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

丛枝菌根真菌(AMF)是根际共生生物，也是最常见的土壤真菌之一。AMF与大约80%的维管植物物种的根形成共生。这些真菌提供各种服务，特别是提高了磷吸收和耐旱性的能力。从遗传学的角度来看，AMF与大多数其他真核生物相比是极其复杂的。AMF是一种共核生物，在其整个生命周期中含有数千个核。有许多证据表明，这些细胞核在遗传上是不同的，真菌分离株表现出广泛的细胞内遗传多态。因此，许多与AMF生物学有关的基本问题仍然很难研究。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。在AMF上从未观察到有性繁殖。这个研究项目的目标是调查AMF是否有性行为。这项工作利用高通量基因组学方法来研究四个特定的目标：(1)表征球菌属物种的信息素信号通路；(2)研究球菌属物种性基因座的基因组结构，并将球菌性基因座与毛霉目和微孢子虫物种的基因同源性进行比较；(3)利用三孢子酸(毛霉菌普遍分泌的信息素)诱导几个不规则球菌分离物之间的有性繁殖，并使用定量PCR技术跟踪一些关键基因的基因表达；(4)通过交叉实验和随后的线粒体DNA标记的基因分型来研究遗传上不同的AMF分离物之间的基因交换。

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.