Institute of Botany, University of Basel, Hebelstrasse 1, CH-4056 Basel, Switzerland.
Mol Phylogenet Evol. 2010 May;55(2):599-610. doi: 10.1016/j.ympev.2010.02.013. Epub 2010 Feb 19.
The large subunit of the mitochondrial ribosomal RNA genes (mtLSU) has previously been identified as a highly sensitive molecular marker for intraspecies diversity in the arbuscular mycorrhizal fungus Glomus intraradices. In this study, the respective region was analyzed in five species of Glomus (G. mosseae, G. geosporum, G. caledonium, G. clarum, G. coronatum) from the same major clade (Glomus group A), Glomus sp. ISCB 34 from the related Glomus group B and two species of Scutellospora. Results show low level of genetic polymorphism between related morphospecies. Introns homologous to those found in G. intraradices were detected as well as new ones, some of them containing putative ORFs for homing endonucleases (HEs). Introns without ORFs for HEs seem to have been inherited strictly vertically from the ancestors of Glomus groups A and B while other introns indicate occasional horizontal transfer and possibly maintenance, degeneration and loss together with their associated HE ORFs. Overall, we provide first insights into the evolutionary dynamics of introns and HEs in this ecologically important group of fungi, which was previously not analyzed in this respect.
线粒体核糖体 RNA 基因大亚基（mtLSU）以前被确定为丛枝菌根真菌内球囊霉种内多样性的高度敏感分子标记。在这项研究中，分析了来自同一主要分支（Glomus 组 A）的 5 种 Glomus（G. mosseae、G. geosporum、G. caledonium、G. clarum、G. coronatum）、相关 Glomus 组 B 的 Glomus sp. ISCB 34 以及 2 种 Scutellospora 中的相应区域。结果表明，相关形态种之间遗传多态性水平较低。检测到与内球囊霉中发现的同源内含子，以及新的内含子，其中一些包含归巢内切酶（HEs）的假定 ORFs。没有 HEs 的 ORFs 的内含子似乎是从 Glomus 组 A 和 B 的祖先那里严格垂直遗传下来的，而其他内含子则表明偶尔会发生水平转移，并可能与它们相关的 HE ORFs 一起维持、退化和丢失。总的来说，我们首次深入了解了这个在生态学上很重要的真菌群中内含子和 HEs 的进化动态，以前在这方面没有进行过分析。
