RESUMO
Brown root rot of alfalfa (Medicago sativa), caused by Phoma sclerotioides, has been reported in several states in the northern United States and in western Canada. A survey was conducted to determine the distribution of the fungus in Minnesota and Wisconsin. Isolates of the pathogen were recovered from roots of alfalfa, winter wheat, and perennial ryegrass plants. The internal transcribed spacer (ITS) 1, 5.8S, and ITS2 of the rDNA of the isolates from alfalfa and wheat were identical and matched the sequences of a P. sclerotioides isolate from Wyoming. The fungus was found to be widespread in both states and was detected in roots of alfalfa plants from 17 counties in Minnesota and 14 counties in Wisconsin using polymerase chain reaction (PCR)-based assays. A real-time PCR assay was developed that increased sensitivity of detecting the pathogen from plant tissues and soil. The isolates from alfalfa caused disease on inoculated winter wheat plants. Although the fungus was previously found associated with roots of diseased cereal and turfgrass plants, this is the first demonstration of pathogenicity of P. sclerotioides on wheat.
RESUMO
Livestock deaths, and clinical reports of human injury, follow the consumption of toxic blue-green algae. The experiments described show that isolated intestinal enterocytes from chicks are both deformed and killed by exposure to Microcystis toxins, in a dose-dependent and time-dependent manner. The enterocytes were protected from toxicity by deoxycholate, bromosulphothalein and rifampicin. It was concluded that the gastroenteritis clinically associated with accidental Microcystis ingestion is likely to reflect enterocyte injury by Microcystis toxins, and that the therapeutic use of bile acids or transport inhibitors may be of value in treatment.
