丛枝菌根真菌数个种的基因组和转录组研究概况

Genomic and transcriptomic studies of several species of arbuscular mycorrhizal fungi

摘要:

丛枝菌根真菌（AMF）在自然界分布广泛，能与大部分维管植物的根系形成菌根共生体。它们在调节植物群落结构和全球的碳、氮、磷循环等方面发挥着重要的生态功能，也是农林、环境领域最具应用前景的微生物类群。受限于培养方法、研究手段等，长期以来对AMF基因组、转录组特征的认识非常有限。最近10年，AMF基因组和转录组的相关研究在高通量测序技术的推动下取得了较快发展；研究结果也显著提高了对AMF遗传发育、代谢生理、共生机制等的认识。本文综述了目前已完成测序的AMF种类的基因组、转录组信息。结果发现，已测序的AMF种类普遍具有基因组大、转座子丰富、AT碱基含量高、含大量未知功能基因与特异性基因、缺少部分共生相关基因等特点。在转录层面，总结了不同AMF种类、AMF不同共生结构、共生阶段以及与不同寄主植物共生时的转录本特征。结果发现，不同种类AMF的转录本大小差异明显。不同共生阶段或不同共生结构中的AMF转录本也具有较大的差异，且差异表达的基因大部分与养分交易、信号转导等密切相关。相比之下，同种AMF与不同寄主植物共生时的转录本表现出较高的保守性。最后，本文提出了本领域需要重点关注的研究方向，包括AMF纯培养技术的革新、AMF基因功能的解析、非模式AMF类群的研究以及对AMF蛋白组的研究。

关键词:丛枝菌根真菌;球囊菌门;基因组;转录组;共生

Abstract:

Arbuscular mycorrhizal fungi (AMF) are widely distributed in nature and can form mycorrhizal symbiosis with the roots of most vascular plants. They play important ecological roles in the regulation of plant community, and are deeply involved in the global carbon, nitrogen, and phosphorus cycling. They are also the most promising microbial groups in the fields of agriculture, forestry and environment. However, so far the information of their genomic and transcriptomic characters was limited, partially due to the technique limitations in their cultivation. In the past decade, researches on AMF genome and transcriptome have achieved a rapid development under the impetus of high-throughput sequencing. These studies have greatly improved our understanding of AMF in heredity, development, metabolic physiology and symbiosis mechanisms. Here we reviewed the research progresses in the available genomic and transcriptomic information of AMF based on published literature. We found that genomes of available AMF species commonly have large sizes, high transposon abundances, high GC contents, rich in functionally-unknown and species-specific genes, and are lack of some symbiosis-related genes. We also summarized the transcriptomic characteristics of AMF in different symbiotic structures, at different symbiosis stages and with different host plants. The results showed that the transcriptomic sizes generally varied among different AMF species. Also, in different symbiotic structures or at different symbiotic stages, diverse transcriptomic characteristics were found, especially for the expression profiles of genes related to nutrient exchange and signal transduction. In contrast, the transcripts of the same AMF in symbiosis with different host plants were relatively conserved. Finally, we proposed the research directions that need to be focused on in this field, including the innovation of AMF asymbiotic culture technology, the analysis of AMF gene functions, the study of non-model AMF groups and the study of AMF proteome.

Key words:arbuscular mycorrhizal fungi (AMF);Glomeromycota;genomics;transcriptomics;symbiosis