Molecular Plant-Microbe Interactions (2005) 18, 1306-1317

Adriana Castañeda, Joseph D. Reddy, Basma El-Yacoubi and Dean W. Gabriel (2005)
Mutagenesis of all eight avr gnes in Xanthomonas campestris pv. campestris had no detected effect on pathogenicity, but one avr gene affected race specificity
Molecular Plant-Microbe Interactions 18 (12), 1306-1317
Abstract: Suppression subtractive hybridization (SSH) was used to identify genes present in the systemic crucifer black rot pathogen Xanthomonas campestris pv. campestris 528^T but missing from the nonsystemic crucifer leaf spot pathogen, X. campestris pv. armoraciae 417. Among the DNA fragments unique to 528 ^T was Xcc2109, one of eight putative avr genes identified in the published 528^T genome (NC_003902). Individual and sequential deletion, insertion mutations, or both of all eight 528^T avr gene loci were made, but no change in pathogenicity was observed with any combination of avr mutations, including a strain with all eight avr genes deleted. However, insertion or deletion mutants affecting the Xcc2109 locus lost avirulence (i.e., became virulent) on Florida Mustard, an X. campestris pv. campestris race-determining, differential host. The Xcc2109 open reading frame as annotated was cloned and found to be nonfunctional. A longer gene, encompassing Xcc2109 and here designated avrXccFM, was cloned and found to complement the Xcc2109 mutants and to confer avirulence to two additional wild-type X. campestris pv. campestris strains, thereby changing their races. Resistance in Florida Mustard to 528^T strains carrying avrXccFM occurred without a typical hypersensitive response (HR) on leaves, although a vascular HR was observed in seedlings.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Dean W. Gabriel

Research topic(s) for pests/diseases/weeds:
molecular biology - genes
resistance/tolerance/defence of host

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Xanthomonas campestris pv. campestris
	Xanthomonas campestris