A multifunctional citrus-derived antimicrobial peptide controls vascular bacterial pathogens.

Area of Science:

• Plant Pathology
• Molecular Biology
• Agricultural Science

Background:

• Phloem-restricted bacteria, such as Candidatus Liberibacter species, cause significant crop diseases like citrus Huanglongbing (HLB) and potato zebra chip disease (ZCD).
• Current control methods for ZCD, caused by Candidatus Liberibacter solanacearum (CLso) and transmitted by potato psyllids, are limited and raise environmental concerns.
• A previously identified stable antimicrobial peptide (SAMP) from Australian finger lime inhibits CLas, the agent of citrus HLB.

Purpose of the Study:

• To evaluate the efficacy of SAMP in controlling CLso in solanaceous crops (potato, tomato) and Xanthomonas campestris pv. Campestris (Xcc) in Arabidopsis thaliana.
• To assess the potential of SAMP for bioengineering disease-resistant plants against vascular bacterial pathogens.

Main Methods:

• Topical application of SAMP on potato and tomato plants.
• Greenhouse trials to assess resistance to CLso.
• Transgenic expression of SAMP in potato and Arabidopsis, followed by pathogen challenge.
• Evaluation of bacterial titers and insect vector suppression.

Main Results:

• Topical SAMP application enhanced resistance to CLso in potato and tomato plants.
• Transgenic potato and Arabidopsis plants expressing SAMP showed reduced bacterial titers without growth defects.
• SAMP effectively suppressed CLso within the insect vector.
• SAMP demonstrated broad-spectrum activity against both CLso and Xcc.

Conclusions:

• SAMP exhibits broad-spectrum efficacy against vascular bacterial pathogens, including CLso and Xcc.
• SAMP has potential as a sustainable, cross-crop tool for bioengineering disease-resistant plants.
• This peptide can enhance plant immunity beyond citrus species, offering a novel disease management strategy.