The genome of Laccaria bicolor provides insights into mycorrhizal symbiosis
The genome of Laccaria bicolor provides insights into mycorrhizal symbiosis
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DOI：
10.1038/nature06556
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发表时间：
2008-03-06
期刊：
影响因子：
64.8
通讯作者：
Grigoriev, I. V.
中科院分区：
文献类型：
--
作者：
Martin, F.;Aerts, A.;Grigoriev, I. V.
菌根共生-根和土壤真菌的联盟-在陆地生态系统中是普遍存在的，并且可能是植物在陆地上定居的基础（1，2）。北方、温带和山地森林都依赖于外生真菌（1）。因此，确定调节共生发展和代谢活动的主要因素将为了解外生真菌在植物发育和生理学中的作用打开大门，从而探索这种共生的全部生态意义。在这里，我们报告的基因组序列的外生菌根菌Laccariabicolor（图1）和突出的基因集参与根际定植和共生。这个65兆碱基的基因组集合包含20,000个预测的蛋白质编码基因和非常大量的转座子和重复序列。我们检测到了意想不到的基因组特征，最值得注意的是一系列功能未知的效应子型小分泌蛋白（SSP），其中几种仅在共生组织中表达。最高表达的SSP积累在增殖菌丝定殖宿主根。外生真菌特异性的SSP可能在共生关系的建立中起决定性作用.意想不到的观察，L。bicolor缺乏参与降解植物细胞壁的碳水化合物活性酶，但保持降解非植物细胞壁多糖的能力，揭示了菌根真菌的双重腐养和活体营养生活方式，使其能够在土壤和活植物根部生长。预测的L。因此，双色基因组指出了以前未知的在活体营养型菌根真菌中运作的共生机制。该基因组的可用性提供了一个无与伦比的机会，以更深入地了解共生体与其生态系统中的植物相互作用的过程，以在碳和氮循环中发挥重要作用，这对可持续的植物生产力至关重要。
Mycorrhizal symbioses - the union of roots and soil fungi - are universal in terrestrial ecosystems and may have been fundamental to land colonization by plants(1,2). Boreal, temperate and montane forests all depend on ectomycorrhizae(1). Identification of the primary factors that regulate symbiotic development and metabolic activity will therefore open the door to understanding the role of ectomycorrhizae in plant development and physiology, allowing the full ecological significance of this symbiosis to be explored. Here we report the genome sequence of the ectomycorrhizal basidiomycete Laccaria bicolor ( Fig. 1) and highlight gene sets involved in rhizosphere colonization and symbiosis. This 65- megabase genome assembly contains 20,000 predicted protein- encoding genes and a very large number of transposons and repeated sequences. We detected unexpected genomic features, most notably a battery of effector- type small secreted proteins ( SSPs) with unknown function, several of which are only expressed in symbiotic tissues. The most highly expressed SSP accumulates in the proliferating hyphae colonizing the host root. The ectomycorrhizae- specific SSPs probably have a decisive role in the establishment of the symbiosis. The unexpected observation that the genome of L. bicolor lacks carbohydrate- active enzymes involved in degradation of plant cell walls, but maintains the ability to degrade non- plant cell wall polysaccharides, reveals the dual saprotrophic and biotrophic lifestyle of the mycorrhizal fungus that enables it to grow within both soil and living plant roots. The predicted gene inventory of the L. bicolor genome, therefore, points to previously unknown mechanisms of symbiosis operating in biotrophic mycorrhizal fungi. The availability of this genome provides an unparalleled opportunity to develop a deeper understanding of the processes by which symbionts interact with plants within their ecosystem to perform vital functions in the carbon and nitrogen cycles that are fundamental to sustainable plant productivity.