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	Mycorrhizas alter nitrogen acquisition by the terrestrial orchid Cymbidium goeringii
	Wu J. R. ; Ma H. C. ; Xu X. L. ; Qiao N. ; Guo S. T. ; Liu F. ; Zhang D. H. ; Zhou L. P.
	2013
关键词	Mycorrhizal fungi amino acid uptake Cymbidium species nutrient acquisition N-15 labelling catasetum-fimbriatum orchidaceae goodyera-repens growth fungi soil ecosystems phosphorus metabolism symbiosis sedge
英文摘要	Orchid mycorrhizas exhibit a unique type of mycorrhizal symbiosis that occurs between fungi and plants of the family Orchidaceae. In general, the roots of orchids are typically coarse compared with those of other plant species, leading to a considerably low surface area to volume ratio. As a result, orchids are often ill-adapted for direct nutrient acquisition from the soil and so mycorrhizal assocaitions are important. However, the role of the fungal partners in the acquisition of inorganic and organic N by terrestrial orchids has yet to be clarified. Inorganic and amino acid N uptake by non-mycorrhizal and mycorrhizal Cymbidium goeringii seedlings, which were grown in pots in a greenhouse, was investigated using a N-15-labelling technique in which the tracer was injected at two different soil depths, 25 cm or 75 cm. Mycorrhizal C. goeringii seedlings were obtained by inoculation with three different mycorrhizal strains isolated from the roots of wild terrestrial orchids (two C. goeringii and one C. sinense). Non-mycorrhizal C. goeringii primarily took up NO3 from tracers injected at 25-cm soil depth, whereas C. goeringii inoculated with all three mycorrhiza primarily took up NH4 injected at the same depth. Inoculation of the mycorrhizal strain MLX102 (isolated from adult C. sinense) on C. goeringii roots only significantly increased the below-ground biomass of the C. goeringii; however, it enhanced (NH4)-N-15 uptake by C. goeringii at 25-cm soil depth. Compared to the uptake of tracers injected at 25-cm soil depth, the MLX102 fungal strain strongly enhanced glycine-N uptake by C. goeringii from tracers injected at 75-cm soil depth. Cymbidium goeringii inoculated with CLB113 and MLX102 fungal strains demonstrated a similar N uptake pattern to tracers injected at 25-cm soil depth. These findings demonstrate that mycorrhizal fungi are able to switch the primary N source uptake of a terrestrial orchid, in this case C. goeringii, from NO3 to NH4. The reasons for variation in N uptake in the different soil layers may be due to possible differentiation in the mycorrhizal hyphae of the C. goeringii fungal partner.
出处	Annals of Botany
卷	111
期	6
页	1181-1187
收录类别	SCI
语种	英语
ISSN号	0305-7364
内容类型	SCI/SSCI论文
源URL	[http://ir.igsnrr.ac.cn/handle/311030/30155]
专题	地理科学与资源研究所_历年回溯文献
推荐引用方式 GB/T 7714	Wu J. R.,Ma H. C.,Xu X. L.,et al. Mycorrhizas alter nitrogen acquisition by the terrestrial orchid Cymbidium goeringii. 2013.

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