绿盖粉孢牛肝菌中一个新的甾体糖苷

从绿盖粉孢牛肝菌（Tylopilus virens）中分离得到一个新的麦角甾烷型甾体糖苷,其化学结构通过波谱学方法鉴定为：（22E,24R）-麦角甾-7,22-二烯-5α,6β-二醇-3β-O-[3-（3-苯基丙酰氧基）]-β-D-葡萄吡喃糖苷,命名为tylopiloside（1）,同时,其苷元cerevisterol（2）也从该菌中分离得到。值得注意的是,这种糖片段上有芳环取代的烷酰氧基基团的麦角甾烷型甾体糖苷为真菌中首次报道。     

Clonostachys rosea,a potential biological control agent for Rhizoctonia solani AG-3 causing black scurf on potato

Rhizoctonia solani AG-3 forms sclerotia on potato tubers, reducing quality and marketability. Potato discs with sclerotia were exposed to saturated soil, and following toothpick baiting, hyphae of R. solani parasitised with mycelia that either coiled around or penetrated cell walls were observed. Similar parasitic behaviour was observed in dual cultures. Clonostachys rosea was identified as the mycoparasite by morphology and ITS sequencing. When co-inoculated onto stems grown from disease-free seed potatoes, tubers of the C. rosea?+?R. solani inoculated plants had significantly lower black scurf (P?0.0001) and higher yield (P?=?0.0002) than R. solani inoculated controls.     

Effect of peat-bran inoculum ofTrichoderma species on biological control ofRhizoctonia solani in lettuce

A range of known biocontrol or plant growth-stimulating species ofTrichoderma orGliocladium were grown on peat-bran substrate to yield between 5×10⁷–3×10¹⁰ colony forming units (cfu's)g^–1 substrate after 14 days growth. Inocula were incorporated into peat:sand potting compost infested withRhizoctonia solani to give 7–8 × 10⁴ cfu's of antagonist g^–1 compost and assessed for biological control activity using lettuce seedlings. Six of the eight antagonists decreased daming-off and three of these consistently increased yield in comparison withR. solani treatment alone.Subsequently, peat-bran inoculum ofT. harzianum isolate TH1 was incorporated at 0.5% w/v intoR. solani infested potting compost. Both autoclaved and nonautoclaved inoculum ofT. harzianum TH1 decreased disease and increased yield. Incorporation of ethyl acetate-extracted autoclaved inoculum ofT. harzianum TH1 resulted in similar levels of biocontrol and improved plant growth as did incorporation of nonautoclaved and autoclavedT. harzianum TH1 inoculum. The need to standardize inocula and controls is emphasized.     

Induction of cytoplasmic leakage from Rhizoctonia solani hyphae by Gliocladium virens and partial characterization of a leakage factor

The biocontrol fungus Gliocladium virens (Gl‐21)was grown on various solid and liquid substrates. Aqueous extracts of wheat bran and peanut hull meal (PHM)as well as spent glucose tartrate broth (GTB), Czapek‐Dox broth (CDB) and potato dextrose broth (PDB) upon which Gl‐21 was grown caused leakage of carbohydrates and electrolytes from hyphae of the soilborne plant pathogen Rhizoctonia solani. In addition, the mycelial weight of R. solani was reduced. Most of the leakage factor was formed in the substrates within six days of incubation. Acidification of the bran and the PHM media before inoculation stimulated production of the leakage factor by G. virens. Size‐fractionation experiments indicated that a combination of factors produced by G. virens induced leakage from R. solani. Although the < 1 k Da fraction from the water‐extracted bran culture contained significant leakage activity, it was less than in the non‐fractionated bran culture. The > 1 k Da fraction from bran culture did not induce leakage activity. When the < 1 k Da and the > 1 k Da fractions were recombined, leakage activity was restored to a level similar to that of the non‐fractionated preparation. Gliotoxin was detected in culture filtrates from G. virens grown on bran and PHM media. Gliotoxin preparations induced leakage of carbohydrates and electrolytes from R. solani and caused a concomitant reduction in mycelial weight, which suggests that it is a leakage factor.     

Biological control of onion neck rot (Botrytis aclada): Protection of wounds made by leaf topping

The efficacy of fungal antagonists in protecting onions from neck rot caused by Botrytis aclada was investigated. Leaf wounds made by topping of onions during harvest, which are considered as important entrance sites for B. aclada, were treated with conidial suspensions (5 × 10⁷ conidia ml^‐1) of antagonists. In field experiments with artificial inoculation with conidia of B. aclada, applications of Trichoderma viride during harvest reduced the incidence of neck rot, assessed after three months’ storage of the onions at 9° C, from 35% to 24% in 1989 and from 28% to 18% in 1990, when onions initially had been stored under favourable conditions for fungal development. Comparable results were obtained with T. hamatum and Gliocladium roseum. A bioassay based on wound treatment of detached onion leaves was developed to select further antagonists. From 40 candidate antagonists tested, 20 strains gave similar or better control than the strain of T. viride applied in the field experiments. Effective antagonists could be found amongst strains of Trichoderma spp. Gliocladium spp. and Penicillium spp. as well as amongst fungi such as Aureobasidium pullulans and yeasts isolated from green leaves of onion or rye.     

Exopolysaccharide from surface-liquid culture of <Emphasis Type="Italic">Clonostachys</Emphasis><Emphasis Type="Italic">rosea</Emphasis> originates from autolysis of the biomass

We describe the purification and chemical characterization of galactomannans that appear both in the biomass and the culture broth during surface-liquid culture of the fungus Clonostachys rosea, a common facultative saprophyte that has potential to be used as a biological control agent against several plant pathogenic fungi, insects and nematodes. The galactomannans from both sources had comparable ratios of Man, Gal and Glc and the similarity were confirmed by ¹H, ¹³C NMR, HMQC, and COSY spectra. We propose that the galactomannan in the culture broth originates from autolysis of the biomass, based not only on the similarity that it has with the galactomannan extracted from the biomass but also on the fact that its concentration increased rapidly after glucose depletion from the medium, when biomass concentration was falling. Polysaccharides from C. rosea have not previously been characterized; we show that the characteristics of the galactomannans are consistent with those that have been reported for other members of the Bionectriaceae, the family to which C. rosea belongs.     

Diurnal patterns in the spatial relationships between saithe, Pollachius virens, schooling in the wild

Six saithe, length 35 to 43 cm, were tagged with acoustic transmitters and individuals tracked for between 9 and 508 h during May 1989. The tagged fish were members of a schooling group and during the study, pairs of tagged fish were tracked simultaneously for periods ranging from 9 to 139 h. These data have been used to investigate the spatial relationships between individuals schooling in the wild. Distances between individuals showed a distinct diel pattern. Tagged fish were generally closer together during the day, than either at night or the periods of dawn and dusk. Those circumstances under which pairs of tagged fish could be shown to school together were investigated by analysing the differences in their swimming directions. Schooling was generally evident during the hours of daylight, although the degree to which fish schooled varied between pairs. The degree to which the fish schooled was also dependent upon distance between the tagged individuals. Schooling could be demonstrated for saithe within 20 m of each other during the day and within 10 m in two out of three pairs at night.     

Evaluation of Gliocladium roseum Against Wood-Degrading Fungi in vitro and on Major Canadian Wood Species

The protection of wood from fungal stain using biological agents has considerable potential for reducing discoloration of freshly sawn logs and lumber, while decreasing fungicide use. A number of biocontrol candidates have been reported worldwide, and Gliocladium roseum is one of such microorganisms. In this study, the bio-activity of G. roseum was investigated against different wood-degrading fungi on agar plates and wafers of 12 major Canadian wood species. Of the four sap-staining fungi tested on agar plates, Ophiostoma piceae and Alternaria alternata showed greater sensitivity than Aureobasidium pullulans or Cladosporium sphaerospermum to G. roseum . On wood wafers, a spore suspension of G. roseum (1 10 6 spores/ ml) provided satisfactory protection of wood from stain on western hemlock ( Tsuga heterophylla ), white spruce ( Picea glauca ), amabilis fir ( Abies amabilis ), balsam fir ( Abies balsamea ) and jack pine ( Pinus banksiana ). The antagonist also restricted the development of moulds and stain on black spruce ( Picea mariana ), lodgepole pine ( Pinus contorta ) and white pine ( Pinus strobus ), but did not protect Douglas fir ( Pseudotsuga menziesii ), red pine ( Pinus resinosa ), white birch ( Betula papyrifera ) and trembling aspen ( Populus tremuloides ). Logs of black spruce and jack pine treated with G. roseum were much less stained than untreated ones after a 4-month period of summer storage in the field. In an anti-decay test, no significant difference was found for weight loss between wood blocks treated with G. roseum and untreated samples. Application of G. roseum with low levels of an anti-sap stain chemical (NP-1) to wood wafers simultaneously did not produce a noticeable improvement in wood protection against stain compared with the chemical treatment alone.     

Hydroacoustic measurement of swimming speed of North Sea saithe in the field

Saithe Pollachius virens , tracked diurnally with a split-beam echosounder, showed no relationship between size and swimming speed. The average and the median swimming speeds were 1·05 m s⁻¹(±0·09 m s⁻¹) and 0·93 m s⁻¹, respectively. However, ping-to-ping speeds up to 3·34 m s⁻¹ were measured for 25–29 cm fish, whose swimming speeds were significantly higher at night (1·08 m s⁻¹) than during the day (0·72 m s⁻¹). The high average swimming speed could be related to the foraging or streaming part of the population and not to potential weakness of the methodology. However, the uncertainty of target location increased with depth and resulted in calculated average swimming speeds of 0·15 m s⁻¹ even for a stationary target. With increasing swimming speed the average error decreased to 0 m s⁻¹ for speeds >0·34 m s⁻¹. Species identity was verified by trawling in a pelagic layer and on the bottom.     

Viability of Heterodera glycines Exposed to Fungal Filtrates

Filtrates from nematode-parasitic fungi have been reported to be toxic to plant-parasitic nematodes. Our objective was to determine the effects of fungal filtrates on second-stage juveniles and eggs of Heterodera glycines. Eleven fungal species that were isolated from cysts extracted from a soybean field in Florida were tested on J2, and five species were tested on eggs in vitro. Each fungal species was grown in Czapek-Dox broth and malt extract broth. No toxic activity was observed for fungi grown in Czapek-Dox broth. Filtrates from Paecilomyces lilacinus, Stagonospora heteroderae, Neocosmospora vasinfecta, and Fusarium solani grown in malt extract broth were toxic to J2, whereas filtrates from Exophiala pisciphila, Fusarium oxysporum, Gliocladium catenulatum, Pyrenochaeta terrestris, Verticillium chlamydosporium, and sterile fungi 1 and 2 were not toxic to J2. Filtrates of P. lilacinus, S. heteroderae, and N. vasinfecta grown in malt extract broth reduced egg viability, whereas F. oxysporum and P. terrestris filtrates had no effect on egg viability.