The cacao pathogen Moniliophthora roreri (Marasmiaceae) possesses biallelic A and B mating loci but reproduces clonally
The cacao pathogen Moniliophthora roreri (Marasmiaceae) possesses biallelic A and B mating loci but reproduces clonally
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DOI：
10.1038/hdy.2016.5
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发表时间：
2016-06-01
期刊：
影响因子：
3.8
通讯作者：
Aime, M. C.
中科院分区：
文献类型：
--
作者：
Diaz-Valderrama, J. R.;Aime, M. C.
可可病原菌霉霉属于蘑菇形成科，但从未观察到它产生子实体，这使其有性繁殖的能力受到质疑。在本研究中，我们鉴定了红毛鼠的潜在交配基因A （HD1和HD2）和B（信息素前体和信息素受体）。随后设计了一种基于pcr的方法来确定来自该真菌地理范围内的47个分离株的交配类型。我们开发并生成了11个标记的微卫星集，并进行了关联和连锁不平衡（标准化关联指数，I-A(s)）分析。我们还进行了祖先重建分析，以表明M. roreri的祖先被预测为异thallic和四极体，这与滑动窗口分析一起支持A和B交配位点可能不连接，并遵循基因组内的四极体组织。A基因座由一对HD1和HD2基因组成，而B基因座由一对信息素前体Mr_Ph4和受体STE3_Mr4组成。两个A和B等位基因，但只鉴定出两种交配类型。关联分析将分离物根据交配类型划分为两个明确的遗传上不同的群体；I-A(s)值显示出在无性繁殖中预期的高连锁不平衡。有趣的是，在南美洲的分离株中发现了两种交配类型，但在中美洲的分离株中只发现了一种交配类型，这支持了先前的假设，即在从南美洲引入真菌一次或很少的情况下，在中美洲进行了无性系传播。
The cacao pathogen Moniliophthora roreri belongs to the mushroom-forming family Marasmiaceae, but it has never been observed to produce a fruiting body, which calls to question its capacity for sexual reproduction. In this study, we identified potential A (HD1 and HD2) and B (pheromone precursors and pheromone receptors) mating genes in M. roreri. A PCR-based method was subsequently devised to determine the mating type for a set of 47 isolates from across the geographic range of the fungus. We developed and generated an 11-marker microsatellite set and conducted association and linkage disequilibrium (standardized index of association, I-A(s)) analyses. We also performed an ancestral reconstruction analysis to show that the ancestor of M. roreri is predicted to be heterothallic and tetrapolar, which together with sliding window analyses support that the A and B mating loci are likely unlinked and follow a tetrapolar organization within the genome. The A locus is composed of a pair of HD1 and HD2 genes, whereas the B locus consists of a paired pheromone precursor, Mr_Ph4, and receptor, STE3_Mr4. Two A and B alleles but only two mating types were identified. Association analyses divided isolates into two well-defined genetically distinct groups that correlate with their mating type; I-A(s) values show high linkage disequilibrium as is expected in clonal reproduction. Interestingly, both mating types were found in South American isolates but only one mating type was found in Central American isolates, supporting a prior hypothesis of clonal dissemination throughout Central America after a single or very few introductions of the fungus from South America.