Reassessment of Paragnomonia (Sydowiellaceae, Diaporthales) and typification of Paragnomonia fragariae, the cause of strawberry root rot and petiole blight.

Paragnomonia fragariae is a plant pathogenic ascomycete causing root rot and petiole blight of perennial strawberry in northern Europe. This paper provides a revised description of Paragnomonia and P. fragariae with lecto- and epitypification based on the species original description, recent collections from four European countries, examination of specimens used in the previous taxonomic studies and phylogenetic analyses of DNA sequences of LSU, ITS/5.8S and tef1-α. This study presents the first report of P. fragariae on cultivated strawberry in Finland and Lithuania. Our study on growth rate showed that P. fragariae is a cold-adapted fungus growing almost equally at 5 °C as at 20 °C and attaining maximal growth at 15 °C. New primers were designed for amplification of ca. 0.8 kb fragment of tef1-α of Sydowiella fenestrans. Additionally, newly generated sequences of tef1-α were obtained for the first time from 21 isolates of seven species belonging to five genera of Sydowiellaceae, including the type species S. fenestrans, therefore considerably contributing to the current knowledge on phylogenetic relationships of this insufficiently studied group of fungi. The phylogenetic analysis has also revealed that the recently described species "S." centaureii is genetically distant from the generic type S. fenestrans and other Sydowiella.