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Updated: Aug 7, 2026
Purification of High Molecular Weight Genomic DNA from Powdery Mildew for Long-Read Sequencing
Published on: March 31, 2017
Morphological and phylogenetic comparisons amongst powdery mildews on Catalpa in the UK
Roger T A Cook1, Béatrice Henricot, Alick Henrici
130 Galtres Avenue, York YO31 1JT, UK. rtacook@hotmail.com
Abstract:
Three species of powdery mildew, Erysiphe elevata, E. catalpae, and Neoerysiphe galeopsidis were identified on Catalpa species in England in 2004. A new disease record, N. galeopsidis was the first Catalpa mildew to appear (in June), but it was later out-competed by E. elevata that caused the most serious damage. Both mildews also attacked C. speciosa, C. xerubescens and a new host, xChitalpa tashkentensis, a Chilopsis xCatalpa hybrid. No powdery mildew was detected on C. bungei, C. ovata, or C. fargesii. Identifications of the pathogens using morphological data were fully supported by DNA analysis yielding characteristic rDNA ITS sequences. The sequences placed E. catalpae within the E. aquilegiae clade. The sequences for E. elevata from southern England and France closely matched those from Hungary and North America, confirming the recent spread of this pathogen from the USA. It eventually overran N. galeopsidis and its sudden appearance in the UK could be due to greater aggressiveness and to the production of more ascomata especially during autumns with delayed leaf fall as in 2001. A further species, Oidium hiratae (i.e. Podosphaera sp.), though described from a 1978 UK collection on C. bignonioides, was not detected in the field.
Insights
Powdery mildew species Erysiphe elevata and Neoerysiphe galeopsidis were identified on Catalpa in England. Erysiphe elevata caused the most damage and appears to have spread from North America.
Area of Science:
- Plant pathology
- Mycology
- Horticulture
Background:
- Powdery mildew fungi are significant pathogens of various plant species.
- Catalpa trees are susceptible to several powdery mildew infections, impacting their health and aesthetics.
- Accurate identification and understanding of pathogen spread are crucial for disease management.
Purpose of the Study:
- To identify and characterize powdery mildew species affecting Catalpa in England.
- To determine the host range and genetic relationships of these pathogens.
- To investigate the potential origin and spread of invasive powdery mildew species.
Main Methods:
- Field surveys for disease identification on Catalpa species.
- Morphological analysis of fungal structures.
- DNA sequencing of ribosomal DNA (rDNA) internal transcribed spacer (ITS) regions.
- Phylogenetic analysis to determine pathogen relationships.
Main Results:
- Three powdery mildew species were identified: Erysiphe elevata, E. catalpae, and Neoerysiphe galeopsidis.
- Erysiphe elevata was the dominant and most damaging species, with genetic data suggesting recent introduction from North America.
- Neoerysiphe galeopsidis was a new record for Catalpa in the UK but was outcompeted by E. elevata.
- xChitalpa tashkentensis was identified as a new host for these mildews.
- Certain Catalpa species (C. bungei, C. ovata, C. fargesii) showed no signs of infection.
Conclusions:
- Erysiphe elevata poses a significant threat to Catalpa species in the UK due to its aggressiveness and potential for rapid spread.
- The study highlights the importance of molecular techniques for accurate pathogen identification and tracing disease origins.
- Understanding the dynamics between different powdery mildew species is essential for effective disease control strategies in ornamental trees.
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