Invasive Species Compendium

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Abstract

Detection of Pantoea agglomerans in germplasm rice accessions (Oryza sativa) in Brazil.

Abstract

The cultivated area devoted to rice crops (Oryza sativa) in Brazil has expanded in recent years, along with improvements in yield. This has prompted the continuous exchange of material from active germplasm banks between government breeding programmes. When placed in a greenhouse for multiplication purposes, rice accessions resulting from exchanges between USDA-ARS showed little or no germination. The accessions were sent to the tissue culture laboratory of the Embrapa National Rice and Bean Research Centre to recover embryos by aseptically removing the seed coat of 10 seeds from each accession. Bacterial colony growth concomitant to germination inhibition was observed in some accessions, from which four bacterial isolates were obtained. Hypersensitive response in tobacco plants and pathogenicity by inoculation in 'Caloro' rice plants were positive for two bacterial isolates (Bac 2821 and Bac 2926). Both isolates produced symptoms of light brown leaf spots, progressing to leaf browning and drying. Based on biochemical, physiological and molecular (nucleotide sequence analysis) studies, the isolates were identified as P. agglomerans. This is thought to be the first report of P. agglomerans in germplasm of rice seeds in Brazil.