[Detection system for Xanthomonas axonopodis pv. citri using rolling circle amplification]

Area of Science:

• Molecular Biology
• Plant Pathology
• Genetics

Context:

• Xanthomonas axonopodis pv. citri (Xac) causes citrus canker, a significant threat to citrus production worldwide.
• Accurate and sensitive detection of Xac is crucial for effective disease management and preventing its spread.
• Current diagnostic methods may lack the required specificity or sensitivity for early-stage detection.

Purpose:

• To develop and optimize a novel detection system for Xac using padlock probes and rolling circle amplification (RCA).
• To evaluate the specificity and sensitivity of the developed RCA system compared to conventional polymerase chain reaction (PCR).
• To assess the applicability of the RCA system for detecting Xac in field-collected plant samples.

Summary:

• A padlock probe targeting a unique gene in Xac was designed, coupled with universal primers for amplification.
• The established rolling circle amplification (RCA) system demonstrated high specificity, distinguishing Xac from other bacteria and plant pathogens.
• The RCA method achieved a sensitivity of 20 cfu/µL for Xac cells and 10^2 copies/µL for DNA fragments, comparable to or slightly exceeding conventional PCR.

Impact:

• The developed RCA detection system offers a specific and sensitive tool for identifying Xac, crucial for citrus disease management.
• Its ability to detect pathogens before symptoms appear supports pre-symptomatic diagnosis in plant quarantine and disease surveillance.
• The use of universal linking sequences allows for simultaneous detection of diverse plant pathogens, enhancing diagnostic capabilities.