Teses e Dissertações
URI permanente desta comunidadehttps://locus.ufv.br/handle/123456789/1
Teses e dissertações defendidas no contexto dos programas de pós graduação da Instituição.
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Item Physiological, biochemical, and molecular aspects of induced resistance in soybean against rust using a nitrogen-and calcium-polyphenols compound and a phosphite of nickel and potassium(Universidade Federal de Viçosa, 2023-10-25) Fontes, Bianca Apolônio; Rodrigues, Fabrício de Ávila; http://lattes.cnpq.br/9624787372310476Soybean rust (SR), caused by Phakopsora pachyrhizi, is an aggressive disease that severely reduces the production of soybean crops worldwide. The SR control has been done by spraying fungicides and using cultural practices (e.g., early sowing dates, early detection of the rust symptoms development, cultivars of early maturing, and 60 to 90 days without growing soybean). However, sustainable control methods are preferred nowadays. In this point of view, induced resistance using biotic and abiotic defense elicitors plays an important role in plant disease management. The present study investigated the potential of Cautha® [calcium (11.01%) and nitrogen (3.3%) complexed with polyphenols (10%)] and Blindage Ni® [potassium (20% K2O, 280 g/L), nickel (0.5% Ni, 7 g/L), and phosphorous acid (500 g/L)] in displaying biochemical, molecular, and physiological resistance mechanisms against P. pachyrhizi. In the first study, plants were sprayed with water (control) or Cautha® (referred to as induced resistance [IR] stimulus after that) and inoculated or non-inoculated with P. pachyrhizi. The germination of urediniospores was reduced by 26% in vitro at the same dose of IR stimulus used to spray soybean plants. The rust severity and area under the disease progress curve lowered by 41% (at 15 days after inoculation) and 27%, respectively, for IR stimulus-sprayed plants compared to water-sprayed plants. The IR stimulus treatment greatly reduced the cellular damage caused by P. pachyrhizi infection in soybean tissues, maintained a great content of photosynthetic pigments, enhanced activities of defense-related enzymes, and built a robust antioxidative metabolism compared with the control treatment. In the second study, the factors investigated were water (control) or Blindage Ni® (referred to as induced resistance [IR] stimulus after that) inoculated or non-inoculated with P. pachyrhizi. In vitro, the urediniospores germination was reduced by 99% by IR stimulus. The soybean rust severity and area under the disease progress curve was decreased by 73% (at 15 days after inoculation) and 74%, respectively, in IR stimulus-sprayed plants compared to water-sprayed plants. The infected plants sprayed with IR stimulus maintain the proper functionality of photosynthetic apparatus and a good concentration of pigments. In addition, this treatment reduced the damage and lipid peroxidation in plant tissue, up-regulated the expression of several defense-related genes in plants infected by P. pachirhizi, kept a great concentration of potassium and nickel in soybean tissues, and increased the concentrations of phenolics and lignin in contrast with the control plants. The results of the present study highlighted the positive role of both IR stimuli in activating defense mechanisms against P. pachyrhizi in soybean crop and reducing disease severity. Keywords: Soybean rust. Glycine max. Plant defense mechanisms. Management of plant disease.Item Nickel in the soybean resistance against Sclerotinia sclerotiorum infection(Universidade Federal de Viçosa, 2021-02-26) Fontes, Bianca Apolônio; Rodrigues, Fabrício Ávila; http://lattes.cnpq.br/9624787372310476White mold, caused by the fungus Sclerotinia sclerotiorum, is one of the most destructive diseases impacting soybean yield worldwide. Nickel (Ni) plays an essential role in the metabolism of higher plants because of its involvement in the catalytic process of several enzymes and as a constituent of many biomolecules. This study investigated the potential of spraying Ni to soybean plants to increase their resistance against white mold by accessing the photosynthetic performance (chlorophyll (Chl) a fluorescence parameters and photosynthetic pigments pools (chlorophylls a+b and carotenoids), the concentrations of malondialdehyde (MDA), total soluble phenolics (TSP), and lignin-thioglycolic acid (LTGA) derivatives as well the expression of genes encoding for phenylalanine ammonia-lyase (PAL1.1, PAL1.3, PAL2.1, and PAL3.1), chitinase (CHIA1), chalcone isomerase (CHI1B1), lipoxygenase (LOX7), metalloproteinase (MMP2), isochorismate synthase (ICS1 and ICS2), urease (URE), pathogenesis-related protein 1 (PR-1A), nitrate and nitrite reductase (NIR1-1 and INR-2), oxaloacetate acetylhydrolase (Oxalo), and an AP2/ERF type transcription factor (ERF3). The in vitro assay showed that Ni inhibited the mycelial growth of S. sclerotiorum. The higher foliar Ni concentration contributed to decrease white mold severity for Ni-sprayed plants which exhibited less MDA production, maintained great photosynthetic pigments concentration, and had their photosynthetic apparatus much more preserved than the plants non-sprayed with Ni. High concentrations of TSP and LTGA derivatives linked to higher expression of CHI1B1, PAL1.3, PAL2.1, PAL3.1, and PR-1A for Ni-sprayed plants contributed to their resistance against the white mold. Based on the present study results, it is plausible to conclude the potential of using Ni to enhance the resistance of soybean against white mold in the context of a more sustainable agriculture that prizes the mineral nutrition of plants. Keywords: Glycine max. Aternative Disease Control. Fungal Infection. Host defense Responses. Photosynthesis. Plant nutrition.