Epidemiological evidence for the emergence of a new pathogenic variant of Ralstonia solanacearum in Martinique (French West Indies)

Abstract

The emergence of a new genotype and pathogenic variant of Ralstonia solanacearum in Martinique is described. Bacterial wilt of solanaceous crops caused by phylotype-I and -II strains ('historical strains'), was reported in Martinique in the 1960s. From 1999, Anthurium and cucurbit production was strongly affected by strains described as a new pathogenic variant genotyped phylotype IIB/sequevar4NPB (phIIB/4NPB). The following questions concerning these strains were investigated: (i) were they introduced or endemic, (ii) was their distribution widespread in Martinique, and (iii) which factors could explain this emergence? This study examined 221 isolates collected from 1989 to 2003 after several surveys. The main survey (2002-03) included 115 vegetable and ornamental crop farms. From 1999 to 2001, these phIIB/4NPB strains were initially described as the 'Anthurium-cucurbit' strain. In 2003, they made up one-third of the isolates recovered from solanaceous hosts, particularly tomato. This pathogenic variant of R. solanacearum was consistently recovered from wild species and several weeds throughout Martinique, suggesting that these strains were well established in Martinique. Data reported are consistent with the emergence of a new population of R. solanacearum in Martinique, which has spread rapidly across the entire island and may overtake the previously established population, particularly on tomatoes. Evidence is presented which suggests that the emergence of these new strains is more frequent on vegetable crops when cucurbitaceous and musaceous plants are grown in succession.

Phylogeny and Population Structure of Brown Rot- and Moko Disease-Causing Strains of Ralstonia solanacearum Phylotype II

“…Emerging strains from sequevar 4NPB are not pathogenic to banana and are highly aggressive on Solanaceae, whereas all Moko IIB-4 strains are highly pathogenic to banana, and some retained pathogenicity to Solanaceae and could overcome genetic resistance resources (5). These data are consistent with the assumption that strains IIB-4NPB emerged from the IIB-4 lineage as a new ecotype (43). This hypothesis suggests that a loss of particular pathogenicity traits could trigger an emergence of highly host adapted strains.…”

Wide genetic diversity of Ralstonia solanacearum strains affecting tomato in Trinidad, West Indies

“…, 2007). This group is highly pathogenic in solanaceous crops, and is capable of spreading rapidly throughout a territory, as was observed in Martinique (Wicker et al. , 2009b).…”

“…This study provides the first comprehensive information on populations of R. solanacearum affecting tomatoes in a southern Caribbean country, showing that great variability exists between neighbouring islands (Wicker et al. , 2009b).…”

Phylotype and sequevar variability of Ralstonia solanacearum in Brazil, an ancient centre of diversity of the pathogen

“…The diversity of R . solanacearum in South America and in the Caribbean has been studied in Venezuela (García et al ., ), Colombia (Cardozo et al ., ), Uruguay (Siri et al ., ), French Guiana (Deberdt et al ., ), Brazil (Pinheiro et al ., ; Santana et al ., ; Garcia et al ., ; Albuquerque et al ., ), Martinique (Wicker et al ., ) and Trinidad and Tobago (Ramsubhag et al ., ). In Brazil, the most recent study (Albuquerque et al ., ) was conducted using banana and potato isolates obtained from small areas.…”