Detecção e caracterização de Xylella fastidiosa em pomares de citros no estado do Amazonas e em São Paulo

Abstract

The Chlorosis Variegad of Citrus (CVC) popularly known as small yealow is a disease that is attacking the Brazilian orchards since 1987, with the causal agent the bacterium Xylella fastidiosa that colonizes the xilematic vessels mainly of sweet oranges (Citrus sinensis). In the states of São Paulo and Minas Gerais the disease has great impact especially in the north, northeastern state of Sao Paulo and Minas Gerais triangle, regions of warm climate where the bacteria presents major conditions for growth in xilematic vessels. There were isolated strains of X. fastidiosa of thirteen municipalities between Sao Paulo and Minas Gerais. The strains of X. fastidiosa in seedlings were inoculated in a greenhouse where there are differences in symptoms of plants and bacterial virulence. Among those inoculated strains of the municipalities Neves Paulista, Matão, Jeriquara and had greater frequency of symptoms, since the municipality Capela do Alto, southern state of São Paulo had the lowest frequency of symptoms. The CVC has been detected in several Brazilian states, but no reports of the occurrence of CVC had been done to the state of Amazonas, where the cultivation of citrus is being commercially exploited by at least three decades. An evaluation sample was held in Manaus, President Figueiredo, Itacoatiara, Balbina and Rio Preto da Eva, in the period August to December 2003, March to December 2004 and 2005 and January to March 2006. Were observed symptoms of CVC in sheets, as chlorotic spots arranged in front of leaves and straw color injuries in the back. Collected up 10 leafs of each plant for the isolation of the bacterium, extracting DNA and PCR specific for the identification and confirmation of the occurrence of the pathogen. According to the results presented were unable to detect the occurrence of CVC of citrus orchards in the state of Amazonas.