图2. 几种植物养分捕获策略的形态示意图。A, 丛枝菌根真菌Glomus caledonium的菌丝体从豆科宿主Trifolium repens的根系向土壤生长。B, 微宇宙培育的松科植物Pinus sylvestris的幼苗与外生菌根真菌Suillus bovinus共生。可以看到在微宇宙中真菌菌丝在土壤中扩散(箭头头部)并且局部增殖形成清晰致密的斑块(箭头)。C, Woollsia pungens的欧石南类菌根表皮被欧石南类菌根真菌的菌丝套侵染(箭头表示被蓝色染色)。D, 豆科植物Astragalus mahoshanicus的根瘤。E, 山龙眼科植物Banksia grandis的排根。图片由钟宏韬拍摄。F, 杜鹃花科植物Actinocephalus cabralensis的固沙根。G, 莎草科植物Tetraria的胡萝卜状根。H, Velloziaceae植物Barbacenia tomentosa田间采集的毛状根。图A引自Olsson等(2002); 图B、C、G引自Lambers等(2008); 图F引自Oliveira等(2015); 图H引自Abrahão等(2020)。

Fig. 2. Morphology of plant nutrient-acquisition strategies. A, Hyphae of the arbuscular mycorrhizal fungus Glomus caledonium growing into soil from a host root of Trifolium repens (Fabaceae). Photo by Iver Jakobsen; reprinted with permission of Springer-Verlag (Olsson et al., 2002). B, A seedling of Pinus sylvestris (Pinaceae) growing in a microcosm in association with the ectomycorrhizal fungus Suillus bovinus. The fungal mycelium can be seen spreading in the soil in the microcosm (arrowhead) and proliferating locally to form well-defined dense patches (arrows). Reprinted with permission of Elsevier B.V. (Lambers et al., 2008). C, Ericoid mycorrhizal root of Woollsia pungens, showing epidermal cells colonized by coils of an ericoid mycorrhizal fungus (stained blue, arrowed). Reprinted with permission of Elsevier B.V. (Lambers et al., 2008). D, Nodules of Astragalus mahoshanicus (Fabaceae). E, Cluster roots of Banksia grandis (Proteaceae). Photo by ZHONG Hong-Tao. F, Sand-binding roots of Actinocephalus cabralensis (Ericaulaceae)(Oliveira et al., 2015). G, Dauciform roots of Tetraria species (Cyperaceae). Reprinted with permission of Elsevier B.V. (Lambers et al., 2008). H, Vellozioid roots of Barbacenia tomentosa (Velloziaceae) collected in field (Abrahão et al., 2020). EMF, ericoid mycorrhizal fungus; RE, root epidermis; RVS, root vascular system.