Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra 2601, Australia.
Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra 2601, Australia.
Fungal Genet Biol. 2017 Dec;109:36-45. doi: 10.1016/j.fgb.2017.10.005. Epub 2017 Oct 23.
White grain disorder (WGD) is a recently emerged wheat disease in Australia caused by three Botryosphaeriaceae fungi, from the genus Eutiarosporella. These species are E. tritici-australis, E. darliae, and E. pseudodarliae. Characterisation of the mating type genes for the WGD-species show that the genome sequence of a single E. darliae and E. pseudodarliae isolate both harbour MAT1-2-1 and MAT1-1-1, which suggests that these species are homothallic. However, unlike most other characterised mating-type loci from other homothallic Dothideomycetes, these species' MAT1-1-1 are located at a separate locus, inserted within the coding region of another gene. The sequenced strain of E. tritici-australis analysed did not harbour MAT1-1-1. Including the sequenced strain, we screened the mating type genes present in 16 E. tritici-australis individuals isolated from infected grain from fields in South Australia. Of these 16, 11 harbour MAT1-1-1 and the other five harbour MAT1-2-1. The genome of a MAT1-1-1 harbouring isolate was re-sequenced, which demonstrated that MAT1-1-1 was present at the MAT locus. We examined non-coding DNA surrounding the MAT1-1-1 gene in E. pseudodarliae and observed fragments of the MAT locus both up and downstream. These fragments and their orientation around MAT1-1-1 is similar to characterised heterothallic Botryosphaeriaceae. Based on these gene arrangements, we conclude that the new MAT1-1-1 containing locus likely originated from a cryptic DNA integration event between two heterothallic individuals. We hypothesise that this integration event led to the formation of a homothallic lineage, which is the common ancestor of E. darliae and E. pseudodarliae.
小麦白粒紊乱症（WGD）是澳大利亚一种新出现的小麦病害，由三个属于 Botryosphaeriaceae 真菌的物种引起，分别来自 Eutiarosporella 属。这些物种是 E. tritici-australis、E. darliae 和 E. pseudodarliae。对 WGD 物种的交配型基因进行特征分析表明，单个 E. darliae 和 E. pseudodarliae 分离株的基因组序列都包含 MAT1-2-1 和 MAT1-1-1，这表明这些物种是同宗配合的。然而，与其他同宗配合的 Dothideomycetes 中大多数已确定的交配型基因座不同，这些物种的 MAT1-1-1 位于一个单独的基因座中，插入另一个基因的编码区。分析的 E. tritici-australis 测序菌株不包含 MAT1-1-1。我们对从南澳大利亚受感染谷物田间分离的 16 个 E. tritici-australis 个体的交配型基因进行了筛选，包括测序菌株。在这 16 个个体中，有 11 个含有 MAT1-1-1，其他 5 个含有 MAT1-2-1。含有 MAT1-1-1 的分离株的基因组进行了重新测序，结果表明 MAT1-1-1 存在于 MAT 基因座。我们检查了 E. pseudodarliae 中 MAT1-1-1 基因周围的非编码 DNA，并观察到 MAT 基因座上下游的片段。这些片段及其围绕 MAT1-1-1 的取向与已描述的异宗配合 Botryosphaeriaceae 相似。基于这些基因排列，我们得出结论，包含新的 MAT1-1-1 的基因座可能源自两个异宗配合个体之间的隐性 DNA 整合事件。我们假设，这种整合事件导致了同宗配合谱系的形成，这是 E. darliae 和 E. pseudodarliae 的共同祖先。
