Genomic Organization and Mechanisms of Inheritance in Arbuscular Mycorrhizal Fungi: Contrasting the Evidence and Implications of Current Theories

摘要: Most plants, including the majority of crop species, associate with a specific group soil fungi called arbuscular mycorrhizal (AM) fungi. These facilitate uptake plant resources and are increasingly acknowledged as being critical to ecosystem function. This high level ecological success is not expected for species that reproduce asexually, they be vulnerable accumulation deleterious mutations (Muller 1932; Kondrashov 1988) pathogenesis (Hamilton 1980; Lively 1987). Rather, AM have flourished since origin plants (Pirozynski Malloch 1975; Redecker et al. 2000), appear oldest asexual multicellular eukaryotes. While importance evolutionary novelty these become clear, basic genetics remain enigmatic. In fact, their genetic structure seems unusual in two ways. Firstly, individual cells always contain many nuclei, into thousands or tens thousands. And secondly, also very levels variation, 13 variants at what would single copy regions genome. It likely presence maintenance this standing variation related long-term persistence species. However, issues such arrangement between, within, nuclei controversial. Two organizational structures been advocated. it possible all intra-cellular present within cell identical, i.e., homokaryotic (Pawlowska Taylor 2004; Pawloska 2005). Alternatively, much may distributed between each containing multiple genomes, heterokaryotic (Bever Morton 1999; Kuhn 2001; Hijri Sanders scenarios different implications our understanding inheritance