Xanthomonas fuscans subsp. fuscans causing wilt symptoms in bean plants (Phaseolus vulgaris) in Brazil

Abstract

Common and fuscous blights of bean are diseases widely distributed in the world. The most commonly observed symptoms are spots on leaves, stems, pods and seeds. In December 2009, bean plants cv. Uirapuru showing symptoms of wilt similar to those induced by Curtobacterium flaccumfaciens pv. flaccumfaciens were observed in a commercial crop located in the county of Itararé, State of São Paulo, Brazil. The plants were at the last cycle stage with mature pods and these symptoms were noted in the majority of the growing area. Optical microscopic observations of discolored vascular tissue from diseased stems revealed the presence of bacterial masses oozed from infected tissue, indicating that the disease was caused by bacterial pathogen. Isolations on nutrient agar showed circular, convex, yellow colonies with smooth edges. The causal bacterium was Gramnegative and produced a dark brown pigment in culture medium. Biochemical, cultural and physiological tests confirmed its identity as Xanthomonas fuscans subsp. fuscans(syn. Xanthomonas campestris pv. phaseoli“var. fuscans"). The pathogenicity of the isolates was confirmed by artificial inoculations. Systemic infection has been reported in the literature but these kinds of symptoms are not currently observed in Brazilian fields. Bacterial strains were deposited on the Phytobacteria Culture Collection of Instituto Biológico (IBSBF - www.biologico.sp.gov.br/bacterias/php) under accession numbers 2813 and 3028.

Interaction between bacterial biocontrol-agents and strains of Xanthomonas axonopodis pv. phaseoli effects on biocontrol efficacy of common blight in beans

“…In Brazil, the disease commonly occurs in the states of Rio Grande do Sul, Rio de Janeiro, São Paulo, Minas Gerais, Paraná, Santa Catarina and in the central-west region. The disease is very damaging in rainy season crop (Almeida et al, 2015;Fourie, 2002) and losses of up to 50% have been reported (Vieira and Souza, 2000).…”

Bacterial endophytes: An agroecological alternative in the growth promotion and plant health management of cabbage leaf (Brassica oleracea var. acephala)

“…Lately, the genus has been responsible for countless losses in agricultural production worldwide (Quezado-Duval & Lopes, 2010), due to diseases such as leaf spots (Marcolin et al, 2015), necrotic stem lesions , leaves and fruits (Aiello et al, 2013), withered (Almeida et al, 2014), cancers (Moraes et al, 2011), among other symptoms, infecting a range of approximately 400 plant species, such as rice (Oryza sativa), bean (Phaseolus vulgaris), grape (Vitis vinifera), mango (Mangifera indica), passionfruit (Passiflora edulis), cassava (Manihot esculenta), cotton (Gossypium hirsutum), tomato (Solanum lycopersicum), potato (Solanum tuberosum), wheat (Triticum aestivum), neem (Azadirachta indica), citrus and crucifers (Leyns et al, 1984).…”

Genome‐wide association study (GWAS) of Phaseolus vulgaris resistance to Xanthomonas citri pv. fuscans

“…Among the factors that cause significant loss in the production of common bean is common bacterial blight (CBB). In Brazil, the disease is present in all common bean‐producing areas, causing most losses during the summer (Almeida et al, 2015; Torres et al, 2005). Disease symptoms initially appear as small water‐soaked lesions on the leaves, which grow to become necrotic lesions surrounded by chlorotic haloes.…”

“…phaseoli (Xpp). To date, no studies have determined which pathogen (Xcf or Xpp) is prevalent in Brazil, but it is known that both are present in most producing areas (Almeida et al, 2015; Torres et al, 2005).…”