Naktuinbouw Laboratories has improved the dilution plating test for the detection of Xanthomonas 'bacterial spot' pathogens on tomato, pepper, and eggplant seeds. After dilution plating all suspect colonies are confirmed with a real-time PCR assay. For this assay, the markers have been improved in line with the seed extract PCR. This allows detection of the taxonomic groups Xanthomonas hortorum pv. gardneri, Xanthomonas vesicatoria and Xanthomonas euvesicatoria pv. euvesicatoria and Xanthomonas euvesicatoria pv. perforans (the latter two cannot be distinguished).
PCR is a technique for sensitive detection of specific species. The method involves collecting bacterial colonies from the dilution-plating plates and extracting their DNA. Pathogen-specific markers are then used to confirm the presence a specific bacteria. This makes it possible to confirm with more certainty whether the seed samples actually contain the live pathogen.
Bacteria
The species Xanthomonas euvesicatoria pv. euvesicatoria, X. euvesicatoria pv. perforans, X. hortorum pv. gardneri and X. vesicatoria (formerly known as the X. campestris pv. vesicatoria complex) result in necrotic spots on all above-ground plant parts and result in significant crop losses, primarily in tomato and pepper.
Source: Nak Tuinbouw