Tropical Plant Pathology
URI permanente para esta coleçãohttps://thoth.dti.ufv.br/handle/123456789/13106
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Resultados da Pesquisa
Item Defense responses to Meloidogyne exigua in resistant coffee cultivar and non-host plant(Sociedade Brasileira de Fitopatologia, 2013) Silva, Rodrigo V.; Oliveira, Rosângela D.L.; Ferreira, Patrícia S.; Ferreira, Aline O.; Rodrigues, Fabrício A.The resistance of coffee plants to Meloidogyne exigua is conferred by the gene Mex-1. However, the mechanisms of resistance still need to be clarified. Therefore, the penetration, development and reproduction of two populations of M. exigua (M1, isolated from the coffee plant and M2, from rubber tree) in susceptible (Coffea arabica ‘Catuai’) and resistant (C. canephora ‘Apoatã’) cultivars were studied. A greater quantity of J2 from M1 penetrated the susceptible cultivar, but there was no difference between the cultivars for M2. Although the resistant coffee cultivar formed some galls, the nematode did not reproduce. M2 did not induce the formation of galls or the production of eggs in either cultivars. Events related to hypersensitive reaction (HR) were observed as well as other defense responses of the coffee cultivar against M. exigua, which inhibited the formation of the feeding site, provoked emigration of the J2 and delayed or inhibited development and reproduction. The response of the non-host plant was more effective, because it did not allow development of the nematode or, consequently, its reproduction. It was concluded that the coffee cultivar’s resistance to M. exigua is not restricted to HR, but rather to a set of defense responses, both constitutive and induced, expressed after nematode penetration, especially phenolic-like compounds.Item Chlorogenic acid levels in leaves of coffee plants supplied with silicon and infected by Hemileia vastatrix(Sociedade Brasileira de Fitopatologia, 2011) Rodrigues, Fabrício A.; Carré-Missio, Vivian; Jham, Gulab N.; Berhow, Mark; Schurt, Daniel A.Rust, caused by Hemileia vastatrix, is the main disease that decreases coffee production in Brazil. New and enhanced methods to reduce rust intensity that can be integrated with modern genetic and chemical approaches need to be investigated. Considering that many plant species supplied with silicon (Si) show increased resistance to several pathogens, this study examined the possible effect of this element in increasing chlorogenic acid (CA) concentrations in coffee leaves and, consequently, increasing the level of resistance to rust. Plants (cv. “Catuaí Vermelho IAC 44”) were inoculated with H. vastatrix after growing for 35 days in a hydroponic culture amended with 0 (-Si) or 2 (+Si) mM Si. Concentration of Si in leaf tissues was of 0.36 and 0.42 dag/kg for -Si and +Si treatments, respectively, but without a statistically significant difference. The area under rust progress curve was 154.5 and 119.4 for -Si and +Si treatments, respectively, but without significant statistical difference. For non-inoculated plants, the concentrations of total CA and caffeoyl-quinic acid (CQA) compounds (diCQA) were similar between -Si and +Si treatments. Even though there was an increase of 236.4 and 257.1%, respectively, for total CA and diCQA for +Si when compared to -Si treatment at 30 days after inoculation with H. vastatrix, reduction on rust severity was not obtained once the fungus had already colonized the leaf tissues. Therefore, regardless of the increase in the concentrations of chlorogenic acid on leaves, coffee resistance to H. vastatrix infection was not potentialized by Si.Item Efeito da aplicação foliar de silício na resistência à ferrugem e na potencialização da atividade de enzimas de defesa em cafeeiro(Sociedade Brasileira de Fitopatologia, 2009) Pereira, Sandra C.; Rodrigues, Fabrício A.; Carré-Missio, Vivian; Oliveira, Maria Goreti A.; Zambolim, LaércioA principal medida de controle da ferrugem do cafeeiro, causada por Hemileia vastatrix, é o uso de fungicidas. O fornecimento de silício (Si) às plantas é uma estratégia de controle interessante considerando o potencial desse elemento em aumentar a resistência de várias espécies de plantas à patógenos. Este trabalho avaliou o efeito da aplicação foliar do Si na redução da severidade da ferrugem e na possível potencialização da atividade de seis enzimas relacionadas com a resistência de plantas à patógenos. Mudas de café (cultivar Catuaí Vermelho 44) foram pulverizadas com água destilada, solução de silicato de potássio (KSi) (35 g/L, pH 10,5), KSi (35 g/L, pH 5,5) e solução de acibenzolar-S-metil (ASM) (200 μg/L) 24 horas antes da inoculação. Não houve diferença significativa entre os tratamentos para os teores foliares de Si e potássio. A severidade foi significativamente maior em mudas pulverizadas com água em relação aos demais tratamentos. O ASM reduziu significativamente a severidade em 70% em relação à aplicação de água. A aplicação de soluções de KSi, independente do pH, também reduziu a severidade. O ASM foi eficiente em aumentar a atividade de quitinases e β-1,3-glucanases, porém a aplicação de KSi, independente do pH da solução, foi ineficiente em potencializar a atividade das seis enzimas estudadas, embora tenha reduzido a severidade.