Abstract
ABSTRACT In 2016, several reports emerged of fresh-market staked tomato plants with severe symptoms of pith necrosis and premature death in commercial cultivation areas in the states of Paraná and Minas Gerais, Brazil, which are similar to those caused by Pseudomonas corrugata. Four bacterial strains were isolated from infected tissue samples and characterized as Gram-negative, aerobic, and fluorescent on King’s B Medium. LOPAT tests were performed and the isolate UFU H120 was classified into group Vb (+ + − + −) and the isolates UFU H3, UFU H6, and UFU H21 into group Va (− + − + −). The pathogenicity of the isolates was confirmed by artificial inoculation on tomato plants of Santa Cruz type, cv. Kada Gigante, and Koch’s postulates were accomplished successfully. The isolates sequences of their 16S rRNA gene region were compared with those deposited in GenBank, the isolate UFU H120 aligning with Pseudomonas fluorescens (99,45% similarity) and the isolates UFU H3, UFU H6, and UFU H21 with Pseudomonas putida (99.2, 99.53 and 99.64% similarity, respectively). Notably, P. fluorescens and P. putida are most known as saprophytic bacteria normally present in the soil, although both of these species have already been reported to infect tomato plants in Italy. However, so far, there have not been any reports of such bacteria being phytopathogenic on tomato or any crop in Brazil. Thus, to our knowledge, this is the first report of pith necrosis of such occurrence in Brazil.
Highlights
Em 2016 em tomateiro tutorado para consumo in natura, foram observadas plantas com sintomas graves de necrose da medula e morte prematura da planta, em áreas de cultivo comercial nos estados do Paraná e Minas Gerais, Brazil, similares aos causados por Pseudomonas corrugata
Obtained isolates In 2016, in the states of Paraná and Minas Gerais, Brazil, in open field commercial cultivation areas staked tomatos plants were observed with severe symptoms of pith necrosis and premature death, similar to those described for Pseudomonas corrugata
Bacterial isolation was performed from four infected tomato plant tissues with severe necrotic symptoms on the pith region of stem basis (Figures 1A, 1B, 1C) from Araguari-MG (UFU H3, University of Uberlândia (UFU) H6); Silvestre-PR (UFU H21); and Uberlândia-MG (UFU H120)
Summary
Em 2016 em tomateiro tutorado para consumo in natura, foram observadas plantas com sintomas graves de necrose da medula e morte prematura da planta, em áreas de cultivo comercial nos estados do Paraná e Minas Gerais, Brazil, similares aos causados por Pseudomonas corrugata. A panel of biochemical (LOPAT) is recommended for the genus Pseudomonas (Lelliott & Stead, 1987; Schaad et al, 2001) These tests are not always sufficient for a precise identification of the species or pathovar associated to a given plant disease. This is because of the great biochemical and genetic diversity of the species; more than 100 species described in genus, as well as the possible emergence of new species or pathovars that have not been previously described for the crop or repositioning of species in the taxon (Garrido-Sanz et al, 2016)
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