28s rDNA group-I introns: a powerful tool for identifying strains of Beauveria brongniartii

The nuclear ribosomal DNA of the entomopathogenic fungus Beauveria brongniartii is polymorphic in terms of both restriction site and length. Insertions of 350–450 bp long, identified as group-I introns, were detected in the 28 s rDNA. A panel of 47 strains of B. brongniartii , two B. bassiana and one Metarhizium anisopliae of various geographical and biological origins were found to contain 14 variant forms of intron differing in size and restriction pattern, at four different positions. Twelve types of ribosomal large subunit were defined on the basis of variant distribution and compared with strain clustering based on internal transcribed spacers analysis. There was a correlation between the characteristic introns and isolates collected from the sugar cane pest Hoplochelus marginalis . Primers for polymerase chain reaction amplification were chosen from these variants, and used to develop a specific method for detecting strains pathogenic towards Hoplochelus .     

Isolation of the transposable element hupfer from the entomopathogenic fungus Beauveria bassiana by insertion mutagenesis of the nitrate reductase structural gene

A transposable element has been isolated from the entomopathogenic fungus Beauveria bassiana by trapping it in the nitrate reductase structural gene, which has been cloned from this species. The element had inserted in the first exon of the nia gene and appeared to have duplicated the sequence TA at the site of insertion. It was 3336 bp long with 30-bp imperfect, inverted, terminal repeats. The element, called hupfer, contained an open reading frame encoding a 321-amino acid protein similar to the IS630- or mariner-Tc1-like transposases, and a residual sequence of about 2 kb which was not significantly similar to any published sequence. There are fewer than five copies of this transposable element present per genome in the fungus. Received: 12 February 1997 / Accepted: 2 May 1997     

Increase in proteinase activity in the cellular slime mould Polysphondylium pallidum induced by bacteria

Abstract Polysphondylium pallidum strain PPHU8 grown in association with bacteria contains aspartic and cysteine proteinases. When myxamoebae were grown in axenic medium the contribution of cysteine proteinases was much lower. The proteinase activity could be altered by addition of heat-killed bacteria to axenically growing cells. This was detected as an increase in the specific activity towards N -benzoyl-L-prolyl-L-phenylalanyl-L-arginine- p -nitroanilide, a cysteine proteinase substrate, and by the appearance of cysteine proteinase bands after electrophoretic analysis. The changes were inhibited by cycloheximide, azide and dinitrophenol. All the available evidence suggests that they are due to the de novo synthesis of cysteine proteinases.     

Charakterisierung extrazellulärer proteine und enzyme aus pektinkulturfiltraten von Botrytis cinerea

Extracellular proteins from Botrytis cinerea CBS 144.55 were separated by use of isoelectric focusing in polyacrylamide gel and thin layer isoelectric focusing. In addition to the protein pattern, the activities of protease, amylase, cellulase, polygalacturonase, pectinesterase and glycosidases were determined.     

Benomyl Tolerance of Ten Fungi Antagonistic to Plant-parasitic Nematodes

Ten strains of fungi were tested for tolerance to the fungicide benomyl. Verticillium chlamydosporium strain 2 did not grow in the presence of benomyl; Drechraeria coniospora strains 1 and 2 and Chaetomium sp. tolerated only 0.1 μg benomyl/ml medium; Acremonium bacillisporum, an unidentified fungus, and Phoma chrysanthemicola uniformly grew at 1 μg/ml, but some hyphae grew at higher benomyl concentrations; Fusarium sp. tolerated 475 μg/ml, but some hyphae grew on medium amended with 1,000 μg/ml; Verticillium lecanii and V. chlamydosporium strain 1 routinely tolerated 1,000 μg/ml. Fungi generally grew more slowly at higher than at lower benomyl concentrations. Strains with elevated tolerance to benomyl were selected from Acremonium bacillisporum, Drechmeria coniospora, Fusarium sp., and an unidentified fungus. These strains retained the increased tolerance after repeated transfers on unamended medium.     

Effects of Rapeseed and Vetch as Green Manure Crops and Fallow on Nematodes and Soil-borne Pathogens

In a rapeseed-squash cropping system, Meloidogyne incognita race 1 and M. javanica did not enter, feed, or reproduce in roots of seven rapeseed cultivars. Both nematode species reproduced at low levels on roots of the third crop of rapeseed. Reproduction of M. incognita and M. javanica was high on squash following rapeseed, hairy vetch, and fallow. The application of fenamiphos suppressed (P = 0.05) root-gall indices on squash following rapeseed, hairy vetch, and fallow; and on Dwarf Essex and Cascade rapeseed, but not Bridger and Humus rapeseed in 1987. The incorporation of 30-61 mt/ha green biomass of rapeseed into the soil 6 months after planting did not affect the population densities of Criconemella ornata, M. incognita, M. javanica, Pythium spp., Rhizoctonia solani AG-4; nor did it consistently increase yield of squash. Hairy vetch supported larger numbers of M. incognita and M. javanica than rapeseed cultivars or fallow. Meloidogyne incognita and M. javanica survived in fallow plots in the absence of a host from October to May each year at a level sufficient to warrant the use of a nematicide to manage nematodes on the following susceptible crop.     

The effect of introducing the aphid-pathogenic fungus Erynia neoaphidis into populations of cereal aphids

The aphid-pathogenic fungus Erynia neoaphidis, as dried fungus-infected aphids, was applied to caged plots of winter wheat infested with cereal aphids at two sites, one in Hertfordshire and the other in Hampshire, in 1983. In each trial, the fungus became established in the aphid populations in the treated plots even though conditions were drier than average and therefore sub-optimal for fungus spread. Treatment applied in the third week of June increased the proportion of infected aphids more than that applied two weeks later at one site, and the early application was the only treatment to have an obvious effect at the other. In spite of the observed effect of treatments on the proportion of infected aphids, the fungus failed to reduce the numbers of aphids relative to those in untreated plots, chiefly because in these plots many aphids were killed by fungi of the same species as that introduced and other related species from natural sources. Artificial introduction of E. neoaphidis acts too slowly and unpredictably to be likely to form a practical alternative to conventional insecticides for cereal aphid control.     

Ligninolytic activity and levels of ammonia assimilating enzymes in Sporotrichum pulverulentum

Levels of ammonia-assimilating enzymes (glutamate dehydrogenase, glutamine synthetase, glutamate synthase) were determined in extracts of Sporotrichum pulverulentum grown under different conditions with respect to both nitrogen source and concentration. Evolution of ¹⁴CO₂ from ¹⁴C-synthetic lignin by fungal cultures grown under parallel conditions was also determined as a measure of lignin decomposition and the suppressive effect of nitrogen on ligninolysis confirmed. Under low nitrogen conditions, fungal extracts exhibited relatively high levels of NADP-dependent glutamate dehydrogenase and glutamine synthetase dehydrogenase. Conversely, in high nitrogen extracts, lower levels of NADP-dependent glutamate dehydrogenase and glutamine synthetase activity, and higher levels of NAD-dependent glutamate dehydrogenase, were recorded. Possible effects of enzyme activities on intracellular pool concentrations of glutamate/glutamine, and the implications for the regulation of lignin metabolism, are discussed.A preliminary report was presented at The Ekman Days 1981, International Symposium on Wood and Pulping Chemistry, Stockholm, Sweden, June 9–12, 1981.