Correspondence between genet diversity and spatial distribution of above- and below-ground populations of the ectomycorrhizal fungus Hebeloma cylindrosporum
Correspondence between genet diversity and spatial distribution of above- and below-ground populations of the ectomycorrhizal fungus Hebeloma cylindrosporum
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DOI：
10.1046/j.1365-294x.2001.01265.x
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发表时间：
2001-05-01
影响因子：
4.9
通讯作者：
Marmeisse, R
中科院分区：
文献类型：
--
作者：
Guidot, A;Debaud, JC;Marmeisse, R
外生菌根真菌种群研究主要依赖于子实体（生殖器官）取样。仅对子实体的分析假设它们反映了所有地下基因（菌根和外基质菌丝体）的存在和空间组织。调查了法国西南部4个松树林中的担子菌黑木耳（Hebeloma cylindrosporum）子实体与外生菌根之间的关系。基因鉴定是基于聚合酶链反应（PCR）扩增的核糖体基因间间隔区的高变片段内的多态性比较，使用H。柱孢菌种特异性引物。从子实体斑块或子实体斑块下采集的土壤样品中分选菌根，在菌根采集前几年观察到或未观察到子实体。在子实体下收集的1026个菌根中，平均65%由H. cylindrosporum，而在没有子实体的地方收集的954个中只有2%由该种形成。地上鉴定的所有基因型也在地下鉴定。在斑块中，一个基因型形成的所有或超过90%的子实体，相同的基因型形成的所有或大部分的菌根。在几个不同的结果基因型占据补丁，额外的非结果的可能存在于根系。在所有的情况下，一个基因型的菌根被发现不超过10 - 20厘米的距离，其对应的子实体，并在一个给定的地方消失与相应的菌根消失在1年内。虽然存在于地下的基株总数与形成子实体的基株总数之间并不完全一致，但H. cylindrosporum似乎反映了其地下种群的遗传多样性和空间结构。所获得的结果也说明了快速周转的外生菌根真菌物种的根系在没有任何明显的重大干扰的生态系统。
Population studies of ectomycorrhizal fungal species have largely relied upon fruit body (the reproductive organ) sampling. Analysis of the fruit bodies alone supposes that they reflect the present and spatial organization of all below-ground genets (mycorrhizas and extramatrical mycelia). The relation between fruit bodies and ectomycorrhizas was investigated for the basidiomycete agaric Hebeloma cylindrosporum in four Pinus pinaster stands in south-west France. Genet identification was based on the comparison of polymorphisms within a hypervariable segment of the ribosomal intergenic spacer amplified by polymerase chain reaction (PCR) using a H. cylindrosporum species-specific primer. Mycorrhizas were sorted from soil samples collected underneath patches of fruit bodies or patches where fruit bodies had or had not been observed during the years prior to mycorrhiza collection. On average 65% of the 1026 mycorrhizas collected underneath fruit bodies were formed by H. cylindrosporum, whereas only 2% of the 954 collected in places from where fruit bodies were absent were formed by this species. All genotypes identified above ground were also identified below ground. In patches where one genotype formed all or more than 90% of the fruit bodies, the same genotype formed all or a large majority of the mycorrhizas. In patches occupied by several different fruiting genotypes, additional nonfruiting ones could be present on the root systems. In all cases, the mycorrhizas of one genotype were found no more than 10-20 cm away from its corresponding fruit bodies, and fruit body disappearance at a given place was associated with the disappearance of the corresponding mycorrhizas within 1 year. Although there was not a strict coincidence between the total numbers of genets present below ground and of those forming fruit bodies, fruit body analysis for H. cylindrosporum appears to reflect both the genetic diversity and the spatial structure of its below-ground populations. The results obtained also illustrate the rapid turnover of ectomycorrhizal fungal species on the root systems in the absence of any obvious major disturbance of the ecosystem.