Possíveis efeitos do silício no desenvolvimento da estria bacteriana do trigo

• Ano de defesa: 2008
• Autor(a) principal: Silva, Ivanete Tonole da
• Orientador(a): Oliveira, José Rogério de
• Banca de defesa: Moura, Andrea Bittencourt , Teixeira, Hudson
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Fitopatologia
• Departamento: Etiologia; Epidemiologia; Controle
• País: BR
• Palavras-chave em Português: Silício; Estria bacteriana; Trigo
• Palavras-chave em Inglês: Silicon; Bacterial streak; Wheat
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOSSANIDADE::FITOPATOLOGIA
• Link de acesso: http://locus.ufv.br/handle/123456789/1056

The present study evaluated the effects of silicon (Si) on wheat black chaff development, caused by Xanthomonas translucens pv. undulosa (Xtu), and the defense mechanisms enhanced by this element by microscopy and biologic markers. The experiments were conducted in greenhouse in a completely randomized design with four replications. Wheat plants (cultivar BR18) were grown on plastic pots containing 1 kg of soil with the addition of 0.387 g of calcium carbonate (treatment without Si) or 0.3 g Si (treatment with Si) using wollastonite as the source of this element. The essays were conducted in two steps. In the first, wheat plants between 37 and 41 days after seedling (d.a.s) were inoculated with a bacterial suspension (OD540 = 0.05 or OD540 = 0.1) to evaluate the following variables: incubation period (IP), latent period (LP), bacterial population dynamics in plant (BDP), electrolyte leakage (EE) and disease severity. The experiment was conducted once. In the second step, wheat plants between 37 and 41 d.a.s were inoculated with bacterial suspension (OD540 = 0.1) to quantify the activity of the enzymes chitinases (QUI), peroxydases (POX) and polyphenoloxydases (PFO). The concentration of total soluble phenolics (TSP) and lignin thioglycolic acid derivatives (LTAD) were also determined. Samples for microscopic analyses and also for Si and calcium concentration on leaves were collected for both assay steps. Foliar contents only differed significantly for Si variant. The variables IP, LP, BDP, EE, and disease severity did not differ significantly between plants supplied or not with Si. There were significant and punctual differences between plants supplied or not with Si regarding the enzymatic activity of POX, PFO and LTAD. Regarding the QUI activity, there were statistical differences between plants supplied or not with Si throughout the entire evaluation period. In this case, wheat plants not supplied with Si and infected with Xtu showed the highest enzyme activity. Scanning eletron microscopy observations showed cuticle degradation and parenchyma tissue collapse in infected wheat leaf tissues. The observations from this study allowed to conclude that such structural injuries occurred as a result of Xtu infection. Silicon had not a great impact on enhance the mechanisms of resistance examined on this study.