Application of molecular methods for characterization of Phoma and Ascochyta species of legumes

International audienc

Apport des techniques biochimiques et moléculaires pour la caractérisation des champignons pathogènes des légumineuses à grosses graines, dans les pays du pourtour méditerranéen.

International audienc

Cultural, molecular and pathogenic variability of Mycosphaerella pinodes and Phoma medicaginis var. pinodella isolates from dried pea (Pisum sativum) in France

International audienc

Distribution of large-spored Alternaria species associated with early blight of potato and tomato in Algeria

Potato and tomato are important crops in Algerian agriculture, and both are threatened by abiotic and biotic stresses, and early blight is a major disease affecting both crops. Surveys carried out from 2012 to 2015 in 12 major growing regions for these crops yielded a total of 247 Alternaria isolates having morphological and cultural characteristics of sections Alternaria and Porri. Since early blight symptoms and morphological characteristics of the isolates did not allow sharp distinction between the different large-spored species of Alternaria, the isolates in section Porri, often considered primary causes of the diseases, were selected for molecular characterization by diagnostic PCR using specific primers. This allowed species identification of 147 Alternaria isolates as A. solani, A. protenta, A. grandis or A. linariae. These species were present on potato and tomato crops at varying frequencies, depending on the hosts and on bioclimatic locations. Pathogenicity tests for the four species, on detached leaflets and whole seedlings, showed that all were pathogenic to potato and tomato, with varying virulence. These results suggest that parasitic specialization of these Alternaria species on solanaceous plants should be reconsidere

Ascochyta blight of chickpea in Australia: identification, pathogenicity and mating type

International audienc

Développement d'une méthode de diagnostic de Mycosphaerella pinodes pour améliorer la qualité sanitaire des semences de pois

International audienc

Isolation of atypical wheat-associated xanthomonads in Algeria

Bacterial leaf streak and black chaff are important bacterial diseases of wheat, which have been reported to be caused by Xanthomonas translucens. In 2016, symptoms of bacterial leaf streak and black chaff were observed in Algeria, at experimental wheat breeding stations and in farmers' fields under sprinkler irrigation on two wheat cultivars, 'Hiddab' and 'Simeto'. Yellow Xanthomonas-like bacterial colonies were isolated from plant material, including leaves, spikes and post-harvest crop residues. Initial characterisation using biochemical, physiological and pathogenicity tests identified the bacteria as Xanthomonas. Diagnostic PCR targeting the 16S-23S rRNA intergenic region indicated that the strains were X. translucens, a clade-1 xanthomonad. However, partial DNA sequences of the housekeeping genes gyrB and rpoD revealed that the strains belong to clade 1, but likely represent a new Xanthomonas species that has not been previously described on wheat or other Gramineae. The most closely related strain, NCPPB 2654, was isolated from a bean plant in the United Kingdom in 1974. Further characterization is required to clarify the taxonomic status of the Algerian Xanthomonas isolates from wheat, and to determine their host ranges and impacts on plant cultivation

Phenotypic and biochemical characterization of new advanced durum wheat breeding lines from Algeria that show resistance to fusarium head blight and to mycotoxin accumulation

International audienceDurum wheat (Triticum turgidum L. var. durum) is a crop highly susceptible to Fusarium head blight (FHB), which results in yield losses and downgrades the quality of grains mostly due to mycotoxin contamination. Although breeding for resistance to FHB is one of the most promising strategy for minimizing crop damage, the attempts to obtain durum wheat resistant lines have been limited so far. Two potentially interesting lines were recently delivered by a breeding program based on crosses involving cultivars from Europe and Syria. Using a field experiment in Algeria with four different Fusarium culmorum strains and a spray inoculation method, we demonstrated that the two breeding lines were significantly less affected than a set of commercial cultivars. The two breeding lines were shown to exhibit a higher resistance to both initial fungal infection and disease spread , and to mycotoxin contamination. In addition, a detailed analysis of 2 phenolic acid composition of grains indicates significant differences in p-coumaric acid between the FHB-resistant breeding lines and the sensitive genotypes. Our results corroborate the importance of cell wall composition in preventing the diffusion of F. culmorum and therefore contributing to the resistance of cereals to FHB