Hyperparasites of the genus shape Ampelomyces on powdery mildew fungi in Serbia

From 1982 to 1996, in Serbia, 229 species of plants infected with powdery mildew were collected. Seventy-five species had hyperparasites of the genus Ampelomyces. Distribution analysis showed that hyperparasitism was greatest on plants from the families Asteraceae, Apiaceae and Fabaceae. Ampelomyces was not found on the family Poaceae. It was reported for the first time on the families Amygdalaceae, Cornaceae, Grossulariaceae, Plantaginaceae, Rhamnaceae and other 37 plant species. Hyperparasites of the genus Ampelomyces were found on 33 different species of fungi that are causal agents of powdery mildews. They are reported for the first time on nine species. Pycnidial size varied in the range 45–106 × 25.5–40.5 μm and conidia from 4.5–10.5 × 2.5–4.8 μm. This revised version was published online in June 2006 with corrections to the Cover Date.     

Characterization of six polymorphic microsatellite loci from Ampelomyces quisqualis,intracellular mycoparasite and biocontrol agent of powdery mildew

Ampelomyces spp. are common intracellular mycoparasites of powdery mildews worldwide and a strain has been commercialized as a biocontrol agent against these plant pathogens. In light of recent genetic analyses revealing high internal transcribed spacer sequence variability among Ampelomyces strains on different host plant mildews, yet no sequence variability within the Malus strain, polymorphic microsatellites were required to permit biocontrol and ecological studies of the complex apple/apple mildew/Ampellomyces tritrophic interaction. For this purpose, described here are the primers to amplify six polymorphic microsatellite loci from Ampelomyces quisqualis isolated from mycelia of the apple powdery mildew fungus, Podosphaera leucotricha.     

Effects of elevated atmospheric CO2 and temperature on the management of powdery mildew of zucchini

The impact of combined environmental factors, such as temperature and CO₂, on the control of the powdery mildew of zucchini, caused by Podosphaera xanthii, and of different control measures has been studied on plants grown in phytotrons. Five experimental trials were conducted, and the powdery mildew severity of both treated and untreated zucchini plants was found to be significantly affected by the interaction between temperature (three different regimes: 16–18; 18–22; 22–26°C), CO₂ (two concentrations: 400–450 and 800–850 ppm) and the treatments. However, at the end of the trials, the efficacy of all the products was not affected by the different, tested environmental conditions. Sulphur consistently provided the highest disease control (75%–85% efficacy). Among the resistant inducers that were tested, calcium oxide was the most effective, in terms of powdery mildew control under all the conditions tested in phytotrons, reducing disease severity from 46% to 61%. Foliar applications of phosphite (14%–28% efficacy), Ampelomyces quisqualis (12%–23% efficacy) and potassium silicate (13%–24% efficacy) only slightly reduced the disease severity for all the tested temperature regimes and CO₂ concentrations, compared to the untreated control. The results obtained under our experimental conditions show that a possible increase in CO₂ concentration and temperature, which is expected for the next few years, should not influence the efficacy of the tested resistance inducers or of sulphur against powdery mildew on zucchini. Moreover, the suppressive effect of calcium oxide is in light of its possible use in greenhouses for zucchini powdery mildew control under 400–450 ppm of CO₂ and under enriched condition of 800–850 ppm of CO₂.     

香薷白粉病菌及其重寄生菌的分离鉴定

对采自中国长春香薷白粉病菌进行系统观察和测量,鉴定其为本间白粉菌(Erysiphe hommae Braun),同时发现了重寄生菌——白粉寄生孢（Ampelomyces quisqualis Ces.）,并对重寄生茵的叶部寄生特征及培养特征进行了描述.室内检测结果表明,重寄生菌的重寄生强度较高,可抑制白粉病的发生.     

Heteroatom-Containing Antibacterial Phenolic Metabolites from a Terrestrial Ampelomyces Fungus

Two new sulfur-containing phenolic compounds, 7-hydroxy-5-hydroxymethyl-2H-benzo[1,4]thiazin-3-one (1) and 2,5-dihydroxy-3-methanesulfinylbenzyl alcohol (2), along with two known compounds, 3-chloro-2,5-dihydroxybenzyl alcohol (3) and 2-hydroxy-6-methylbenzoic acid (4), were isolated from the mycelial solid culture of a soil-derived Ampelomyces fungus by antibacterial assay-guided fractionation. Their structures were elucidated on the basis of spectroscopic analysis. Compounds 1–3 showed structure and microbial dependent antibacterial activities.     

Bioactive metabolites from the endophytic fungus Ampelomyces sp. isolated from the medicinal plant Urospermum picroides

Extracts of cultures grown in liquid or on solid rice media of the fungal endophyte Ampelomyces sp. isolated from the medicinal plant Urospermum picroides exhibited considerable cytotoxic activity when tested in vitro against L5178Y cells. Chromatographic separation yielded 14 natural products that were unequivocally identified based on their ¹H and ¹³C NMR as well as mass spectra and comparison with previously published data. Six compounds (2, 4, 5, 7, 9 and 11) were natural products. Both fungal extracts differed considerably in their secondary metabolites. The extract obtained from liquid cultures afforded a pyrone (2) and sulfated anthraquinones (7 and 9) along with the known compounds 1, 3, 6 and 8. When grown on solid rice medium the fungus yielded three compounds 4, 5 and 11 in addition to several known metabolites including 6, 8, 10, 12, 13 and 14. Compounds 4, 8 and 10 showed the strongest cytotoxic activity against L5178Y cells with EC₅₀ values ranging from 0.2–7.3 μg/ml. Furthermore, 8 and 10 displayed antimicrobial activity against the Gram-positive pathogens, Staphylococcus aureus, S. epidermidis and Enterococcus faecalis at minimal inhibitory concentrations (MIC) of 12.5 μg/ml and 12.5–25 μg/ml, respectively. Interestingly, 6 and 8 were also identified as constituents of an extract derived from a healthy plant sample of the host plant U. picroides thereby indicating that the production of bioactive natural products by the endophyte proceeds also under in situ conditions within the host plant.     

Natural occurrence of ampelomyces intracellular mycoparasites in mycelia of powdery mildew fungi

This is the first extensive investigation that quantifies natural mycoparasitic relationships in the phyllosphere. The presence of Ampelomyces spp. was quantified in naturally occurring powdery mildew fungi collected in Hungary and Romania between 1992 and 1995. A total of 570 samples was studied representing 27 species (nine genera) of the Erysiphaceae infecting 41 host plant genera. The incidence of Ampelomyces spp., determined as the proportion of samples in which intracellular pycnidia were present, varied between 4.3 and 68.8% in the host fungal genera studied. The intensity of mycoparasitism, defined as a percentage of the powdery mildew mycelia parasitized by Ampelomyces , ranged from 0.15 to 65%. Both the incidence and the intensity of mycoparasitism showed the lowest values in Blumeria graminis (DC.) Speer collected from wild and cultivated monocotyledons, while the highest values were found in Arthrocladiella mougeotii (Lév.) Vassilkov infecting Lycium halimifolium Mill. plants. The paper reports for the first time the natural occurrence of Ampelomyces in Sawadaea bicornis (Wallr.:Fr.) Homma on maple.     

Biology and biocontrol potential of Ampelomyces mycoparasites, natural antagonists of powdery mildew fungi

Historically, pycnidial fungi belonging to the genus Ampelomyces were among the first mycoparasites to be studied in detail and were also the first fungi used as biocontrol agents of plant parasitic fungi. The interactions between host plants, powdery mildew fungi and Ampelomyces mycoparasites are one of the most evident cases of tritrophic relationships in nature although their study has received little attention in fungal and plant ecology so far. Ampelomyces mycoparasites have now become one of the most advanced in terms of commercial development of a fungal biocontrol agent, although there is still a need for more development work to produce a product with reliability approaching that of conventional chemical treatments. This review summarizes the taxonomy, genetic diversity, life cycle, mode of action, natural occurrence, host range, biocontrol potential, mass production and commercialization of these mycoparasites and compares the biocontrol ability of Ampelomyces with that of other fungal antagonists of powdery mildews.     

一株白粉寄生菌的酚类代谢产物

从得自鼎湖山自然保护区的一株白粉寄生菌(Ampelomyces sp.)SC0307固体发酵物中分离得到7个酚类化合物.通过波谱分析,分别鉴定为2,5-二羟基苯甲醇(1)、对羟基苯甲酸(2)、2,5-二羟基苯甲酸(3)、3,4-二羟基苯甲酸(4)、苯乙酸(5)、3,4-二甲氧基肉桂酸(6)、3,4,5-三甲氧基肉佳酸(7).7个化合物均为从白粉寄生菌属真菌中首次分离获得.