Abstract:
The present study developed a pathovar-specific PCR for the detection of Xanthomonas campestris pv. musacearum (Xcm),
the cause of banana xanthomonas wilt, by amplification of a 265-bp region of the gene encoding the general secretion
pathway protein D (GspD). A distinct DNA fragment of the expected size was amplified from genomic DNA from all of 12
Xcm isolates tested and no amplification of DNA was observed from other xanthomonads or plant-associated bacteria,
including the two closely related species Xanthomonas vasicola pv. holcicola and Xanthomonas axonopodis pv. vasculorum.
The Xcm-specific PCR was successfully multiplexed with internal control primers targeting 16S rDNA for application
on DNA from bacterial cultures and with primers targeting plant mitochondrial 26S rDNA for application on DNA
extracted from plant material. Diagnostic discrimination of healthy and infected plants was subsequently demonstrated in
tests on artificially inoculated screenhouse cultivars of banana and field bananas with and without symptoms sampled from
different parts of Uganda. This study therefore demonstrated a robust and specific Xcm diagnostic tool with the added
advantage of applying internal PCR controls for direct quality assessment of results.