<i>Cercospora hokkaidensis</i>: A Novel Species Associated with Leaf Spot in Sugar Beet (<i>Beta vulgaris</i>) in Hokkaido, Japan

Cercospora leaf spot (CLS), caused by Cercospora beticola, is a devastating foliar disease of sugar beet (Beta vulgaris) that imposes a major constraint on yields worldwide. Various Cercospora species have recently been reported on sugar beet associated with CLS globally. The diversity of Cercospora species on CLS that occurred in Hokkaido, Japan, was examined based on the phylogenetic analyses in this study. These isolates of Cercospora species were divided into three groups based on multi-loci molecular phylogenetic analyses with a combined matrix of DNA sequences composed of rDNA ITS, actin, calmodulin, histone, and translation elongation factor. In addition, the ATP binding cassette transporter (ATR) gene sequences were newly introduced for multi-loci phylogenetic analyses as an alternative locus. Japanese Cercospora isolates from B. vulgaris formed well-supported clades by bootstrap values, which were recognized as C. beticola, C. cf. resedae, and an unknown lineage of Cercospora species. From these results, Cercospora hokkaidensis, isolated from sugar beet in three locations across Hokkaido, was described in this study. Moreover, ATR was proposed as a new candidate species barcoding region to recognize Cercospora species.