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Updated: May 28, 2026
Plant-Microbe Interaction: Transcriptional Response of Bacillus Mycoides to Potato Root Exudates
Published on: July 2, 2018
Bacillus amyloliquefaciens-induced resistance against the olive knot disease: An integrated transcriptomic and
Ana E Cunha1,2, José Alberto Pereira1, Pedro Casquero2
1CIMO, LA SusTEC, Instituto Politécnico de Bragança, Bragança, Portugal.
Background:
Bacillus amyloliquefaciens is a broad-spectrum biocontrol agent, but its molecular mode of protection in plants remains poorly understood. This study assessed its effect against olive knot disease, caused by Pseudomonas savastanoi pv. savastanoi (Pss), and elucidated the underlying transcriptional and metabolic responses. Olive plantlets received the following treatments: inoculation with B. amyloliquefaciens or Pss alone, pre-inoculation with B. amyloliquefaciens followed 14 days later by Pss, or buffer, and were sampled at 0, 24, and 48 h post inoculation (hpi) for transcriptomic [RNA sequencing (RNA-seq)] and untargeted metabolomic analyses.
Results:
Pre-inoculation with B. amyloliquefaciens significantly reduced disease incidence and severity. RNA-seq revealed an immediate response following inoculation (0 hpi) with the upregulation of defense- and cytoskeleton-related genes, followed by a second phase (48 hpi) involving genes related to secondary metabolism, redox balance, nutrient assimilation, and signaling, consistent with sustained resistance. Plants treated with pathogen alone showed limited transcriptional activation and repression of stress- and metabolism-related genes. Metabolomic analysis showed biphasic reprogramming in primed plants, with early (0 hpi) accumulation of primary metabolites for energy and flavonoids for potentially antimicrobial defense and structural fortification, followed by later (48 hpi) increases in hormone-related compounds and secondary metabolites, including flavonoids and alkaloids. Pathogen-only plants displayed weaker and transient metabolic changes.
Conclusion:
B. amyloliquefaciens can enhance olive resistance via host-mediated priming, and extensive transcriptional and metabolic reprogramming, which may contribute to a rapid and sustained defense against Pss. Specific flavonoids and alkaloids identified in this study may serve as biomarkers of resistance and targets to improve olive knot disease management. © 2026 Society of Chemical Industry.
