Re-classification of the causal agent of white grain disorder on wheat as three separate species of Eutiarosporella

Abstract

In the late 1990s, a novel Botryosphaeria-like fungal pathogen was observed causing a disease on wheat in Queensland, characterised as white grain disorder (WGD). In recent years, this disease has sporadically appeared across the eastern states of Australia. In this study, internal transcribed spacer (ITS) region sequences were used to compare these fungi to other Botryosphaeriaceae spp. to show that they should be reclassified as members of the Eutiarosporella genus. Using a small population of WGD isolates, we built a three-loci maximum likelihood tree, using ITS, β-tubulin, and Elongation Factor1-α sequences to show that there are three separate Eutiarosporella spp. found in infected grain. This multigene tree, with the support of phenotypic differences between clades observed in vitro, show that that the causal agents of WGD should be delimited into three divergent species; Eutiarosporella tritici-australis, Eutiarosporella darliae, and Eutiarosporella pseudodarliae.