Guillen Thais, Kessler Michael, Homeier Jürgen
Department of Systematic and Evolutionary Botany University of Zurich Zurich Switzerland.
Faculty of Resource Management University of Applied Sciences and Arts (HAWK) Göttingen Germany.
Plant Environ Interact. 2024 Mar 29;5(2):e10139. doi: 10.1002/pei3.10139. eCollection 2024 Apr.
Ferns are known to have a lower incidence of mycorrhization than angiosperms. It has been suggested that this results from carbon being more limiting to fern growth than nutrient availability, but this assertion has not been tested yet. In the present study, we took advantage of a fertilization experiment with nitrogen and phosphorus on cloud forest plots of the Ecuadorean Andes for 15 years. A previous analysis revealed changes in the abundances of fern species in the fertilized plots compared to the control plots and hypothesized that this might be related to the responses of the mycorrhizal relationships to nutrient availability. We revisited the plots to assess the root-associated fungal communities of two epiphytic and two terrestrial fern species that showed shifts in abundance. We sampled and analyzed the roots of 125 individuals following a metabarcoding approach. We recovered 1382 fungal ASVs, with a dominance of members of Tremellales (Basidiomycota) and Heliotales (Ascomycota). The fungal diversity was highly partitioned with little overlap between individuals. We found marked differences between terrestrial and epiphytic species, with the latter fundamentally missing arbuscular mycorrhizal fungi (AMF). We found no effect of fertilization on the diversity or relative abundance of the fungal assemblages. Still, we observed a direct impact of phosphorus fertilization on its concentration in the fern leaves. We conclude that fern-fungi relationships in the study site are not restricted by nutrient availability and suggest the existence of little specificity on the fungal partners relative to the host fern species.
众所周知，蕨类植物菌根形成的发生率低于被子植物。有人认为，这是因为碳对蕨类植物生长的限制比对养分有效性的限制更大，但这一断言尚未得到验证。在本研究中，我们利用了在厄瓜多尔安第斯山脉云雾林地块上进行的为期15年的氮磷施肥实验。先前的一项分析揭示了施肥地块与对照地块相比蕨类植物物种丰度的变化，并推测这可能与菌根关系对养分有效性的反应有关。我们再次访问这些地块，以评估两种附生蕨类植物和两种地生蕨类植物的根系相关真菌群落，这些蕨类植物的丰度出现了变化。我们采用宏条形码方法对125个个体的根系进行了采样和分析。我们共获得了1382个真菌扩增子序列变体（ASV），其中以银耳目（担子菌门）和胶膜菌目（子囊菌门）的成员为主。真菌多样性高度分化，个体之间几乎没有重叠。我们发现地生蕨类植物和附生蕨类植物之间存在显著差异，后者基本上没有丛枝菌根真菌（AMF）。我们发现施肥对真菌群落的多样性或相对丰度没有影响。不过，我们观察到施磷对蕨类植物叶片中磷的浓度有直接影响。我们得出结论，研究地点的蕨类植物与真菌的关系不受养分有效性的限制，并表明相对于宿主蕨类植物物种，真菌伙伴之间的特异性较低。
