Preservação do inóculo de Plasmodiophora brassicae utilizando o método de congelamento
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Data
2009-02-01
Autores
Cruz, Juliana Cristina Sodário
Souza, Nilton Luiz de [UNESP]
Padovani, Carlos Roberto [UNESP]
Furtado, Edson Luiz [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Grupo Paulista de Fitopatologia
Resumo
A preservação das estruturas de resistência de Plasmodiophora brassicae, em condições laboratoriais, é dificultada pelo fato de se tratar de um parasita obrigatório. O método de congelamento, utilizando freezer, comum foi testado com o objetivo de viabilizar a sobrevivência e a preservação de suas características infectivas. Raízes de diferentes brássicas, naturalmente infectadas por P. brassicae, contendo sintomas típicos de hérnia, de uma mesma propriedade localizada no município de Pardinho, Estado de São Paulo, foram coletadas em diferentes épocas e imediatamente congeladas, em freezer, a aproximadamente -20ºC. Os tratamentos foram divididos da seguinte maneira: T1: hérnias congeladas por 389 dias (rúcula); T2: hérnias congeladas por 242 dias (brócolis); T3: hérnias congeladas por 21 dias (couve chinesa) e T4: testemunha (sem inóculo). Os testes de patogenicidade, após diferentes períodos de armazenamento, foram realizados em condições de casa de vegetação (25±2ºC). Cada planta de uma variedade suscetível de couve-chinesa (Pak choi) foi inoculada com 2mL da suspensão de esporos de cada tratamento, na concentração de 10(7) esporos.mL-1. Cada tratamento contou com seis repetições distribuídas em blocos ao acaso. Passadas cinco semanas após a inoculação, as raízes das plantas foram lavadas e avaliadas. Houve diferença significativa entre os tratamentos. Os materiais congelados, entre 21 a 242 dias preservaram suas características infectivas, mostrando que o método de congelamento em freezer, nesse período, pode ser uma boa opção para a preservação das estruturas de resistência deste patógeno.
The preservation of Plasmodiophora brassicae resistance structures under laboratory conditions is difficult since this is an obligate parasite. The freezing method using an ordinary household freezer was tested to ensure the pathogen's survival and the preservation of its infective traits. Roots of different brassica species naturally infected by P. brassicae, showing typical clubroot symptoms, sampled in the same farm, located in the Pardinho County, State of São Paulo, were collected during different seasons and were immediately frozen at approximately 20ºC. The treatments were divided as follows: T1: clubroots frozen for 389 days (arugula); T2: clubroots frozen for 242 days (broccoli); T3: clubroots frozen for 21 days (Chinese cabbage), and T4: control (without inoculum). The pathogenicity tests were conducted under greenhouse conditions (25±2ºC). Each plant of the susceptible variety of Chinese cabbage (Pak choi) was inoculated with 2mL of a spore suspension of each treatment at a concentration of 10(7) spores.mL-1. Each treatment consisted of six replicates distributed in random blocks. The roots of plants were washed and evaluated five weeks after inoculation. There were significant differences between treatments. The frozen materials preserved their infective traits over a period of 21 to 242 days, demonstrating that the freezing method could be an option to preserve the resistance structures of this pathogen.
The preservation of Plasmodiophora brassicae resistance structures under laboratory conditions is difficult since this is an obligate parasite. The freezing method using an ordinary household freezer was tested to ensure the pathogen's survival and the preservation of its infective traits. Roots of different brassica species naturally infected by P. brassicae, showing typical clubroot symptoms, sampled in the same farm, located in the Pardinho County, State of São Paulo, were collected during different seasons and were immediately frozen at approximately 20ºC. The treatments were divided as follows: T1: clubroots frozen for 389 days (arugula); T2: clubroots frozen for 242 days (broccoli); T3: clubroots frozen for 21 days (Chinese cabbage), and T4: control (without inoculum). The pathogenicity tests were conducted under greenhouse conditions (25±2ºC). Each plant of the susceptible variety of Chinese cabbage (Pak choi) was inoculated with 2mL of a spore suspension of each treatment at a concentration of 10(7) spores.mL-1. Each treatment consisted of six replicates distributed in random blocks. The roots of plants were washed and evaluated five weeks after inoculation. There were significant differences between treatments. The frozen materials preserved their infective traits over a period of 21 to 242 days, demonstrating that the freezing method could be an option to preserve the resistance structures of this pathogen.
Descrição
Palavras-chave
Hérnia das crucíferas, patógeno de solo, patogenicidade, Clubroot, soilborne pathogen, pathogenicity
Como citar
Summa Phytopathologica. Grupo Paulista de Fitopatologia, v. 35, n. 1, p. 57-59, 2009.