Mycorrhizal Specificity and Function in Myco-heterotrophic Plants
Mycorrhizal Specificity and Function in Myco-heterotrophic Plants
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DOI：
10.1007/978-3-540-38364-2_15
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
D. Taylor;T. Bruns;J. Leake;D. Read
中科院分区：
文献类型：
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作者：
D. Taylor;T. Bruns;J. Leake;D. Read
我们提出了真菌特异性的分析，在真菌异养兰花和单性。我们认为特异性代表一个连续体，只能使用系统发育数据进行适当评估。一些绿色兰花与广泛的根核菌属物种有亲缘关系，因此表现出很少的特异性，而其他绿色兰花，以及所有被研究的绿叶兰和单性兰，与狭窄的真菌系统发育群有亲缘关系，因此表现出显著的特异性。在一些物种中，这种紧密的特异性已被证明在自然条件下从种子萌发到成年，尽管不一定在体外条件下适用。特异性模式与真菌分布模式和几种真菌异养菌的生境变化有关。然而，对其他异养菌的研究表明，即使在多种真菌与植物共存的情况下，也表达出紧密的特异性。此外，在一种情况下，宿主植物的遗传影响已被证明超过了特异性模式的环境影响。主要寄主跳跃和种内寄主种族的形成促进了几种异养菌的特化进化。一些无绿叶兰花与木材腐烂或寄生真菌有关，但最近的许多研究表明，兰花、单性植物和一种苔类植物与外菌根真菌有关。示踪研究表明，自养外菌根寄主植物可以提供固定碳来滋养由共同真菌伴侣连接的异养菌。重要的悬而未决的问题涉及识别现象，特异性的起源和进化，碳交换的生理学和生态学，以及菌异养体与真菌的相互作用是否与自养体有根本不同的方式。
We present an analysis of fungal specificity in myco-heterotrophic orchids and monotropes. We argue that specificity represents a continuum and can only be properly assessed using phylogenetic data. Several green orchids associate with wide phylogenetic arrays ofRhizoctoniaspecies, and hence show little specificity, while other green orchids, and all studied achlorophyllous orchids and monotropes, associate with narrow phylogenetic groups of fungi, and hence show significant specificity. In several species, this tight specificity has been shown to apply from seed germination through adulthood under natural conditions, though not necessarily under in vitro conditions. Patterns of specificity have been correlated with patterns of fungal distribution and habitat variation in several myco-heterotrophs. However, studies of other myco-heterotrophs have shown that tight specificity is expressed even when diverse fungi co-exist with the plant. Moreover, in one case, genetic influences of the host plant have been shown to outweigh environmental influences over the patterns of specificity. Major host jumps and intraspecific host-race formation have contributed to the evolution of specialisation in several myco-heterotrophs. Some achlorophyllous orchids associate with wood-decay or parasitic fungi, but many recent studies have revealed associations with ecto-mycorrhizal fungi in orchids, monotropes, and a liverwort. Tracer studies show that autotrophic ecto-mycorrhizal host plants can provide the fixed carbon to nourish myco-heterotrophs linked by a shared fungal partner. Important outstanding questions concern recognition phenomena, the origins and evolution of specificity, the physiology and ecology of carbon exchange, and whether myco-heterotrophs interact with fungi in fundamentally different ways than do autotrophs.