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Examines the specificity of polymerase chain reaction primers to the rape seed pathogen Leptosphaeria maculans. Differentiation of DNA bands between isolates; Determination of group-specificity pathogenicity; Use of chemical and dideoxynucleotide chain termination methods.

Oilseed rape (Brassica napus) is attacked by many parasitic fungi which often occur in mixed infections. Monitoring of these phytopathogens by morphological criteria is restricted due to their appearance especially in the later stages of disease development. We have developed molecular markers for a clear-cut differentiation of a variety of rape seed pathogenic fungi based on randomly amplified polymorphic DNA (RAPD). Twenty polymorphic fragments have been selected in Southern hybridization experiments to test their taxon-specificity. in summary, only four amplification products gave unspecific cross-hybridization patterns, one fragment corresponds to a genetic element common to three species within the genus Alternaria, and 15 RAPD markers were highly specific for distinct fungal species. This report demonstrates the value of the RAPD-PCR technique to amplify taxon-specific DNA fragments that can be used as hybridization probes for the diagnosis of a variety of rape seed pathogens (Alternaria brassicae, A. brassicicola, A. raphani; Cylindrosporium concentricum; Fusarium moniliforme; Phoma ligam; Phythium sp.; Rhizoctonia solani; Sclerotinia sclerotiorum; Verticillium dahliae, V. latericium) [ABSTRACT FROM AUTHOR]

RNA polymerase-binding protein A (RbpA), encoded by Rv2050, is specific to the actinomycetes, where it is highly conserved. In the pathogen Mycobacterium tuberculosis, RbpA is essential for growth and survival. RbpA binds to the β subunit of the RNA polymerase where it activates transcription by unknown mechanisms, and it may also influence the response of M. tuberculosis to the current frontline anti-tuberculosis drug rifampicin. Here we report the solution structure of RbpA and identify the principle sigma factor σ(A) and the stress-induced σ(B) as interaction partners. The protein has a central ordered domain with a conserved hydrophobic surface that may be a potential protein interaction site. The N and C termini are highly dynamic and are involved in the interaction with the sigma factors. RbpA forms a tight complex with the N-terminal domain of σ(B) via its N- and C-terminal regions. The interaction with sigma factors may explain how RbpA stabilizes sigma subunit binding to the core RNA polymerase and thereby promotes initiation complex formation. RbpA could therefore influence the competition between principal and alternative sigma factors and hence the transcription profile of the cell.