Simultaneous detection and identification of the Xanthomonas species complex associated with tomato bacterial spot using species-specific primers and multiplex PCR

Authors

  • E.R. Araújo,

    1. Departamento de Fitopatologia, Instituto de Biologia, Universidade de Brasília, Brasília, DF, Brazil
    2. Laboratório de Fitopatologia, Embrapa Hortaliças, Brasília, DF, Brazil
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  • J.R. Costa,

    1. Laboratório de Fitopatologia, Embrapa Hortaliças, Brasília, DF, Brazil
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  • M.A.S.V. Ferreira,

    1. Departamento de Fitopatologia, Instituto de Biologia, Universidade de Brasília, Brasília, DF, Brazil
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  • A.M. Quezado-Duval

    Corresponding author
    1. Laboratório de Fitopatologia, Embrapa Hortaliças, Brasília, DF, Brazil
    • Departamento de Fitopatologia, Instituto de Biologia, Universidade de Brasília, Brasília, DF, Brazil
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Correspondence

Alice Maria Quezado-Duval, Laboratório de Fitopatologia, Embrapa Hortaliças, Rodovia Brasília/Anápolis BR 060 Km 09, Caixa Postal 218, CEP 70359-970, Brasília, DF, Brazil. E-mail: alice@cnph.embrapa.br

Abstract

Aims

To establish protocols for the simultaneous detection and identification of Xanthomonas species causing tomato bacterial spot.

Methods and Results

We verified the specificity and sensitivity of the previously reported sets of primers designed for strains of the four species of Brazilian tomato bacterial spot xanthomonads, consisting of 30 of Xanthomonas euvesicatoria, 30 of X. vesicatoria, 50 of X. perforans and 50 of X. gardneri. Furthermore, we tested a multiplex PCR protocol for the purpose of concurrent species identification. The possibility of direct detection of the pathogens in diseased leaf samples was also verified. The primers were highly specific, amplifying only target DNA. The sensitivity of the primers in conventional PCR was 50 pg μl−1 for purified DNA and ranged from 5 × 102 to 5 × 104 CFU ml−1 when bacterial suspensions were analysed. The multiplex PCR was suitable for the detection of all four species and showed similar sensitivity to conventional PCR when tested on purified DNA. When using bacterial suspensions, its sensitivity was similar to conventional PCR only when a biological amplification step (Bio-PCR) was included. Both methods were able to detect the pathogens in symptomatic tomato leaves.

Conclusions

Brazilian Xanthomonas strains causing tomato bacterial spot can be differentiated and identified at species level by a PCR-based method and by a multiplex PCR.

Significance and Impact of the Study

This protocol may be a feasible alternative tool for the identification and detection of these pathogens in plant material and may be used for routine diagnostic purposes in plant pathology laboratories.

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