Smith Alistair J H, Potvin Lynette R, Lilleskov Erik A
Michigan Technological University, 1400 Townsend Dr, Houghton, MI, 49931, USA.
Northern Research Station, US Forest Service, 410 MacInnes Drive, Houghton, MI, 49931-1199, USA.
Mycorrhiza. 2015 Nov;25(8):649-62. doi: 10.1007/s00572-015-0640-9. Epub 2015 Apr 24.
Ectomycorrhizal fungi (EcMF) typically colonize nursery seedlings, but nutritional and growth effects of these communities are only partly understood. To examine these effects, Picea glauca seedlings collected from a tree nursery naturally colonized by three dominant EcMF were divided between fertilized and unfertilized treatments. After one growing season seedlings were harvested, ectomycorrhizas identified using DNA sequencing, and seedlings analyzed for leaf nutrient concentration and content, and biomass parameters. EcMF community structure-nutrient interactions were tested using nonmetric multidimensional scaling (NMDS) combined with vector analysis of foliar nutrients and biomass. We identified three dominant species: Amphinema sp., Atheliaceae sp., and Thelephora terrestris. NMDS + envfit revealed significant community effects on seedling nutrition that differed with fertilization treatment. PERMANOVA and regression analyses uncovered significant species effects on host nutrient concentration, content, and stoichiometry. Amphinema sp. had a significant positive effect on phosphorus (P), calcium and zinc concentration, and P content; in contrast, T. terrestris had a negative effect on P concentration. In the unfertilized treatment, percent abundance of the Amphinema sp. negatively affected foliar nitrogen (N) concentration but not content, and reduced foliar N/P. In fertilized seedlings, Amphinema sp. was positively related to foliar concentrations of N, magnesium, and boron, and both concentration and content of manganese, and Atheliaceae sp. had a negative relationship with P content. Findings shed light on the community and species effects on seedling condition, revealing clear functional differences among dominants. The approach used should be scalable to explore function in more complex communities composed of unculturable EcMF.
外生菌根真菌（EcMF）通常会定殖在苗圃幼苗上，但人们对这些群落的营养和生长影响仅了解一部分。为了研究这些影响，将从一个自然定殖有三种优势外生菌根真菌的苗圃采集的白云杉幼苗分为施肥和未施肥处理组。经过一个生长季节后，收获幼苗，通过DNA测序鉴定外生菌根，并分析幼苗的叶片养分浓度、含量和生物量参数。使用非度量多维标度法（NMDS）结合叶片养分和生物量的向量分析来测试外生菌根真菌群落结构与养分的相互作用。我们鉴定出三种优势物种：Amphinema属物种、 Atheliaceae属物种和土生棱柄盘菌。NMDS + envfit分析表明，群落对幼苗营养有显著影响，且这种影响因施肥处理而异。PERMANOVA和回归分析发现，物种对宿主养分浓度、含量和化学计量有显著影响。Amphinema属物种对磷（P）、钙和锌浓度以及P含量有显著的正向影响；相比之下，土生棱柄盘菌对P浓度有负面影响。在未施肥处理中，Amphinema属物种的相对多度对叶片氮（N）浓度有负面影响，但对含量没有影响，并且降低了叶片的N/P。在施肥的幼苗中，Amphinema属物种与叶片中的N、镁和硼浓度以及锰的浓度和含量呈正相关，而Atheliaceae属物种与P含量呈负相关。这些发现揭示了群落和物种对幼苗状况的影响，揭示了优势物种之间明显的功能差异。所采用的方法应具有可扩展性，以探索由不可培养的外生菌根真菌组成的更复杂群落中的功能。
