Integrated network analysis reveals the importance of microbial interactions for maize growth
Microbes play a critical role in soil global biogeochemical circulation and microbe–microbe interactions have also evoked enormous interests in recent years. Utilization of green manures can stimulate microbial activity and affect microbial composition and diversity. However, few studies focus on the microbial interactions or detect the key functional members in communities. With the advances of metagenomic technologies, network analysis has been used as a powerful tool to detect robust interactions between microbial members. Here, random matrix theory-based network analysis was used to investigate the microbial networks in response to four different green manure fertilization regimes (Vicia villosa, common vetch, milk vetch, and radish) over two growth cycles from October 2012 to September 2014. The results showed that the topological properties of microbial networks were dramatically altered by green manure fertilization. Microbial network under milk vetch amendment showed substantially more intense complexity and interactions than other fertilization systems, indicating that milk vetch provided a favorable condition for microbial interactions and niche sharing. The shift of microbial interactions could be attributed to the changes in some major soil traits and the interactions might be correlated to plant growth and production. With the stimuli of green manures, positive interactions predominated the network eventually and the network complexity was in consistency with maize productivity, which suggested that the complex soil microbial networks might benefit to plants rather than simple ones, because complex networks would hold strong the ability to cope with environment changes or suppress soil-borne pathogen infection on plants. In addition, network analyses discerned some putative keystone taxa and seven of them had directly positive interactions with maize yield, which suggested their important roles in maintaining environmental functions and in improving plant growth.
KeywordsGreen manures Microbial networks Microbial interactions Keystone species Maize yield
The study was supported by the National Nature Science Foundation of China (nos. 31570113 and 41573072). We acknowledge Xiangxi Tabacco Test Base for providing experimental fields for this study and are grateful to the facilities and conditions provided by Key Laboratory of Biometallurgy of Ministry of Education, School of Minerals Processing and Bioengineering, Central South University, Changsha, China. Thanks to Profs. Huaqun Yin, Juan Li, and Xueduan Liu who helped design this study and contributed material essential for the study; to Jiemeng Tao who wrote the manuscript; to Chong Qin, Yabing Gu, and Yili Liang for their help finish this experiment; to Yunhua Xiao for data analysis; and to Delong Meng and Zhenghua Liu for language revision.
Compliance with ethical standards
This article does not contain any studies with human participants or animals performed by any of the authors.
Conflict of interest
All authors declare that they have no competing interests.
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