“Fusarium species belonging to the Fusarium fujikuroi species complex (FFSC) are associated with maize in northern Mexico and cause Fusarium ear and root rot. In order to assess the diversity of FFSC fungal species involved in this destructive disease in Sinaloa, Mexico, a collection of 108 fungal isolates was obtained from maize plants in 2007–2011. DNA sequence analysis of the calmodulin and elongation factor 1α genes identified BIBW2992 clinical trial four species: Fusarium verticillioides, F. nygamai, F. andiyazi and F. thapsinum (comprising 79, 23, 4 and 2 isolates, respectively).
Differential distribution of Fusarium species in maize organs was observed, that is F. verticillioides was the most frequently isolated species from maize seeds, while F. nygamai
predominated on maize roots. Mixed infections with F. verticillioides/F. thapsinum and F. verticillioides/F. nygamai were detected in maize seeds and roots, respectively. Pathogenicity assay demonstrated the ability of the four species to infect maize seedlings and induce different levels of disease severity, reflecting variation in aggressiveness, plant height and root biomass. Isolates of F. verticillioides and F. nygamai were the most aggressive. These species were able to colonize all root tissues, from the epidermis to the vascular vessels, while infection by F. andiyazi and F. thapsinum was restricted to C59 wnt mw the epidermis and adjacent cortical cells. This is the first report of F. nygamai, F. andiyazi and F. thapsinum infecting maize in Mexico and co-infecting with F. verticillioides. Mixed infections should be taken into consideration due to the production and/or accumulation of diverse mycotoxins in maize grain. “
“The penetration behaviour
of the pathogen Venturia nashicola, which causes scab disease in Asian 上海皓元 pears, was studied at the ultrastructural and cytochemical levels in host and non-host leaves. We show, for the first time, that before V. nashicola penetrated the cuticle of the epidermis of the pear leaf, the appressorial bottom of the pathogen invaginated to form a cavity that contains electron-dense material. The leaf cuticle beneath the cavity also became highly electron dense following penetration by V. nashicola. The location of these electron-dense materials at the sites of penetration of the pathogen into plant cell walls suggests that they might be related to enzymes capable of degrading cell walls and that the cavities might be needed for successful penetration of leaves by V. nashicola. The generation of hydrogen peroxide (H2O2) was observed in penetration-related infection structures of V. nashicola, such as appressorial bottoms, infection sacs, penetration pegs and necks of subcuticular hyphae regardless of whether the interaction of V. nashicola with pear plants was compatible or incompatible. Nonetheless, more H2O2 was generated at the sites of the structures in scab-inoculated susceptible leaves than that in scab-inoculated resistant ones.