First, second, third, fourth, fifth, sixth, and eighth authors: College of Life Sciences and Fujian Provincial Key Laboratory of Agroecological Processing and Safety Monitoring; seventh and eighth authors: Key Laboratory of Crop Ecology and Molecular Physiology, Fujian Province University; and seventh author: College of Crop Science, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, P.R. China.
Phytopathology. 2018 Dec;108(12):1493-1500. doi: 10.1094/PHYTO-02-18-0038-R. Epub 2018 Nov 5.
Consecutive monoculture of Rehmannia glutinosa in the same field leads to a severe decline in both quality and yield of tuberous roots, the most useful part in traditional Chinese medicine. Fungi are an important and diverse group of microorganisms in the soil ecosystem and play crucial roles in soil health. In this study, high-throughput pyrosequencing of internal transcribed spacer 2 ribosomal DNA amplicons was applied to gain insight into how consecutive monoculture practice influence and stimulate R. glutinosa rhizosphere and bulk soil fungal communities. The results from nonmetric multidimensional scaling ordination and clustering analysis revealed distinctive differences between rhizosphere and bulk soil fungal communities. However, longer-term monocultured bulk soils were more similar to the rhizosphere soils in comparison with the shorter-term monocultured bulk soils. Moreover, consecutive monoculture caused a gradual shift in the composition and structure of the soil fungal community. The cultivation of this plant led to the appearance of some exclusive operational taxonomic units in rhizosphere or bulk soils that were assigned to the genera Fusarium, Rhizoctonia, and so on. Furthermore, the sum of the relative abundance of species of Fusarium, Cylindrocarpon, and Gibberella (belonging to the family Nectriaceae); Rhizoctonia, Thanatephorus, and Ceratobasidium (belonging to the family Ceratobasidiaceae); and Lectera and Plectosporium (belonging to the family Plectosphaerellaceae) was significantly higher in consecutively monocultured (CM) than in newly planted (NP) soil in both rhizosphere and bulk soils. In particular, Fusarium abundance was significantly higher in CM than in NP in the rhizosphere, and higher in rhizosphere soils than in bulk soils for each treatment. A pathogenicity test showed that both Fusarium strains isolated were pathogenic to R. glutinosa seedlings. In addition, the culture filtrate and mycotoxins produced by Fusarium oxysporum significantly repressed the growth of the antagonistic bacterium, Pseudomonas aeruginosa. In conclusion, consecutive monoculture of R. glutinosa restructured the fungal communities in both rhizosphere and bulk soils but bulk effects developed more slowly over time in comparison with rhizosphere effects. Furthermore, microbial interactions might lead to a reduction in the abundance of beneficial microbes.
连续在同一块土地上单一种植地黄会导致其根茎的质量和产量严重下降，而根茎是中药中最有用的部分。真菌是土壤生态系统中重要且多样化的微生物群，在土壤健康中发挥着关键作用。在这项研究中，应用高通量内部转录间隔区 2 核糖体 DNA 扩增子焦磷酸测序技术，深入了解连续单一种植实践如何影响和刺激地黄的根际和土壤真菌群落。非度量多维标度排序和聚类分析的结果表明，根际和土壤真菌群落之间存在明显差异。然而，与短期单种土壤相比，长期单种土壤的根际土壤更相似。此外，连续单种导致土壤真菌群落的组成和结构逐渐发生变化。该植物的种植导致了一些在根际或土壤中特有的操作分类单元的出现，这些分类单元被分配到镰刀菌属、立枯丝核菌属等属。此外，镰刀菌属、刺盘孢属和赤霉属（属于核盘菌科）；丝核菌属、Thanatephorus 和 Ceratobasidium（属于丝核菌科）；以及 Lectera 和 Plectosporium（属于小丛壳科）的物种相对丰度之和在根际和土壤中连续单种（CM）土壤中显著高于新种植（NP）土壤。特别是，在根际中，CM 中镰刀菌的丰度显著高于 NP，且每个处理中根际土壤中的丰度都高于土壤。致病性试验表明，从连续单种的地黄中分离出的两种镰刀菌菌株均对地黄幼苗具有致病性。此外，尖孢镰刀菌产生的培养液和真菌毒素显著抑制了拮抗细菌铜绿假单胞菌的生长。总之，连续单种地黄重构了根际和土壤中的真菌群落，但与根际效应相比，土壤效应随时间的推移发展得更缓慢。此外，微生物相互作用可能导致有益微生物丰度的减少。
