AUTHOR=Zhou Liuting , Li Jianjuan , Pokhrel Ganga Raj , Chen Jun , Zhao Yanlin , Bai Ying , Zhang Chen , Lin Wenxiong , Wu Zeyan , Wu Chengzhen 

TITLE=nifH Gene Sequencing Reveals the Effects of Successive Monoculture on the Soil Diazotrophic Microbial Community in Casuarina equisetifolia Plantations

JOURNAL=Frontiers in Plant Science

VOLUME=11

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2020.578812

DOI=10.3389/fpls.2020.578812

ISSN=1664-462X

ABSTRACT=<p>The growth and productivity of <italic>Casuarina equisetifolia</italic> is negatively impacted by planting sickness under long-term monoculture regimes. In this study, Illumina MiSeq sequencing targeting <italic>nifH</italic> genes was used to assess variations in the rhizospheric soil diazotrophic community under long-term monoculture rotations. Principal component analysis and unweighted pair-group method with arithmetic means (UPGMA) clustering demonstrated distinct differences in diazotrophic community structure between uncultivated soil (CK), the first rotation plantation (FCP), the second rotation plantation (SCP), and the third rotation plantation (TCP). Taxonomic analysis showed that the phyla <italic>Proteobacteria</italic> increased while <italic>Verrucomicrobia</italic> decreased under the consecutive monoculture (SCP and TCP). The relative abundance of <italic>Paraburkholderia</italic>, <italic>Rhodopseudomonas</italic>, <italic>Bradyrhizobium</italic>, <italic>Geobacter</italic>, <italic>Pseudodesulfovibrio</italic>, and <italic>Frankia</italic> increased significantly while <italic>Burkholderia</italic>, <italic>Rubrivivax</italic>, and <italic>Chlorobaculum</italic> declined significantly at the genus level under consecutive monoculture (SCP and TCP). Redundancy analysis (RDA) showed that <italic>Burkholderia, Rubrivivax</italic>, and <italic>Chlorobaculum</italic> were positively correlated with total nitrogen and available nitrogen. In conclusion, continuous <italic>C. equisetifolia</italic> monoculture could change the structure of diazotrophic microbes in the rhizosphere, resulting in the imbalance of the diazotrophic bacteria population, which might be a crucial factor related to replanting disease in this cultivated tree species.</p>