxidant metabolism and quality attributes in wheat (Triticum aestivum L.)
    (CCSHAU, 2016) Dommalapati, Sudhakara Rao; Madan, Shashi
    The present investigation was conducted to study the effect of drought stress on antioxidant and proline metabolism in leaves and developing grains of two wheat varieties viz. WH 1105 and WH 1025. Drought stress was imposed by giving pre-sowing irrigation only and samples were taken at seven days interval from 7th to 28th days after anthesis. The results showed that during grain development, activities of antioxidant enzymes viz. superoxide dismutase, catalase, peroxidase, ascorbate peroxidase and glutathione reductase increased more in WH 1025 under drought stress than WH 1105. Antioxidant metabolites such as ascorbate, glutathione, proline and hydrogen peroxide content increased under drought stress in leaves and developing grains while the carotenoid content decreased. The enhancement of antioxidant metabolites was also reflected in concomitant enhancement of total antioxidant activity. Isozyme pattern of superoxide dismutase, catalase, peroxidase and ascorbate peroxidase altered under drought stress with enhanced intensities in leaves and developing grains from 7th to 28th days after anthesis. Alteration in proline level under stress was due to changes in the activities of enzymes involved in proline metabolism. Proline synthesizing enzymes such as Δ1 pyrroline-5-carboxylate synthetase and Δ1 pyrroline-5-carboxylate reductase were also increased under drought stress; however proline degrading enzyme, proline oxidase activity decreased. Physiological parameters related to flag leaf membrane injury like lipoxygenase, malondialdehyde increased while leaf membrane stability, leaf lipids and total soluble protein content decreased under drought stress. Physiological parameters such as relative water content, osmotic potential, chlorophyll content and chlorophyll fluorescence gradually decreased under drought stress while canopy temperature increased. Quality parameters like grain appearance, hectolitre weight, grain hardness, crude fibre, total sugars and starch content decreased under drought stress, but sedimentation value, crude protein and gluten content increased. Phenological parameters like days to heading, days to anthesis, days to maturity and grain filling duration declined under drought stress. Yield attributes such as grain number per spike, grain weight per spike, test weight and grain yield per square meter decreased under the influence of drought stress. The reduction in physiological, biochemical, yield and grain quality traits was found to be more pronounced in WH 1105 in comparison to WH 1025. Drought susceptible index found to be less in WH 1025 than WH 1105.
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    ThesisItemOpen Access
    Role of Gibberellic Acid and Calcium Chloride in Ripening Related Biochemical Changes in Guava (Psidium guajava L.) Fruit
    (CCSHAU, 2016) Reena Devi; Jain, Veena
    During present investigations, guava fruits of cultivars L-49 and Hisar Surkha, harvested at IG, MG, T, R and OR stage were analyzed for various physico-chemical and biochemical parameters. TSS and sugars (total, reducing and non reducing) increased while fruit firmness and acidity decreased during ripening. Content of cell wall components viz. NDF, ADF, hemicellulose, cellulose, lignin, pectin and silica was maximum at MG stage and decreased thereafter. PME was maximally active at turning stage while PG and cellulase increased continuously. ROS indices viz. LOX activity, superoxide radical and H2O2 content increased progressively while the activities of ROS scavenging enzymes viz. SOD, CAT, POX, APX and GR and the content of ROS scavenging metabolites viz. ascorbate and glutathione increased initially but later on during ripening, a significant decline was observed. However, b-carotene content decreased throughout ripening. Ethylene evolution and ACC oxidase activity were maximum at turning stage. Pre-treatment of fruits with GA3 and CaCl2 caused significant inhibition of cell wall degrading enzymes, activation of ROS scavenging enzymes and reduction in ethylene evolution during storage. ACC oxidase and glutathione content were however, not affected by treatments. PG, purified 88 fold with 35 per cent recovery, was thermostable and a homodimer with Mr of 80 kDa. It exhibited Michaelis Menten kinetics with Km value of 0.14%. K+, Na+ and Fe3+ ions were found to be stimulatory. However, divalent ions Ca2+, Zn2+ and Mg2+ had inhibitory effect. The metal binding reagent EDTA and various low molecular weight polyols were found to be inhibitory. All reducing agents namely b-ME, DTT and cysteine activated PG.
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    ThesisItemOpen Access
    Effect of arbuscular mycorrhiza fungi on biochemical parameters in wheat (Triticum aestivum L.) under drought conditions
    (CCSHAU, 2016) Babita Rani; Madan, Shashi
    The present study was carried out to evaluate the effect of arbuscular mycorrhizal fungi (AMF) on the biochemical changes of two wheat varieties viz. WH 1025 and WH 1105. Plants of two wheat varieties were raised in earthen pots. Water stress was created by withholding irrigation at two growth stages (jointing and heading). In present study the effect of drought stress was observed on antioxidative system, nitrogen, phosphorous metabolizing enzymes, physiological, quality and yield parameters at jointing and heading stage. The results showed that under stress conditions, mycorrhizal inoculation significantly increased the relative water content, chlorophyll content and chlorophyll fluorescence but decreased the osmotic potential and electrolyte leakage in leaves of both the varieties at both the growth stages. The AMF colonized plants had significantly lower superoxide radical (O2 .-) hydrogen peroxide (H2O2) and malondialdehyde (MDA) content as compared to the uninoculated controls under water deficit conditions in leaves and roots of both the varieties. The activities of superoxide dismutase, catalase, peroxidase, ascorbate peroxidase and glutathione reductase enhaced at both growth stages in both the varieties under these conditions. However the higher activities were reported in WH 1025 under stress conditions. Contrarily, reduction in CAT activity was observed in leaves of WH 1105 at both the stages. Ascorbic acid and glutathione content were found to be increased in WH 1025, however decreased in WH 1105 under stress conditions. Further, increase in nitrogen and phosphorous metabolizing enzymes under stress conditions is in agreement with N, P, K levels at both the growth stages of WH 1025 and WH 1105 varieties. Quality parameters like moisture content and crude fiber content decreased whereas, sedimentation value, gluten, protein content and grain hardness increased under drought stress conditions however AMF inoculation did not play a significant role in quality traits at both the growth stages of both the varieties. Yield parameters like grain number per spike, grain weight, numbers of productive tillers and biomass per plant and grain yield decreased under drought stress while in AMF treated plants yield was more than untreated plants of both varieties. The reduction in physiological, biochemical, yield and grain quality traits was found to be more pronounced in WH 1105 in comparison to the WH 1025. These results demonstrated that the AMF could confer greater tolerance of WH 1025 variety to soil water deficit through an enhancement in their antioxidative defence system and thereby reducing the level of O2 .-, H2O2 and MDA content