Identification of the pathogen Podosphaera erigerontis-canadensis causing powdery mildew disease on dandelion (Taraxacum officinale) in US Arkansas state

Powdery mildew was observed on common dandelion (Taraxacum officinale), collected in Fayetteville, AR, USA, and was identified using morphology and DNA sequences of ITS and 28S ribosomal RNA (rRNA) gene regions. Four primer pairs were used in this study: (1) the powdery mildew specific primer pair PMITS1/2 produced a 696 bp DNA fragment including full sequence of 563 bp DNA fragment amplified by ITS1/4 (KU563734); (2) CTW13/TW14 created a 279 bp DNA fragment including partial sequence of 28S rRNA gene (KU563735); (3) the 28S rRNA region primer pair NL1f/TW14 amplified a 899 bp DNA fragment (KX610821); and (4) the primer pair ITS1/4 amplified a 563 bp DNA fragment including partial sequence of 18S ribosomal RNA gene and complete sequence of ITS1, the 5.8S rRNA gene, ITS2, and partial sequence of the 28S rRNA gene. The similarity analysis by Blast and phylogenetic analysis indicated that the powdery mildew pathogen in dandelion collected from Arkansas was Podosphaera erigerontis-canadensis.