Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Private Bag X20, Hatfield 0028, South Africa; Department of Conservation Ecology and Entomology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa.
Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Private Bag X20, Hatfield 0028, South Africa.
Fungal Genet Biol. 2020 Apr;137:103350. doi: 10.1016/j.fgb.2020.103350. Epub 2020 Jan 31.
Teratosphaeria destructans is an aggressive fungal pathogen causing leaf and shoot blight on young Eucalyptus trees in plantations. The disease occurs across tropical and subtropical regions of South East Asia and has recently been found in South Africa. Asexual structures of the pathogen are produced on infected tissues, but sexual structures have never been observed. The aim of this study was to investigate the reproductive biology of T. destructans by characterising its mating type (MAT1) locus and investigating its potential for sexual recombination. We found that T. destructans has a heterothallic mating system, with either the MAT1-1-1 and MAT1-1-10 genes (MAT1-1 idiomorph) or the MAT1-2-1 and MAT1-2-12 genes (MAT1-2 idiomorph) present in a single individual. With a multiplex PCR assay, it was possible to distinguish the two MAT idiomorphs in several Teratosphaeria species and this approach was applied to six global populations of T. destructans. Although both mating types occurred in the South East Asian populations, a single mating type dominated each population. Isolates from the recent disease outbreak in South Africa comprised only a single mating type. Attempts to induce a sexual cycle in vitro using strains of opposite mating type were not successful. The uneven distribution of mating types in populations of T. destructans and the presence of only an asexual state on infected tissues suggests the absence of or at least a minor role for sexual reproduction where the pathogen occurs on non-native Eucalyptus in plantations.
毁灭茎点霉是一种侵袭性真菌病原体，可导致种植园中桉树的叶片和嫩梢枯萎病。该病害发生在东南亚的热带和亚热带地区，最近在南非也有发现。病原体的无性结构在受感染的组织上产生，但从未观察到有性结构。本研究旨在通过描述其交配型（MAT1）基因座并研究其潜在的有性重组能力来研究毁灭茎点霉的生殖生物学。我们发现，毁灭茎点霉具有异宗配合的交配系统，单个个体中存在 MAT1-1-1 和 MAT1-1-10 基因（MAT1-1 同型）或 MAT1-2-1 和 MAT1-2-12 基因（MAT1-2 同型）。通过多重 PCR 检测，可以区分几种 Teratosphaeria 物种中的两种 MAT 同型，并且该方法应用于六个全球毁灭茎点霉种群。尽管两种交配型都存在于东南亚种群中，但每个种群都以单一交配型为主。来自南非最近疾病爆发的分离株仅包含单一的交配型。使用相反交配型的菌株在体外诱导有性循环的尝试并未成功。毁灭茎点霉种群中交配型的不均匀分布以及感染组织上仅存在无性状态表明，在种植园中桉树非原生地发生病害时，有性生殖的缺失或至少作用较小。
