0000000000323343
AUTHOR
Hubert Dulieu
Modes d’invasion et d’expression de Botrytis cinerea, champignon pathogène de la Vigne
Introduction : Le champignon phytopathogene Botrytis cinerea est un polyphage qui cause d'enormes degâts en agriculture. La culture de la vigne represente en France des enjeux economiques importants. La vigne est touchee par la maladie de la pourriture grise due a B. cinerea, conduisant a des pertes de rendement importantes. L'objectif de cette etude est, compte tenu des effets sur le developpement fongique de facteurs environnementaux (Sautour et al., 2001a, b), la caracterisation du caractere pathogene et la comparaison des structures de populations de B. cinerea isolees de differentes regions de France : Bourgogne, Languedoc et Champagne. Materiel et methodes : Les suspensions de conidie…
Tobacco plants detect a decrease of environmental genotoxicity in Toulouse (France).
Tobacco plants, heterozygous for two independent loci involved in the chlorophyll parenchyma differentiation, allow the genotoxic effects of the atmosphere of the industrial estate South of Toulouse to be estimated. Somatic spots of green cellular colonies on yellow-green background, were counted to calculate the cellular rates of reversion. Two experiments were carried out in 1981, and in 1997. A general decrease of genotoxic effects was observed. These observations were interpreted as being due to a general decrease of the air pollution evaluated by the development of the concentrations of three toxic gases before and after the implementation of cleanup devices. The results obtained demon…
A new species of Pythium isolated from the Burgundy region in France.
Pythium nodosum sp. nov. has been isolated from a soil sample taken in the Burgundy region in France. The fungus has spherical to variously shaped proliferating sporangia, smooth-walled oogonia which are crowded with different antheridial branches making a complicated knot around the former, and aplerotic oospores. Morphological and reproductive aspects of Pythium nodosum as well as the PCR of the internal transcribed spacer (ITS1) of the ribosomal nuclear DNA coupled with restriction fragment length polymorphism analysis are described here. The nucleotide sequences of ITS1 encoding 5.8S rRNA is also given.
Base composition of DNA from glomalean fungi: high amounts of methylated cytosine.
Glomales (Zygomycetes) are obligate fungal symbionts of roots of land plants and form arbuscular mycorrhiza. Sporal DNA of 10 isolates belonging to nine species was purified and the base composition was determined by RP-HPLC. Base composition fell in a narrow range between 30 and 35% G + C. A high amount of methylated cytosine (mC) accounting for 2-4% of the total nucleotides was found in all taxa. The DNA melting profile was defined for Scutellospora castanea. It corresponded to 32% G + C, and the shape of the denaturation curve suggested a heterogeneity in the GC content within the fungal genome. Knowledge of GC contents and variations between taxa are essential for evaluating nuclear DNA…
Biodiversity and characterization of arbuscular mycorrhizal fungi at the molecular level
Biodiversity within a biological group provides the basis for distinguishing members into genera and species according to taxonomic criteria, and between individuals within a species depending on more detailed differences at the genetic level. Diversity between species occurs after a genetic barrier has been created either by a geographic or genetic impedance of gene flow. Divergence can continue by nucleotide substitutions and by mutations in a broader sense (deletions, translocations, duplications), and resulting diversity can be evaluated at the molecular level and used as a phylogenetic character. Diversity at the subspecies level is a function of both mutation rates and gene flow betwe…