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Thesis

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2016 - 20203
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Subject: Biotechnology × Start date: 2016 × Type: Thesis × Thesis Type: M.Sc ×
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    Molecular mapping of leaf rust and stripe rust resistance genes transferred from Aegilops speltoides to hexaploid wheat
    (Punjab Agricultural University, Ludhiana, 2020) Angoth, Sravan Kumar; Chhuneja, Parveen
    Leaf rust and stripe rust are most serious diseases of wheat worldwide. Utilization of resistance cultivars is an effective and economical method to reduce losses from devastating diseases. Aegilops speltoides with SS genome, has been reported to be a valuable source of resistance genes for leaf rust, stripe rust and stem rust. In present study, inheritance studies and molecular mapping of leaf rust and stripe rust resistance genes were undertaken. Stripe and leaf rust resistant accession of Ae. speltoides was crossed with T. durum cv. Aconchi89. F1 was treated with colchicine and an amphiploid was developed which was selfed 2-3 times to develop stable amphiploid. Aconchi89-Ae. speltoides acc. TA1784 amphiploid was crossed and backcrossed with PBW550 and stable BC2F4 introgression lines were developed. Disease resistant introgression line P33-15 was further crossed with PBW550 for mapping population. In F2 population, 161 plants were segregated in ratio of 3:1 for strip rust and in F2:3 populations, plant were segregated in 1:2:1 ratio for resistant and susceptible for leaf rust at adult plant stage. F3 population genotyping was done by dd-RAD-seq, involves cleaving DNA with two restriction enzymes Sph1 and Mluc1 and by using dDocent pipeline, TASSEL V5.0 raw data was processed for processing steps. SNP were identified between parental genotypes P33-15 and PBW550 and 2118 total SNPs were found be polymorphic which were used for linkage map construction. The chromosomes 1D having minimum and chromosome 3B having maximum number of SNPs. Complete linkage map encompassed a total linkage distance of 17875 cM with a SNP density of 0.12 SNPs/cM. With only 569 SNPs the D genome showed least coverage of 4468.48 cM with a density of 0.127 SNPs/cM. A-genome mapped 660 SNPs while B-genome mapped 824 SNPs. Linkage map was further used for mapping genes/QTL for stripe rust and leaf rust resistance using ICI mapping using BIP function. The phenotypic data of the F2 population and genotypic data of the F3 population were used for mapping the stripe rust resistance loci. The QTL mapping was conducted with LOD threshold of 4.0. Ae. speltoides leaf rust resistance gene was mapped on terminal end of short arm of chromosome 7B at a distance of 26cM from nearest SNP marker S7B_733831709. Overall, one gene each for leaf rust and stripe rust resistance have been introgressed from wild progenitor species Ae. speltoides into hexaploid wheat. A SNP based linkage map consisting of 2118 SNP markers has been developed. A major QTL for stripe rust resistance has been mapped on chromosome 3B and a major gene for leaf rust resistance has been mapped on wheat chromosome 7B. Linked markers can be used for transferring these genes to other wheat backgrounds.
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    Analysis of detoxification and phenolic metabolism mediated through nitric oxide and hydrogen peroxide under ABA and water stress in wheat
    (Punjab Agricultural University, Ludhiana, 2016) Rattanpreet Kaur; Vikramjit Kaur
    Two wheat cultivars PBW644 (drought tolerant) and PBW343 (drought sensitive) were compared under PEG/ABA for ROS/nitric oxide (NO)-regulation of antioxidant metabolism. Endogenous ROS/NO under ABA/PEG increased germination and growth, such effect was higher in PBW644. In PBW343, reduced growth under PEG was improved by exogenous ROS/NO. ABA/PEGupregulation of GPX and GST involved ROS/NO signalling which was similar in both cultivars under ABA but higher in PBW644 under PEG. PEG increase of acid protease was higher in PBW343 while of alkaline protease was higher in PBW644. ABA/PEG-upregulation of proteases involved ROS/NO-signalling. Redox state of glutathione under PEG/ABA involved ROS/NO signalling which was induced in PBW343 while in PBW644, it was induced when exogenous ROS/NO applied under ABA (high stress level). Increase of ROS/NO under ABA/PEG was signal, it was higher in PBW644. Such signals were increased by ROS/NO-signalling. Moreover, ROS/NO-signalling also decreased ROS under ABA/PEG. Oxidative toxicity was lesser in PBW644 under PEG, was reduced by ROS/NO signals in both cultivars. However, exogenous ROS/NO under ABA could also increase oxidative toxicity. Under PEG, PBW644 showed higher upregulation of cell wall peroxidase (CW-POX) while lesser soluble peroxidase (S-POX). However, under ABA, it showed higher levels of both CW-POX and S-POX. ROS/NO signals under PEG/ABA contributed to increase both types of POX in both cultivars. PEG increase of phenolics and ABA/PEG increase of lignin was higher in PBW644. Under PEG/ABA, ROS/NOsignalling increased phenolics and decreased lignin in PBW343 while in PBW644, it increased both in shoot while decreased both in root. PEG increased flavonoids. Under PEG/ABA, ROS/NO signals may increase flavonoids.
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    ThesisItemOpen Access
    Effect of nitrogen fertilization on rice grain quality and the biochemical composition of straw
    (Punjab Agricultural University, Ludhiana, 2016) Amandeep Kaur; Sharma, Neerja
    A field experiment was conducted to evaluate the effect of nitrogen fertilization on rice grain quality and the biochemical composition of straw. The main plots included nitrogen levels of 0, 90,120 and 150 kg ha-1 for non-basmati and 0, 40 and 60 kg ha-1 for basmati varieties, while the subplots included non-basmati varieties viz., PR 111, PR 122 and Pusa 44 and basmati varieties viz., Basmati 370 and Pusa Basmati 1509. In rice grain, crude protein content, head rice recovery and gel consistency were positively related with increase in nitrogen levels in both non-basmati and basmati varieties. Thousand grain weight of only the basmati varieties expressed similar response. However a negative relationship for amylose content and elongation ratio with increase in nitrogen fertilization in all the cultivars was observed. There is significant interaction between nitrogen levels and all physiochemical characters of the grain except alkali spreading value in all the cultivars. In rice straw, increase in the level of nitrogen fertilization increased the crude protein from 2.28 to 7.41% in nonbasmati and 5.16 to 6.28% (dry matter basis) in basmati varieties whereas the neutral detergent fibre, acid detergent fibre and cellulose content decreased in both non-basmati and basmati varieties. The straw hemicellulose, acid detergent lignin, silica, ash, crude fat, crude fibre and organic matter exhibited significant interaction with different nitrogen levels in both non-basmati and basmati varieties. Therefore, use of optimum nitrogen levels will improve the nutritional quality of grain for human consumption and straw as feed resource.