title: Ampelomyces mycoparasites from apple powdery mildew identified as a distinct group based on single-stranded conformation polymorphism analysis of the rDNA ITS region.
abstract: Pycnidial fungi belonging to the genus Ampelomyces are the most common natural antagonists of powdery mildews worldwide. During a study of the interactions between apple powdery mildew (Podosphaera leucotricha) and Ampelomyces mycoparasites, 52 new Ampelomyces isolates were obtained from P. leucotricha and, in addition, 13 new isolates from other species of the Erysiphaceae in four European countries. Their genetic diversity was screened using single-stranded conformation polymorphism (SSCP) analysis of the internal transcribed spacer (ITS) region of the ribosomal DNA (rDNA). For comparison, 24 isolates obtained from genetic resource collections or other sources were included in this study. Based on the ITS-SSCP patterns, the isolates were placed in eight groups. The isolates belonged to two types based on their growth in culture. The faster-growing and the slower-growing isolates were included in different SSCP groups. A phylogenetic analysis of the ITS sequences of representatives of these groups confirmed the results obtained with the SSCP method, and showed that the faster-growing isolates do not belong to Ampelomyces as suggested by earlier studies. All the isolates from P. leucotricha fell into a distinct SSCP group of genetically homogeneous isolates. This suggests that Ampelomyces mycoparasites which occur in apple powdery mildew are slightly different from the other Ampelomyces groups which contain mycoparasites from various powdery mildew species. This may be because the main growth period of Ampelomyces mycoparasites in apple powdery mildew is isolated in time from that of Ampelomyces isolates that occur in other species of the Erysiphaceae. P. leucotricha starts its life-cycle early in the season, usually in March-April, while most powdery mildews are active in the same environments only late in the year.
authors.affiliation: Plant Protection Institute of the Hungarian Academy of Sciences, PO Box 102, H-1525 Budapest, Hungary.
authors.forename: Orsolya
authors.initials: O
authors.lastname: Szentiványi
authors.forename: Levente
authors.initials: L
authors.lastname: Kiss
authors.forename: John C
authors.initials: JC
authors.lastname: Russell
authors.forename: Gábor M
authors.initials: GM
authors.lastname: Kovács
authors.forename: Krisztina
authors.initials: K
authors.lastname: Varga
authors.forename: Tünde
authors.initials: T
authors.lastname: Jankovics
authors.forename: Silke
authors.initials: S
authors.lastname: Lesemann
authors.forename: Xiang-Ming
authors.initials: XM
authors.lastname: Xu
authors.forename: Peter
authors.initials: P
authors.lastname: Jeffries
mesh_terms: D001203:Ascomycota / Q000145:classification* / Q000235:genetics; D004271:DNA, Fungal / Q000032:analysis / Q000235:genetics; D004275:DNA, Ribosomal / Q000032:analysis*; D027845:Malus / Q000382:microbiology*; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology; D018807:Polymorphism, Single-Stranded Conformational
chemical_list: D004271:DNA, Fungal; D004275:DNA, Ribosomal