Lin Litao, Chen Yun, Xu Guorui, Zhang Yuxin, Zhang Shuang, Ma Keming
State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China.
University of Chinese Academy of Sciences, Beijing, China.
Front Microbiol. 2021 Mar 9;12:626671. doi: 10.3389/fmicb.2021.626671. eCollection 2021.
Cities are prone to ecological problems, yet the impacts of rapid global urbanization on the feedback between above- and belowground subsystems remain largely unknown. We sampled the roots of 8 common herbaceous plants within the Fifth Ring (urban areas) and in Jiufeng National Forest Park (rural areas) in Beijing (China) to assess the impacts of urbanization on the network of plant-arbuscular mycorrhizal (AM) fungal associations. Using Illumina MiSeq sequencing, 81 AM fungal OTUs were identified in 78 herb root samples. The Shannon, Simpson, and Pielou indices of root AM fungi in urban areas were significantly higher than those in rural areas. In this study, a significantly nested mycorrhizal association network was observed in rural areas (NODF = 64.68), whereas a non-nested pattern was observed in urban areas (NODF = 55.50). The competition index C-score (0.0769) of AM fungi in urban areas was slightly lower than that in rural areas (0.1431), and the species specialization (') of 8 host plants and fungal dissimilarity among 8 host plants in urban areas were significantly lower than those in rural areas. Convergent associations among hosts may be an important factor influencing this non-nested pattern of the plant-AM fungi network in urban areas. Generalists, rather than specialists, were enhanced during the establishment of mycorrhizal associations in urban areas. Our results suggest that reduced selectivity of host plants, and generalist promotion and specialist reduction of AM fungi during urbanization may contribute to the non-nested network of plant-AM fungal associations.
城市容易出现生态问题，然而全球快速城市化对地上和地下子系统之间反馈的影响在很大程度上仍不为人知。我们在中国北京的五环路以内（市区）和鹫峰国家森林公园（农村地区）对8种常见草本植物的根系进行了采样，以评估城市化对植物-丛枝菌根（AM）真菌共生网络的影响。通过Illumina MiSeq测序，在78个草本植物根系样本中鉴定出81个AM真菌操作分类单元。市区根系AM真菌的香农指数、辛普森指数和皮洛指数显著高于农村地区。在本研究中，农村地区观察到显著的嵌套菌根共生网络（NODF = 64.68），而市区观察到非嵌套模式（NODF = 55.50）。市区AM真菌的竞争指数C分数（0.0769）略低于农村地区（0.1431），市区8种寄主植物的物种专一性（）以及8种寄主植物之间的真菌差异显著低于农村地区。寄主之间的趋同共生可能是影响市区植物-AM真菌网络这种非嵌套模式的一个重要因素。在市区菌根共生建立过程中，广适性物种而非专一性物种得到增强。我们的结果表明，城市化过程中寄主植物选择性降低以及AM真菌广适性增强和专一性降低可能导致了植物-AM真菌共生的非嵌套网络。
