Examination of the reported nucleotide sequences containing avirulence genes of Pseudomonas syringae pathovars suggested that avrA, avrB, avrC, avrPphC, avrRpm1, and avrPpiA1 are bordered by sequences similar to those of transposable elements of gram-negative bacteria. Repeat sequences and fragments of at least two different insertion sequence elements were identified at the ends of avrA and av...

Although more than 30 bacterial avirulence genes have been cloned and characterized, the function of the gene products in the elictitation of resistance is unknown in all cases but one. The product of avrD from Pseudomonas syringae pv. glycinea likely functions indirectly to elicit resistance in soybean, that is, evidence suggests the gene product is an enzyme involved in elicitor production. I...

For many years, plant pathology was divided into two schools of thought. It was clear that purified molecules or crude extracts from microbes or plants (referred to as general elicitors) could induce activation of general defense responses (Boller, 1995). Geneticists instead were studying plant resistance triggered by the recognition of a given pathogen Avirulence gene product by the correspond...

For many years, plant pathology was divided into two schools of thought. It was clear that purified molecules or crude extracts from microbes or plants (referred to as general elicitors) could induce activation of general defense responses (Boller, 1995). Geneticists instead were studying plant resistance triggered by the recognition of a given pathogen Avirulence gene product by the correspond...

Many plant pathogenic bacteria possess a conserved protein secretion system that is thought to transfer Avr (avirulence) proteins, with potential activities in both parasitism and defense elicitation, into plant cells. avr genes may be acquired horizontally by these bacteria, and avr gene compositions are highly variable. In the past year, heterologous expression experiments have revealed that ...

Three different cosmid clones were isolated from a genomic library of the tomato pathogen Pseudomonas syringae pv. tomato, which, when introduced into the soybean pathogen P. syringae pv. glycinea, caused a defensive hypersensitive response (HR) in certain soybean cultivars. Each clone was distinguished by the specific cultivars that reacted hypersensitively and by the intensity of the HR elici...

AvrXa7 is a member of the avrBs3 avirulence gene family, which encodes proteins targeted to plant cells by a type III secretion apparatus. AvrXa7, the product of avrXa7, is also a virulence factor in strain PXO86 of Xanthomonas oryzae pv. oryzae. Avirulence and virulence specificities are associated with the central repeat domain, which, in avrXa7, consists of 25.5 direct repeat units. Mutation...

A molecular genetic approach was used to identify and characterize plant genes that control bacterial disease resistance in Arabidopsis. A screen for mutants with altered resistance to the bacterial pathogen Pseudomonas syringae pv. tomato (Pst) expressing the avirulence gene avrRpt2 resulted in the isolation of four susceptible rps (resistance to P. syringae) mutants. The rps mutants lost resi...

ABSTRACT Sixty Ecuadorian isolates of Phytophthora infestans from potato and 60 isolates from tomato were compared for dilocus allozyme genotype, mitochondrial DNA haplotype, mating type, and specific virulence on 11 potato R-gene differential plants and four tomato cultivars, two of which contained different Ph genes. Restriction fragment length polymorphism (RFLP) fingerprints of subsamples o...

Brubaker, Robert R. (Fort Detrick, Frederick, Md.) and Michael J. Surgalla. Genotypic alterations associated with avirulence in streptomycin-resistant Pasteurella pestis. J. Bacteriol. 84:615-624. 1962.-Avirulence in Pasteurella pestis, as indicated by the existence of a new genotype, was associated with the genetic loss of Ca(++) dependence rather than with the usual concomitant loss of abilit...