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20153
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Subject: Biochemistry × End date: 2015 × Start date: 2015 × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Study of grain carbon metabolism in relation to nitrogen use efficiency in wheat
    (PAU, 2015) Kaur, Balraj; Asthir, Bavita
    The present study was conducted to evaluate the effect of application of nitrogen (N) under field conditions on six wheat genotypes (GLU 1356, HD 2967, PBW 621, PBW 636, PBW 550 and PBW 343) at three levels of N optimal N dose (120 Kg N/ha), sub-optimal N dose (90 Kg N/ha) and supra-optimal N dose (150 Kg N/ha). Enzymes involved in N metabolism (viz. nitrate reductase , glutamine synthetase, glutamate synthase, glutamate oxaloacetate transaminase and glutamate pyruvate transaminase); and carbon metabolism [viz. sucrose synthase (synthesis), sucrose phosphate synthase, Sucrose synthase cleavage, acid invertase, neutral invertase, phosphoenolpyruvate carboxylase (PEPC), malate dehydrogenase (MDH) and isocitrate dehydrogenase (ICDH)] along with various metabolites were studied in roots, flag leaf and grains at different developmental stages. Results indicated that supra-optimal dose upregulated N and carbon metabolizing enzymes, whereas sub-optimal N dose indicated that aminotransferases enhanced the protein content while increased activities of invertases provide carbon skeleton for amino acid. Apparently, PEPC, ICDH and MDH resulted in assimilating ammonium ions thereby reducing its toxicity. Interestingly at sub-optimal N dose, higher activity of polyamine catabolizing enzymes results in speeding up oxidation of various polyamines to cope up with N deficiency in plant. Putrescine was found to be higher at early stage whereas spermidine and spermine were found to be higher towards mature stages of grain indicating the role of putrescine in grain filling process. Using, hydroponic culture technique in lab providing N sources viz. 4mM KNO3, NH4Cl and NH4NO3 for 12 days, the size of shoot and root system decreased significantly when plants were supplied with NH4Cl as exclusive N source. NH4Cl speed up amino acid content by elevated glutamate dehydrogenase, aminotransferases and PEPC activities and thereby decreasing NH4+ toxicity. Whereas under NH4NO3 treatment, N and carbon metabolism were elevated as compared to NH4Cl and control conditions but less than KNO3 source indicating inhibition of NH4+ toxicity by NO3- uptake. Tiller culturing technique also supported the above findings of grain filling processes, soluble sugars/starch were strongly correlated to invertase activities whereas proteins to aminotransferases. GLU 1356, HD 2967 showed highest value of nitrogen use efficiency followed by PBW 621, PBW 636, PBW 550 and PBW 343, therefore, categorized as N efficient genotypes.
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    ThesisItemOpen Access
    Purification and characterization of protease inhibitors from pigeonpea (Cajanus cajan L.) and their interaction with Helicoverpa armigera (Hubner) proteases
    (PAU, 2015) Grover, Sheetanshu; Grewal, Satvir Kaur
    Ten pigeonpea genotypes were assessed for trypsin inhibitor (TI) status in leaves, flowers, pod walls, green seeds and mature seeds. TI interaction with purified Helicoverpa armigera trypsin was studied. Trypsin purified from H. armigera gut using Sephadex G-100 column chromatography was ~18.8 kDa, with optimum temperature and pH 50 °C and 11, respectively. TI content in leaves, flowers, pod walls and seeds increased with infestation ranging from 11 trypsin inhibitor units/g (TIU/g) to 33 TIU/g; 19 TIU/g to 38 TIU/g; 18 TIU/g to 55 TIU/g and 58 TIU/g to 181 TIU/g, respectively. Per cent inhibition of H. armigera gut proteases ranged from 19 to 43 % with infested leaves, 20 to ~ 51 % with flowers and 25 to 36 % with seeds. TI content in pigeonpea mature seeds varied from 147.75 TIU/g (in AL 201) to 177.85 TIU/g (AL 1495). SDS-PAGE of seed extracts revealed proteins of molecular weight ranging from 15.6 kDa to 98.5 kDa. Using gelatin SDS-PAGE, six different TIs with bovine trypsin were identified and four of them (Rm 0.39, 0.78, 0.84 and 0.93) were present in all the genotypes. Five H. armigera protease inhibitors (PIs) were detected using the gelatin SDS-PAGE. The purified inhibitor from mature seeds corresponds to ~17.3 kDa, with optimum temperature 50 ºC. pH optima for genotypes AL 1770 and AL 1677 were neutral (7.0) and alkaline (12.0). For AL 1753, pH optima were 7.0 and 10.0. Purified TI from pigeonpea inhibited purified trypsin nearly competitively.
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    Screening and biochemical analyses for salinity tolerance in cotton
    (PAU, 2015) malhotra, Hina; Sangha, Manjeet Kaur
    Cotton, an important cash crop, is moderately tolerant to salinity (7.7 dS/m) and new accessions need to be screened and evaluated w.r.t biochemicals for salt tolerance. In the present study, 32 G. rboreum and 109 G. hirsutum genotypes along with national check (G. herbaceum RAHS 14) were screened ydroponically at EC 18 and 21 dS/m using wooden frame and plastic tray design. Survival ercentage and growth parameter data were recorded at 15 DAG (days after germination). Six arboreum (FDK 242, FDK 194, FDK 226, LD 949, LD 1037 and FDK 231) and twelve hirsutum (LH 2076, LH 2357, LH 2373, F 2164, F 2228, F 2282, F 2381, F 2440, F 2581, F 2583, F 2631, FMDH 15) genotypes outperformed RAHS 14 while thirteen (LH 2108, LH 2312, LH 2533, F 846, F 2454, F 2468, F 2488, F 2493, F 2501, F 2630, F 2636, F 2639, F 2641) were at p ar with the check at 21 dS/m. The performance of seven selected genotypes viz. four G. hirsutum; F 846, LH 2076, LH 2108 (tolerant (T)), F2560 (susceptible (S)) and three G. arboreum; LD 949, FDK 226 (T) and FDK 253 (S), was evaluated in soil also. LD 949 and F 846 recorded least reduction in germination. Growth parameters (shoot length and weight) and leaf area recorded at different DAG revealed better performance of LD 949, FDK 226, F 846, LH 2076 and LH 2108 than FDK 253 and F 2560. NaCl did not affect chlorophyll content and PS II activity in all the tested genotypes. Successive increase in Na + and decrease in K + and K + /Na + was recorded in roots and leaves of all the genotypes with increasing NaCl concentration. The better performing five genotypes recorded greater Na + accumulation than FDK 253 and F 2560. Salinity stress enhanced activities of superoxide dismutase, peroxidase, catalase, ascorbate peroxidase and glutathione reductase in the T genotypes. Proline content increased in all the tested genotypes while glycine betaine was recorded to be highest in LD 949. Soluble sugar content increased maximum in F 846 and FDK 226. However, no increase in reducing sugars was recorded in all the arboreum genotypes. The highest concentration of phenolic and ascorbic acid in the leaf extracts were registered for LD 949 and FDK 226. G. hirsutum genotype F 2560 exhibited less increase in proline, glycine betaine, vitamin C, total and reducing sugar content than the other genotypes but its phenolic content was recorded to be highest. The antioxidant status revealed that better growth of genotypes LD 949, FDK 226, F 846, LH 2076 and LH 2108 can be attributed to the effective antioxidative defense mechanism. The soil experiment corroborated the hydroponic results and confirmed that FDK 226, LD 949, F 846, LH 2076 and LH 2108 exhibited higher adaptive potential under salinity stress and may be exploited for the development of salt tolerant cultivars as well as mapping populations for mapping QTL governing salt tolerance.