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The Fusarium oxysporum species complex ( FOSC) causes disease in plants and animals, but is also widely dispersed in natural ecosystems without evidence of disease. The present study screened a population representing natural ecosystems across the Australian continent for the putative effector genes pisatin demethylase 1 ( PDA1), pectate lyase ( pelD), secreted gene expression ( SGE1) and secreted in xylem ( SIX). The genes pelD and SGE1 were prevalent in the natural isolates, PDA1 was present at an intermediate level, whereas SIX genes were detected at low levels. Phylogenies of these putative effector genes were compared to the EF-1α species phylogeny to determine the likely modes of gene transmission: vertical gene transfer ( VGT) and horizontal gene transfer ( HGT). There was evidence of both modes of gene transmission within the F. oxysporum isolates. PDA1, pelD and SGE1 were likely to be only vertically inherited, whereas the SIX genes had evidence for both VGT and HGT. The phylogenetic relationships of SIX genes in isolates from natural ecosystems and formae speciales from agro-ecosystems were also established. These findings have important implications for the evolution of effectors in the FOSC. [ABSTRACT FROM AUTHOR]

The objective of the present study was to evaluate the effects of different gamma radiation doses on the growth of Alternaria alternata and on the production of toxins alternariol (AOH), and alternariol monomethyl ether (AME) in sunflower seed samples. After irradiation with 2, 5 and 7 kGy, the spore mass was resuspended in sterile distilled water and the suspension was inoculated into sunflower seeds. The number of colony-forming units per gram (CFU/g) was determined after culture on Dichloran Rose Bengal Chloramphenicol and Dichloran Chloramphenicol Malt Extract Agar. The presence of AOH and AME was investigated by liquid chromatography coupled to mass spectrometry. The radiation doses used resulted in a reduction of the number of A. alternata CFU/g and of AOH and AME levels when compared to the nonirradiated control group. Maximum reduction of the fungus (98.5%) and toxins (99.9%) was observed at a dose of 7 and 5 kGy, respectively. Under the present conditions, gamma radiation was found to be an alternative for the control of A. alternata and, consequently, of AOH and AME production in sunflower seeds.

The objective of this study was to evaluate the effects of different gamma-radiation doses on the growth of Alternaria alternata in artificially inoculated cereal samples. Seeds and grains were divided into four groups: Control Group (not irradiated), and Groups 1, 2 and 3, inoculated with an A. alternata spore suspension (1 x 10(6) spores/mL) and exposed to 2, 5 and 10 kGy, respectively. Serial dilutions of the samples were prepared and seeded on DRBC (dichloran rose bengal chloramphenicol agar) and DCMA (dichloran chloramphenicol malt extract agar) media, after which the number of colony-forming units per gram was determined in each group. In addition, fungal morphology after irradiation was analyzed by scanning electron microscopy (SEM). The results showed that ionizing radiation at a dose of 5 kGy was effective in reducing the growth of A. alternata. However, a dose of 10 kGy was necessary to inhibit fungal growth completely. SEM made it possible to visualize structural alterations induced by the different gamma-radiation doses used.

The aim of this study was to determine the clinical, pathological and mycotoxicological effects of oral administration of fumonisin B1 (FB1) in rabbits. Eighteen rabbits were randomly assigned to two experimental groups: control group, 0 mg FB1; fumonisin group, 31.5 mg FB1/kg body weight, corresponding to about 630 mg FB1/kg diet. Fumonisin administered as a single oral dose to rabbits resulted in acute toxicity, significantly interfering with body and liver weight. Serum biochemical analysis revealed a significant increase of total protein, alkaline phosphatase (AP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyltransferase (GGT), urea and creatinine in the group receiving FB1 compared to control animals, a finding characterizing hepatic and renal injury in this group. Urinary protein concentrations were markedly elevated at 12, 24, 48 and 72 h after dosing, although visible pathological abnormalities were not observed, probably because of rapid repair of the damage. FB1 was detected in feces, with a maximum concentration at 24 h after administration, indicating that the enterohepatic circulation is important in rabbits. FB1 concentrations found in urine were low, with peak elimination at 12 h after intoxication. The highest FB1 concentrations were observed in feces compared to urine and liver, demonstrating that feces are the main routes of excretion.