Characterization of atypical Erwinia carotovora strains causing blackleg of potato in Brazil

Abstract

Aims: To determine the characteristics of bacteria associated with the blackleg disease of potato in Brazil and compare them with species and subspecies of pectolytic Erwinia. Methods and Results: Biochemical and physiological characteristics of 16 strains from blackleg-infected potatoes in State of Rio Grande do Sul, Brazil, were determined and differentiated them from all the E. carotovora subspecies and E. chrysanthemi. Pathogenicity and maceration ability of the Brazilian strains were greater than those of E. carotovora subsp. atroseptica, the causal agent of potato blackleg in temperate zones. Analyses of serological reaction and fatty acid composition confirmed that the Brazilian strains differed from E. carotovora subsp. atroseptica, but the sequence of 16S rDNA gene and the 16S-23S intergenic spacer (IGS) region confirmed the Brazilian strains as pectolytic Erwinia. Restriction analysis of the IGS region differentiated the Brazilian strains from the subspecies of E. carotovora and from E. chrysanthemi. A unique SexAI restriction site in the IGS region was used as the basis for a primer to specifically amplify DNA from the Brazilian potato blackleg bacterium in PCR. Conclusions: The bacterium that causes the blackleg disease of potato in Brazil differs from E. carotovora subsp. atroseptica, the blackleg pathogen in temperate zones. It also differs from other subspecies of E. carotovora and from E. chrysanthemi and warrants status as a new subspecies, which would be appropriately named E. carotovora subsp. brasiliensis. Significance and Impact of the Study: The blackleg disease of potato is caused by a different strain of pectolytic Erwinia in Brazil than in temperate potato-growing regions. The Brazilian strain is more virulent than E. carotovora subsp. atroseptica, the usual causal agent of potato blackleg.

Bacteria and Yeast Associated with Sugar Beet Root Rot at Harvest in the Intermountain West

“…The two P. betavasculorum strains, B20 and B22, were positive for utilization of Tween-80 and N-acetyl-D-glucosamine in the Biolog tests, distinguishing them from E. carotovora subsp. brasiliensis (10).…”

Erwinia chrysanthemi: pectolytic bacterium causing soft rot outbreaks of arracacha in Brazil

“…The predominance of Ech (89.8%) causing soft rot in arracacha roots in Brazil is a novel finding, since previous papers reporting the disease considered Ecc as the predominant one (Romeiro et al, 1988;Lopes & Quezado-Soares, 1997), although based on the identification of few isolates. Lately, Oliveira et al (2003) described Eca (55%) and Ecc (44%) as the predominant subspecies in potato fields in Southern Brazil, which was unexpected, and more recently, Duarte et al (2004) reported a new, atypical potato blackleg strain called E. carotovora subsp. brasiliensis.…”

“…Recently, atypical strains causing blackleg of potato in Southern Brazil were proposed as a new subspecies (E. carotovora subsp. brasiliensis) by Duarte et al (2004).…”

“…After 25 cycles, the results of PCR were separated by agarose gel (1%) electroforese for one hour. The PCR-IGS were performed at the following conditions: 94 o C/2 min, (94 o C/ 45 sec, 62 o C/45 sec, 72 o C/90 min) 25X, 72 o C/10 min, 4 o C/5 min (Duarte et al, 2004). Two representative isolates of Ech from arracacha roots were also submitted to the Biolog system, based on the utilization of 95 sources of carbon.…”

First report of blackleg and soft rot of potato caused by Pectobacterium carotovorum subsp. brasiliensis in New Zealand

“…Further characterisation of these aggressive isolates using PCR assays to distinguish Pcc from P. carotovorum subsp. brasiliensis (Pbr) was carried out using primers EXPCCF and EXPCCR (Kang et al, 2003) and Br1f and L1r (Duarte et al, 2004), respectively. From 18 isolates, occurring throughout the four major growing localities (Fig.…”