Taxonomic placement of Epichloë poae sp. nov. and horizontal dissemination to seedlings via conidia

Abstract

A new Epichloe species distributed in Africa, Europe, North America and South America on host genera Bromus, Festuca, Lolium and Poa is described. Stromata, characteristic of the genus, frequently occurred on the reproductive tillers of Poa secunda subsp. juncifolia, but neither perithecia nor mature asci were observed. Conidiogenous cells and conidial characteristics were in the range of Epichloe typhina. Regions of the genes encoding β-tubulin (tub2) and translation elongation factor 1-α (tef1) were amplified and sequenced. Phylogenetic analyses of these sequences grouped the Poa secunda subsp. juncifolia endophyte into one group within a non-hybrid Epichloe species complex. On the basis of morphology, host range and evolutionary history we propose that this endophyte represents a new species of Epichloe. The name Epichloe poae is proposed for this endophyte. The infectivity of the conidia produced on plants was evaluated. In the first experiment, using conidia of Epichloe poae from leaves and endophyte-free seeds of Poa secunda subsp. juncifolia we show that when germinating seeds and developing seedlings of the plant were exposed to conidia, 28–57 % of seedlings became infected by the endophyte. The non-inoculated control plants showed no colonization by the endophyte. In the following spring after vernalization, colonized plants on flowering culms produced stromata with conidia. In the second experiment, using stromal conidia and the same procedure, 19–42 % of seedlings of Poa secunda subsp. juncifolia became colonized by the endophyte. Our results demonstrate that Epichloe poae may spread to uninfected grass hosts by conidia frequently formed on the surfaces of plant leaves as well as by conidia formed on stromata.