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Updated: Aug 17, 2026
Purification of High Molecular Weight Genomic DNA from Powdery Mildew for Long-Read Sequencing
Published on: March 31, 2017
Ampelomyces mycoparasites from apple powdery mildew identified as a distinct group based on single-stranded
Orsolya Szentiványi1, Levente Kiss, John C Russell
1Plant Protection Institute of the Hungarian Academy of Sciences, PO Box 102, H-1525 Budapest, Hungary.
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.
Insights
This study reveals distinct genetic groups within Ampelomyces fungi, common antagonists of powdery mildew. Isolates from apple powdery mildew (Podosphaera leucotricha) form a unique group, differing from those found on other mildews.
Area of Science:
- Mycology
- Plant Pathology
- Fungal Genetics
Background:
- Ampelomyces fungi are crucial natural antagonists of powdery mildews globally.
- Understanding the genetic diversity of Ampelomyces is key to their role in biological control.
- Previous studies have suggested potential taxonomic ambiguity in certain Ampelomyces isolates.
Purpose of the Study:
- To investigate the genetic diversity of Ampelomyces isolates from various powdery mildew hosts, including apple powdery mildew (Podosphaera leucotricha).
- To differentiate between true Ampelomyces species and other fungi based on genetic markers.
- To explore potential host-specific adaptations or variations within Ampelomyces populations.
Main Methods:
- Isolation of 52 new Ampelomyces isolates from P. leucotricha and 13 from other Erysiphaceae species across four European countries.
- Genetic diversity screening using single-stranded conformation polymorphism (SSCP) analysis of the internal transcribed spacer (ITS) region of ribosomal DNA (rDNA).
- Phylogenetic analysis of ITS sequences to confirm SSCP findings and assess evolutionary relationships.
Main Results:
- Eight distinct genetic groups were identified among the Ampelomyces isolates based on ITS-SSCP patterns.
- Faster-growing isolates, previously misidentified as Ampelomyces, were genetically distinct and did not belong to the Ampelomyces genus.
- Isolates obtained from apple powdery mildew (P. leucotricha) formed a genetically homogeneous and distinct group, separate from other Ampelomyces isolates.
Conclusions:
- The study clarifies the genetic diversity within the Ampelomyces genus, distinguishing true antagonists from other fungi.
- Ampelomyces mycoparasites associated with apple powdery mildew represent a genetically distinct population.
- Temporal asynchrony in the life cycles of apple powdery mildew and other mildews may contribute to the genetic divergence observed in their respective Ampelomyces antagonists.
