The antagonistic strain Bacillus subtilis UMAF6639 also confers protection to melon plants against cucurbit powdery mildew by activation of jasmonate- and salicylic acid-dependent defence responses

Authors

  • Laura García-Gutiérrez,

    1. Instituto de Hortofruticultura Subtropical y Mediterránea ‘La Mayora’ (IHSM-UMA-CSIC), Departamento de Microbiología, Universidad de Málaga, Málaga, Spain
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  • Houda Zeriouh,

    1. Instituto de Hortofruticultura Subtropical y Mediterránea ‘La Mayora’ (IHSM-UMA-CSIC), Departamento de Microbiología, Universidad de Málaga, Málaga, Spain
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  • Diego Romero,

    1. Instituto de Hortofruticultura Subtropical y Mediterránea ‘La Mayora’ (IHSM-UMA-CSIC), Departamento de Microbiología, Universidad de Málaga, Málaga, Spain
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  • Jaime Cubero,

    1. Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Madrid, Spain
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  • Antonio de Vicente,

    1. Instituto de Hortofruticultura Subtropical y Mediterránea ‘La Mayora’ (IHSM-UMA-CSIC), Departamento de Microbiología, Universidad de Málaga, Málaga, Spain
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  • Alejandro Pérez-García

    Corresponding author
    • Instituto de Hortofruticultura Subtropical y Mediterránea ‘La Mayora’ (IHSM-UMA-CSIC), Departamento de Microbiología, Universidad de Málaga, Málaga, Spain
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  • Funding Information This study was supported by a grant from the Plan Nacional de I+D+I of the former Ministerio de Ciencia e Innovación, Spain (AGL2010-21848-C02-01), and co-financed by FEDER funds (European Union).

For correspondence. E-mail aperez@uma.es; Tel. (+34) 952131890; Fax (+34) 952136645.

Summary

Biological control of plant diseases has gained acceptance in recent years. Bacillus subtilis UMAF6639 is an antagonistic strain specifically selected for the efficient control of the cucurbit powdery mildew fungus Podosphaera fusca, which is a major threat to cucurbits worldwide. The antagonistic activity relies on the production of the antifungal compounds iturin and fengycin. In a previous study, we found that UMAF6639 was able to induce systemic resistance (ISR) in melon and provide additional protection against powdery mildew. In the present work, we further investigated in detail this second mechanism of biocontrol by UMAF6639. First, we examined the signalling pathways elicited by UMAF6639 in melon plants, as well as the defence mechanisms activated in response to P. fusca. Second, we analysed the role of the lipopeptides produced by UMAF6639 as potential determinants for ISR activation. Our results demonstrated that UMAF6639 confers protection against cucurbit powdery mildew by activation of jasmonate- and salicylic acid-dependent defence responses, which include the production of reactive oxygen species and cell wall reinforcement. We also showed that surfactin lipopeptide is a major determinant for stimulation of the immune response. These results reinforce the biotechnological potential of UMAF6639 as a biological control agent.

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