Department of Plant Ecology and Systematics, Lund University, Lund, Sweden.
FEMS Microbiol Ecol. 2010 Apr;72(1):125-31. doi: 10.1111/j.1574-6941.2009.00833.x.
The nutrient and carbon (C) allocation dynamics in mycorrhizal hyphal networks cause variation in costs and benefits for individual plants and fungi and influence the productivity, diversity and C cycling in ecosystems. We manipulated light and phosphorus (P) availability in a pot experiment with Trifolium subterraneum colonised by the arbuscular mycorrhizal (AM) fungus Glomus intraradices. Stable (13)C-labelling was used to trace assimilated CO(2) to the mycorrhizal fungus in roots and soil using compound-specific isotope ratio mass spectrometry. We used the neutral lipid fatty acid 16:1omega5 as a signature for AM fungal storage lipids. Both P and shading reduced the AM fungal lipid accumulation in the intraradical mycelium, while only P reduced the amount of lipids in the extraradical mycelium. Recently assimilated plant C was only allocated to the mycorrhizal fungus to a small extent when plant mycorrhizal benefit was reduced by P fertilization, while increasing the plant C cost by shading did not reduce the C flow to the fungus. These results are of importance for our conception of mycorrhizal dynamics during periods of shade in nature.
在丛枝菌根真菌网络中，养分和碳（C）的分配动态会导致个体植物和真菌的成本和收益发生变化，并影响生态系统的生产力、多样性和 C 循环。我们在一项盆栽实验中操纵了光和磷（P）的可利用性，该实验中三叶草被丛枝菌根（AM）真菌 Glomus intraradices 定殖。使用稳定的（13）C 标记，通过化合物特异性同位素比质谱法追踪根系和土壤中被 AM 真菌同化的 CO2。我们使用中性脂质脂肪酸 16:1ω5 作为 AM 真菌储存脂质的特征。P 和遮荫都会减少根内丛枝菌根真菌的脂质积累，而只有 P 会减少根外丛枝菌根真菌的脂质含量。当 P 施肥减少植物菌根效益时，最近同化的植物 C 仅少量分配给菌根真菌，而遮荫增加植物 C 成本并不会减少 C 流向真菌。这些结果对于我们理解自然遮荫期间菌根动态具有重要意义。
