Discovery of novel intermediate forms redefines the fungal tree of life
Discovery of novel intermediate forms redefines the fungal tree of life
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DOI：
10.1038/nature09984
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发表时间：
2011-06-09
期刊：
影响因子：
64.8
通讯作者：
Richards, Thomas A.
中科院分区：
文献类型：
--
作者：
Jones, Meredith D. M.;Forn, Irene;Richards, Thomas A.
真菌是陆地生态系统中生物量的主要降解者，并与植物和动物建立重要的相互作用（1 - 3）。然而，我们目前对真菌进化多样性的理解是不完整的（4），并且是基于适合在培养中生长的物种（1）。这些可培养的真菌通常是酵母或丝状形式，由富含几丁质的刚性细胞壁结合。这种身体计划的进化被认为是真菌成功的关键，使它们能够适应异质栖息地并通过营养生活：细胞外消化，然后吸收营养（5）。在这里，我们调查生态学和细胞生物学的一个以前未描述的和高度多样化的真核生物的形式，分支与真菌，使用环境DNA分析结合荧光检测通过DNA探针。这个分支存在于许多生态系统中，包括土壤，淡水和水生沉积物。使用多个核糖体RNA基因的系统发育分析将该分支与Rozella（真菌界的假定主要分支）放在一起（1）。酪胺信号放大结合组特异性荧光原位杂交显示，靶细胞是3 - 5 mm长的小型真核生物，能够形成基于微管的鞭毛。与细胞壁标记物共染色表明，来自进化枝的代表在观察到的任何生命周期阶段都不产生富含几丁质的细胞壁，因此不符合标准的真菌体计划（5）。我们命名这个高度多样化的分支的隐菌门在正式分类的预期。
Fungi are the principal degraders of biomass in terrestrial ecosystems and establish important interactions with plants and animals(1-3). However, our current understanding of fungal evolutionary diversity is incomplete(4) and is based upon species amenable to growth in culture(1). These culturable fungi are typically yeast or filamentous forms, bound by a rigid cell wall rich in chitin. Evolution of this body plan was thought critical for the success of the Fungi, enabling them to adapt to heterogeneous habitats and live by osmotrophy: extracellular digestion followed by nutrient uptake(5). Here we investigate the ecology and cell biology of a previously undescribed and highly diverse form of eukaryotic life that branches with the Fungi, using environmental DNA analyses combined with fluorescent detection via DNA probes. This clade is present in numerous ecosystems including soil, freshwater and aquatic sediments. Phylogenetic analyses using multiple ribosomal RNA genes place this clade with Rozella, the putative primary branch of the fungal kingdom(1). Tyramide signal amplification coupled with group-specific fluorescence in situ hybridization reveals that the target cells are small eukaryotes of 3-5 mm in length, capable of forming a microtubule-based flagellum. Co-staining with cell wall markers demonstrates that representatives from the clade do not produce a chitin-rich cell wall during any of the life cycle stages observed and therefore do not conform to the standard fungal body plan(5). We name this highly diverse clade the cryptomycota in anticipation of formal classification.