Effect of lactic acid bacteria on the control of Fusarium oxysporum and Ralstonia solanacearum on singly infected and co-infected tomato plants.

AIM

To evaluate the effect of lactic acid bacteria (LAB) on the control of Fol59 and Rs on singly infected and co-infected tomato plants and to address molecular pathways that may be involved in this interaction.

METHODS AND RESULTS

To assess the development of the disease, individual infection and coinfection were stimulated in plants under controlled conditions, at two concentrations of Rs and Fol59 applied at two different moments. Additionally, the antagonistic activity of LAB against Rs and Fol59 in vitro and its biocontrol efficacy in planta were evaluated. Preliminary results indicate that inoculation with 1 × 106 microconidia ml-1 of Fol59 and 1 × 108 cfu ml-1 of Rs may be a reliable synchronous coinfection method. Of the 68 LAB strains evaluated in vitro, AC13, AC40, and AC49 had an antagonistic effect on both pathogens, with AC40 showing the highest efficacy rate after submerging the seeds in suspension and sowing them in substrate. Finally, gene expression experiments confirmed the AC40 effect on the expression of PR-1a, ERF1, and LoxA genes.

CONCLUSION

The delayed appearance of symptoms and the reduced severity of the disease may be associated with the expression of PR-1a, ERF1, and LoxA genes related to salicylic acid, ethylene, and jasmonic acid pathways respectively.