Detection of a Bacterium Associated with a Leaf Spot Disease of Maize in Brazil

Abstract

A leaf spot disease of maize occurring in Brazil in the 1980s was described as being caused by the ascomycete Phaeosphaeria maydis (P. Henn) Rane. Payak and Renfro (imperfect form Phyllosticta sp.). Disease symptoms were dark‐green water‐soaked spots that later became necrotic lesions. There are no reports at present in the literature of re‐infection by the fungus under controlled conditions, casting doubt on the true identity of the pathogen. In this study, cytological analyses of lesions at the initial stages did not detect the presence of fungal structures. Bacterial colonies with yellow pigmentation were isolated from the lesions, which reacted positively in hypersensitivity tests in tobacco plants. Maize plants were inoculated with the isolated bacteria. After 72 h incubation in a dew chamber, plants were transferred to a greenhouse, where they remained until evaluation. Typical symptoms of the disease were observed 5–7 days after inoculation of plants, only on treatments inoculated with the bacteria. The bacterium was re‐isolated, which suggests its involvement in the initial phases of disease. The bacterium was identified as Pantoea ananas (synonym Erwinia ananas).

First report of pathogenicity ofPantoea ananatisin sorghum (Sorghum bicolor) in Brazil

“…In Mexico, maize is an important cereal for human nutrition and P. ananatis has been detected causing leaf spots on corn (Pérez-y-Terrón et al 2009). This disease has also been reported in two other South American maize-producing countries: Argentina (Alippi and López 2010) and Brazil (Paccola-Meirelles et al 2001).…”

“…Artificial inoculations have shown this organism to be pathogenic to sugarcane, oats, cotton and sorghum (Sorghum bicolor) (Azad et al 2000;Coutinho and Venter 2009). On maize P. ananatis was identified as the causal agent of white spot (Paccola-Meirelles et al 2001;Bomfeti et al 2008) where it caused more than 60% yield losses on susceptible genotypes (Pinto 1999). Sawazaki et al (1997) has also shown a correlation between the incidence of white spot on maize and a reduction in corn kernel weight.…”

A FAFLP system for the improved identification of plant-pathogenic and plant-associated species of the genus Pantoea

“…indologenes is associated with sudangrass [3] and is thought to cause leaf spot on foxtail millet and pearl millet and rot of pineapple. Pantoea agglomerans is best known for causing crown and root gall of Gypsophila paniculata [6] and Pantoea ananatis causes a range of diseases on a wide variety of agricultural crops, the most recent including rice [8], Eucalyptus [9], maize [14] and sudangrass [3]. Pantoea citrea is associated with citrus fruit and causes pink disease of pineapple [11] and [15].…”

Elaboração e validação da escala diagramática para avaliação da mancha branca do milho

“…A doença provoca formação de manchas brancas com formatos irregulares, que sob condições favoráveis podem levar a senescência das folhas, reduzindo o ciclo e a produtividade, sendo a quantidade e o tamanho das lesões variáveis entre as variedades (PACCOLA-MEIRELLES et al, 2001). …”