Enhancing identification accuracy for powdery mildews using previously underexploited DNA loci

Area of Science:

• Mycology
• Plant Pathology
• Molecular Biology

Background:

• Powdery mildews are common fungal plant pathogens that are difficult to identify to species level.
• Current DNA markers like the internal transcribed spacer (ITS) have limitations in accurately identifying all powdery mildew species.
• Citizen science initiatives have provided a valuable resource of diverse powdery mildew samples for research.

Purpose of the Study:

• To evaluate new DNA markers for improved identification and phylogenetic reconstruction of powdery mildew species.
• To develop and optimize protocols for amplifying and sequencing candidate genes in powdery mildews.
• To identify the most effective DNA marker for differentiating closely related powdery mildew species.

Main Methods:

• Reviewed existing fungal DNA markers for species-level discrimination.
• Developed amplification and sequencing protocols for seven candidate genes: actin, β-tubulin, calmodulin, Chs, elongation factor 1-α (EF1-α), Mcm7, and Tsr1.
• Assessed the utility of each gene, individually and in combination with ITS, for species identification and phylogenetic analysis.

Main Results:

• The internal transcribed spacer (ITS) marker provided clear results for only 75% of powdery mildew samples.
• Seven candidate genes were tested, with varying success in amplification and sequencing.
• The Mcm7 gene demonstrated the highest utility in differentiating closely related powdery mildew species, both alone and with ITS.

Conclusions:

• The Mcm7 gene is proposed as a highly effective marker for powdery mildew diagnostics, complementing the ITS marker.
• This finding can improve the accuracy of fungal identification and phylogenetic studies.
• The Mcm7 marker may also be applicable to other challenging fungal groups.