Genome of an arbuscular mycorrhizal fungus provides insight into the oldest plant symbiosis
Genome of an arbuscular mycorrhizal fungus provides insight into the oldest plant symbiosis
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DOI：
10.1073/pnas.1313452110
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发表时间：
2013-12-10
影响因子：
11.1
通讯作者：
Martin, Francis
中科院分区：
文献类型：
--
作者：
Tisserant, Emilie;Malbreil, Mathilde;Martin, Francis
在中古生时期，一个独特的早期分支真菌门--球囊菌门（Glomeromycota）的互惠共生关系被广泛认为促进了陆生植物的进化。这些丛枝菌根真菌（AMF）在磷循环中发挥着重要作用，这对可持续的作物生产力至关重要。AMF不同寻常的生物学特征长期以来一直吸引着进化生物学家。多核菌丝由数百个核组成，并通过多核孢子进行克隆繁殖。有人认为AMF在生命周期中保持几个不同基因组的稳定组合，但这种基因组组织受到质疑。在这里，我们介绍了153-Mb的不规则Rhizophagus单倍体基因组和它的28，232个基因库。所观察到的低水平的基因组多态性（0.43 SNP/kb）与多个高度分化的基因组的发生不一致。交配相关基因的扩增表明了隐性性别相关过程的存在。基因分类的比较证实了R. irregularis与Mucoromycotina相近。AMF专性生物营养不能用基因组侵蚀或任何相关的代谢复杂性损失来解释，但其特征是缺乏编码植物细胞壁降解酶的基因和参与毒素和硫胺素合成的基因。一组菌根诱导的分泌蛋白在共生组织中表达。目前的全面剧目的R。irregularis基因的研究为进一步研究球囊菌门内共生相关机制提供了基础。
The mutualistic symbiosis involving Glomeromycota, a distinctive phylum of early diverging Fungi, is widely hypothesized to have promoted the evolution of land plants during the middle Paleozoic. These arbuscular mycorrhizal fungi (AMF) perform vital functions in the phosphorus cycle that are fundamental to sustainable crop plant productivity. The unusual biological features of AMF have long fascinated evolutionary biologists. The coenocytic hyphae host a community of hundreds of nuclei and reproduce clonally through large multinucleated spores. It has been suggested that the AMF maintain a stable assemblage of several different genomes during the life cycle, but this genomic organization has been questioned. Here we introduce the 153-Mb haploid genome of Rhizophagus irregularis and its repertoire of 28,232 genes. The observed low level of genome polymorphism (0.43 SNP per kb) is not consistent with the occurrence of multiple, highly diverged genomes. The expansion of mating-related genes suggests the existence of cryptic sex-related processes. A comparison of gene categories confirms that R. irregularis is close to the Mucoromycotina. The AMF obligate biotrophy is not explained by genome erosion or any related loss of metabolic complexity in central metabolism, but is marked by a lack of genes encoding plant cell wall-degrading enzymes and of genes involved in toxin and thiamine synthesis. A battery of mycorrhiza-induced secreted proteins is expressed in symbiotic tissues. The present comprehensive repertoire of R. irregularis genes provides a basis for future research on symbiosis-related mechanisms in Glomeromycota.