Cloning of genes involved in pathogenicity of Xanthomonas campestris pv. campestris using the broad host range cosmid pLAFR1

Abstract

A genomic library was prepared in Escherichia coli from DNA of wild‐type Xanthomonas campestris pv. campestris (aetiological agent of crucifer black rot), partially digested with endonuclease EcoRI, using the mobilisable broad host range cosmid vector pLAFR1. Recombinant plasmids contained inserts ranging in size from 19.1 to 32.3 kb (mean 26.6). Certain of the clones complemented E. coli auxotrophic markers. Using the narrow host range plasmid pRK2013 as a helper the pooled recombinant plasmids were transferred conjugally to X. c. campestris mutants, and clones were identified which restored yellow pigmentation to white mutants, prototrophy to amino acid auxotrophs and pathogenicity towards turnip plants to two non‐pathogenic mutants. The lesion in one mutant (8288, complemented by the plasmid pIJ3000) is unknown. However mutant 8237 is defective in production of extracellular protease and polygalacturonate lyase and restoration of pathogenicity by complementation with the plasmid pIJ3020 concomitantly restored both enzyme levels to wild‐type values.

High-molecular-mass multicatalytic proteinase complexes produced by the nitrogen-fixing actinomycete Frankia strain BR

“…Results indicating that pectolytic and proteolytic activities are needed for phytopathogenicity of Xanthomonas campestris pv. campestris, (8) (21).…”

JIPs and RIPs: the regulation of plant gene expression by jasmonates in response to environmental cues and pathogens.

“…Nevertheless, one might speculate that pathogens may be able to elicit the immediate marking of the plant ribosome. Consistent with this idea, pathogen-encoded enzymes have been shown to be involved in the signal transduction chain by which plants activate local and systemic resistance responses against pathogens (Daniels et al, 1984;Dow et al, 1987). It remains to be investigated how plant ribosomes are marked for cleavage by JIP60 and whether pathogens may promote this effect.…”

Expression of the Xanthomonas campestris pv. vesicatoria hrp gene cluster, which determines pathogenicity and hypersensitivity on pepper and tomato, is plant inducible

“…In the last few years, a number of bacterial genes that determine the outcome of the interaction between the bacterium and the plant have been identified and isolated. Most notable are two classes of genes required for basic compatibility: disease-specific (dsp) genes, which are associated with disease development in host plants but not with the induction of a hypersensitive response (HR) in nonhost plants (7,27); and hrp genes, which are required for both the pathogenic interaction with host plants and the induction of the HR in resistant host and nonhost plants. hrp genes have been cloned from a number of different species of gram-negative phytopathogenic bacteria, e.g., Erwinia amylovora, Pseudomonas solanacearum, and pathovars of Pseudomonas syringae and ofXanthomonas campestris (for a review, see reference 35).…”