"Mating, Pheromone-signalling pathway and genetic exchange in arbuscular mycorrhizal fungi"

丛枝菌根真菌（AMF）是一种常见的土壤真菌，是根栖共生生物。AMF与大约80%的维管植物的根形成共生。这些真菌提供了各种服务，特别是提高了磷吸收和耐旱能力。从遗传学的角度来看，AMF与大多数其他真核生物相比非常复杂。AMF是多核生物，在其整个生命周期中含有数千个细胞核。有很多证据表明，这些细胞核是遗传上不同的，真菌分离株表现出广泛的细胞内遗传多态性。因此，许多与AMF生物学相关的基本问题仍然难以研究。丛枝菌根真菌被认为是通过大的多核孢子繁殖的无性生物。AMF上从未观察到有性生殖。这项研究计划的目的是调查AMF是否有性行为。本工作利用高通量基因组学方法研究了四个具体目标：（1）描述球囊霉属（Glomus）物种的信息素信号通路;（2）研究球囊霉属（Glomus）物种性位点的基因组结构，并比较球囊霉属（Glomus）物种与毛霉目（Mucorales）和微孢子虫属（Microsporidia）物种性位点的基因同线性;（3）利用毛霉亚门（Mucoromycotina）分泌的信息素三孢酸诱导不规则球囊霉（Glomus irregulare）的有性繁殖，（4）通过杂交实验和线粒体DNA标记的基因分型，研究不同基因型AMF分离株间的基因交换。

Arbuscular mycorrhizal fungi (AMF) are root-inhabiting symbionts organisms, and among the most common soil fungi. AMF form symbioses with the roots of approximately 80% of all vascular plant species. These fungi offer a variety of services, in particular, improved capacity for P uptake and drought tolerance. From a genetic point of view, AMF are extremely complex when compared to most other eukaryotes. AMF are coenocytic organisms that contain thousands of nuclei throughout their life cycle. There is much evidence that these nuclei are genetically divergent, and fungal isolates show extensive intracellular genetic polymorphism. Therefore, many fundamental questions bearing on AMF biology remain difficult to investigate. Arbuscular mycorrhizal fungi are presumed to be asexual organisms that are reproducing via large multinucleated spores. Sexual reproduction has never been observed on AMF. The goal of this research program is to investigate if AMF do have sex. This work exploits high-throughput genomic approaches to investigate four specific objectives: (1) to characterize pheromone-signalling pathway in Glomus species; (2) to study the genomic structure of the Glomus species sex locus and to compare the gene synteny of Glomus sex locus to Mucorales and Microsporidia species; (3) to induce sexual reproduction between several Glomus irregulare isolates using trisporic acids, a pheromone commonly secreted by Mucoromycotina, and to track gene expression of some key genes using quantitative PCR; (4) to study gene exchange between genetically different AMF isolates by using crossing experiments and subsequent genotyping with mitochondrial DNA markers.