Molina M Carmen, DePriest Paula T, Lawrey James D
Departamento de Matemáticas y Física Aplicadas y Ciencias de la Naturaleza, Escuela Superior de Ciencias Experimentales y Tecnología, Universidad Rey Juan Carlos, 28933 Madrid, España.
Mycologia. 2005 Mar-Apr;97(2):454-63. doi: 10.3852/mycologia.97.2.454.
The lichenicolous basidiomycete Marchandiomyces corallinus is widely distributed in North America and Europe, where it commonly is found on a variety of lichens. Theoretically either of these characteristics, a wide geographic range or generalized host ecology, could provide opportunities for genetic differentiation within this species. To determine how genetic variation is partitioned in M. corallinus, 12 fungal isolates were obtained from locations in North America and Europe; at two locations, in Washington County, Maine, and on the Isle of Mull in Scotland, fungi also were isolated from different lichen hosts. Vegetative mycelial compatibility tests were used to determine compatibility groupings from among the isolates; in addition, several PCR amplification products (RAPD, nuITS rDNA) were obtained for each isolate. A number of distinct compatibility groups were recognizable based on geography, not host ecology. In addition compatible isolates always were restricted to either North America or Europe. However RAPD markers indicated that compatible isolates are not always genetically identical. The presence of sequence heterozygosity at specific positions indicated that the isolates are heterokaryotic and a number of distinct haplotypes could be identified based on ITS variation at three separate locations. This type of genetic variation in these fungi suggests that sexual recombination is possible and that genetic differentiation has taken place recently as a result of geographic isolation, not host switching.
地衣共生担子菌珊瑚状马尔钱德氏菌广泛分布于北美和欧洲，通常在多种地衣上被发现。从理论上讲，这两个特征中的任何一个，即广泛的地理分布范围或宽泛的宿主生态，都可能为该物种内的遗传分化提供机会。为了确定珊瑚状马尔钱德氏菌的遗传变异是如何划分的，从北美和欧洲的一些地点获得了12个真菌分离株；在缅因州华盛顿县和苏格兰马尔岛的两个地点，还从不同的地衣宿主中分离出了真菌。利用营养菌丝体相容性试验来确定分离株之间的相容性分组；此外，为每个分离株获得了几种PCR扩增产物（RAPD、核ITS rDNA）。基于地理而非宿主生态，可以识别出一些不同的相容性组。此外，相容的分离株总是局限于北美或欧洲。然而，RAPD标记表明，相容的分离株并不总是基因相同的。特定位置存在序列杂合性表明这些分离株是异核体，并且基于三个不同位置的ITS变异可以识别出一些不同的单倍型。这些真菌中的这种遗传变异类型表明有性重组是可能的，并且由于地理隔离而非宿主转换，最近已经发生了遗传分化。
