Citation:
Abstract:
Powdery mildews on oaks, caused by Erysiphe species, have serious ecological consequences on a range of Quercus hosts. In addition to Erysiphe quercicola, E. alphitoides is one of the most common and widespread species of Erysiphe having a wide host range among oak species, and a clear economic significance in applied ecology, forestry, and forest pathology. There are many publications addressing these important tree pathogens. Previous phylogenetic examinations have shown that E. alphitoides refers to a complicated species assemblage with insufficient taxonomic resolution in ITS + 28S analyses; the associated sequences form an insufficiently resolved species complex. The majority of species within the E. alphitoides complex cannot be unequivocally identified based solely on ITS + 28S analyses. Most of the additional species of the E. alphitoides complex are distributed in Asia, with a concentration in Japan. The question posed is whether there is a single widespread powdery mildew species, E. alphitoides, or an assemblage of closely allied species. To answer this question, specimens of related recognized species, particularly those from Japan, have been subjected to phylogenetic multilocus examinations, including CAM, GAPDH, GS, ITS + 28S, RPB2, and TUB sequences. An analysis of the concatenated sequences resulted in the confirmation of several distinct species. These species form highly supported clades that include E. alphitoides, E. aucubae, E. euonymicola, E. ipomoeae, E. menispermi var. dahurica, E. orixae, E. pseudolonicerae, E. sinomenii and E. wallrothii. Erysiphe akebiae as well as the relationship between Japanese and North American collections requires further examinations.