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.
Bottom Line: In a previous study, we found that UMAF6639 was able to induce systemic resistance (ISR) in melon and provide additional protection against powdery mildew.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.These results reinforce the biotechnological potential of UMAF6639 as a biological control agent.
Affiliation: Instituto de Hortofruticultura Subtropical y Mediterránea 'La Mayora'-IHSM-UMA-CSIC, Departamento de Microbiología, Universidad de Málaga, Bulevar Louis Pasteur 31-Campus Universitario de Teatinos, 29071 Málaga, Spain.Show MeSH
Related in: MedlinePlus
Mentions: To determine the signalling pathways elicited by B. subtilis UMAF6639 and the other two ISR-inducing strains, expression of LOX2 (lipoxygenase 2, a JA-responsive marker gene), PR1 (an SA-responsive marker gene) and PR9 (peroxidase, a gene related to the hypersensitive response and cell wall reinforcement and inducible by SA and JA) (Durrant and Dong, 2004; van Loon et al., 2006; Pieterse et al., 2009) was analysed using quantitative RT-PCR (Fig. 2). In these assays, leaf samples of bacterized and non-bacterized melon plants were collected before (time 0), and 24 or 48 h after inoculation with P. fusca. Before inoculation with the pathogen, bacterized plants displayed a slight but not significant increase in the expression of LOX2 compared with non-bacterized control plants (Fig. 2, upper panel). After inoculation, the expression of this gene was increased only in plants treated with Bacillus species. A maximum twofold increase in signal was reached 24 h and 48 h after inoculation of the pathogen in the case of B. cereus UMAF8564 and B. subtilis UMAF6639 respectively. The expression of the other two PR genes (PR1 and PR9) was triggered 48 h after inoculation of P. fusca and also in Bacillus-treated plants (Fig. 2, middle and bottom panels respectively). In these cases, the highest expression level (40-fold increase) was elicited after treatment with B. cereus UMAF8564. The increased expression of PR1, which is a typical SA-responsive marker gene, suggested that the ISR response induced by the Bacillus strains was dependent on SA signalling. However, the limited increase of expression observed for LOX2 did not convincingly reflect the dependence on JA signalling of such a response.
Affiliation: Instituto de Hortofruticultura Subtropical y Mediterránea 'La Mayora'-IHSM-UMA-CSIC, Departamento de Microbiología, Universidad de Málaga, Bulevar Louis Pasteur 31-Campus Universitario de Teatinos, 29071 Málaga, Spain.