一株重寄生枝孢菌的基因组测序及重寄生机制分析

Genome sequencing and mycoparasitism mechanism of a Cladosporium sp. strain

摘要:

【背景】枝孢菌SYC63是一株具有重寄生作用和抗菌活性的潜在生防菌株，目前尚无研究报道该菌株的全基因组序列，因此限制了其开发与利用。对该菌株进行基因组测序与分析，将进一步了解其重寄生的分子机制，为其在生物防治上的应用奠定研究基础。【目的】解析枝孢菌SYC63基因组序列信息，初步探究该菌的重寄生作用机制。【方法】利用二代高通量测序平台对枝孢菌SYC63进行全基因组测序，运用相关软件对其测序数据进行基因组组装、基因功能注释、预测次级代谢产物合成基因簇并分析重寄生相关的碳水化合物酶类基因等。【结果】基因组组装后共得到17个contigs，总长度为31 912 211 bp，GC含量为52.80%，预测到12 327个编码基因。其中，4 029、949和6 595个基因分别能在KEGG、COG和GO数据库中被注释到，同时还预测到25个次级代谢产物合成基因簇。对重寄生机制相关的碳水化合物酶类进行分析并与重寄生菌株(拟盘多毛孢菌、木霉及盾壳霉)比较，发现该菌具有较多的糖苷水解酶和糖脂酶基因，而且细胞壁降解酶类基因经锈菌孢子壁处理后在转录组测序中显著上调表达，初步分析了该菌与重寄生木霉在分子水平上的差异及不同于木霉真菌的寄生机制。【结论】从基因组层面解析了枝孢菌的重寄生机制，为深入探究其寄生机制及次生代谢产物的挖掘提供参考信息，对后续开发与利用具有重要意义。

关键词:重寄生;枝孢菌;全基因组;基因功能注释;次级代谢

Abstract:

[Background] Cladosporium sp. SYC63 is a potential biocontrol strain with mycoparasitism and antimicrobial activity. Little is known about the whole genome sequence of this strain, which limits its development and utilization. Genome sequencing and analysis will help us understand the mycoparasitism mechanism of this strain. [Objective] The aim is to analyze the genome sequence of SYC63 and preliminarily explore the mechanism of its mycoparasitism. [Methods] The whole genome of SYC63 was sequenced on the high-throughput sequencing platform, and the genomics tools were employed for sequence assembly, gene prediction and functional annotation, prediction of secondary metabolite synthesis gene clusters, and statistical analysis of carbohydrate-active enzyme genes related to mycoparasitism. [Results] A total of 17 contigs were obtained after genome assembly, with the total length of 31 912 211 bp, the GC content of 52.80%, and 12 327 coding genes. Among them, 4 029, 949 and 6 595 genes were annotated in KEGG, COG and GO databases, respectively. At the same time, 25 gene clusters for secondary metabolite synthesis were predicted. The strain SYC63 had more glycoside hydrolase and glycolipase genes than other mycoparasitic strains (Pestalotiopsis sp., Trichoderma sp. and Coniothyrium minitans). After treatment of the spore wall with rust fungus, the expression of cell wall-degrading enzyme genes was significantly up-regulated, which revealed that the mycoparasitism mechanism of SYC63 was different from that of Trichoderma. [Conclusion] We explored the mycoparasitism mechanism of Cladosporium at the genome level, providing reference information for further studying the mycoparasitism mechanism and mining the secondary metabolites, which is of great significance for the subsequent development and utilization of Cladosporium.

Key words:mycoparasitism;Cladosporium sp.;whole genome;gene function annotation;secondary metabolism