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Characterization of the mycoparasite Coniothyrium minitans: comparison between morpho-physiological and molecular analyses
No full textEight strains of the mycoparasite Coniothyrium minitans were analysed for intraspecific variation by three different approaches: analysis of morpho-physiological characteristics; random amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) analysis of the genomic DNA. A high variability in colony colour, gross morphology and conidial size was found depending on strain and culture conditions. All individual strains could be distinguished using the three type of analyses. However, a close correspondence between RAPD, AFLP patterns and morpho-physiological characteristics of C. minitans strains was not observed. Our results suggest AFLP analysis constituted a more efficient and reliable tool than RAPD analysis or morpho-physiological studies to detect intraspecific variability in C. minitans and to follow its fate after application in the field
An improved method for the detection of Phytophthora cactorum (l. C.) Schroeter in infected plant tissues using SCAR markers
No full textPhytophthora cactorum (Lebert et Cohn) Schroeter is an important plant pathogen that can cause serious damage in agricultural and ornamental crops as well as in a wide range of forest species. The identification of this pathogen, based on morphological and physiological characters, is time consuming, labour-intensive and requires specialised staff to be correctly performed. Recently, PCR-based methods have partially resolved these problems, but the primers used cross react with Phytophthora idaei. To prevent any such reaction the use of a new pair of primers (PC1/PC2) with improved specificity, derived from a specific Random Amplified Polymorphic DNA (RAPD) generated fragment, is proposed. The PC1/PC2 primers, used in a simple PCR protocol, gave a single amplification product of approximately 450 bp; a good degree of specificity, with absence of cross reactions with Phytophthora pseudotsugae and R idaei; sensitivity down to 6 pg of R cactorum DNA extracted from pure mycelium; no reactions with the DNA of the host plants tested (downy oak, pear and walnut trees, potato, strawberry, tomato and pea plants). The detection of R cactorum in infected tissues of pear and walnut trees, potato, strawberry, tomato and pea plants was also confirmed. The specificity, sensitivity and robustness of the PC1/PC2 primers together with the possibility of their use in a rapid, simple and reliable diagnostic method are discussed
Characterization of the mycoparasite coniothyrium minitans: Comparison between morpho-physiological and molecular analyses
No full textEight strains of the mycoparasite Coniothyrium minitans were analysed for intraspecific variation by three different approaches: analysis of morpho-physiological characteristics; random amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) analysis of the genomic DNA. A high variability in colony colour, gross morphology and conidial size was found depending on strain and culture conditions. Ali individual strains could be distinguished using the three type of analyses. However, a close correspondence between RAPD, AFLP patterns and morpho-physiological characteristics of C. minitans strains was not observed. Our results suggest AFLP analysis constituted a more efficient and reliable tool than RAPD analysis or morpho-physiological studies to detect intraspecific variability in C. minitans and to follow its fate after application in the field. © 2002 Elsevier Science Ltd. All rights reserved
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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