title: A duplex PCR assay for the detection of Ralstonia solanacearum phylotype II strains in Musa spp.
abstract: Banana wilt outbreaks that are attributable to Moko disease-causing strains of the pathogen Ralstonia solanacearum (Rs) remain a social and economic burden for both multinational corporations and subsistence farmers. All known Moko strains belong to the phylotype II lineage, which has been previously recognized for its broad genetic basis. Moko strains are paraphyletic and are distributed among seven related but distinct phylogenetic clusters (sequevars) that are potentially major threats to Musaceae, Solanaceae, and ornamental crops in many countries. Although clustered within the Moko IIB-4 sequevar, strains of the epidemiologically variant IIB-4NPB do not cause wilt on Cavendish or plantain bananas; instead, they establish a latent infection in the vascular tissues of plantains and demonstrate an expanded host range and high aggressiveness toward Solanaceae and Cucurbitaceae. Although most molecular diagnostic methods focus on strains that wilt Solanaceae (particularly potato), no relevant protocol has been described that universally detects strains of the Musaceae-infecting Rs phylotype II. Thus, a duplex PCR assay targeting Moko and IIB-4NPB variant strains was developed, and its performance was assessed using an extensive collection of 111 strains representing the known diversity of Rs Moko-related strains and IIB-4NPB variant strains along with certain related strains and families. The proposed diagnostic protocol demonstrated both high accuracy (inclusivity and exclusivity) and high repeatability, detected targets on either pure culture or spiked plant extracts. Although they did not belong to the Moko clusters described at the time of the study, recently discovered banana-infecting strains from Brazil were also detected. According to our comprehensive evaluation, this duplex PCR assay appears suitable for both research and diagnostic laboratories and provides reliable detection of phylotype II Rs strains that infect Musaceae.
authors: French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Plant Health Laboratory (LSV), Tropical Pests and Diseases Unit, Saint Pierre 97410, Reunion, France.
authors: Gilles
authors: G
authors: Cellier
authors: French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Plant Health Laboratory (LSV), Tropical Pests and Diseases Unit, Saint Pierre 97410, Reunion, France.
authors: Aurélie
authors: A
authors: Moreau
authors: French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Plant Health Laboratory (LSV), Tropical Pests and Diseases Unit, Saint Pierre 97410, Reunion, France.
authors: Aude
authors: A
authors: Chabirand
authors: French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Plant Health Laboratory (LSV), Tropical Pests and Diseases Unit, Saint Pierre 97410, Reunion, France.
authors: Bruno
authors: B
authors: Hostachy
authors: French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Plant Health Laboratory (LSV), Tropical Pests and Diseases Unit, Saint Pierre 97410, Reunion, France; Centre de coopération internationale en recherche agronomique pour le développement (CIRAD), Unité Mixte de Recherche (UMR) Peuplements Végétaux et Bioagresseurs en Milieu Tropical (PVBMT), Saint Pierre 97410, Reunion, France.
authors: Florent
authors: F
authors: Ailloud
authors: Institut national de la Recherche Agronomique (INRA), Department of Plant Health and Environment (SPE)-Centre de coopération internationale en recherche agronomique pour le développement (CIRAD), Unité Mixte de Recherche (UMR) Peuplements Végétaux et Bioagresseurs en Milieu Tropical (PVBMT), Saint Pierre 97410, Reunion, France.
authors: Philippe
authors: P
authors: Prior
mesh_terms: D044822:Biodiversity; D001938:Brazil; D028521:Musa / Q000382:microbiology* / Q000821:virology; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology; D016133:Polymerase Chain Reaction; D043368:Ralstonia solanacearum / Q000145:classification* / Q000235:genetics*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity