Significant changes in arbuscular mycorrhizal community and soil physicochemical properties during the saline-alkali grassland vegetation succession

Arbuscular mycorrhizal(AM)fungi are widely distributed in various habitats,and the community composition varies in response to the changing environmental conditions.To explore the response of community composition to the succession of saline-alkali land,soil samples were collected from three succession stages of Songnen saline-alkali grassland.Subsequently,the soil characteristics were determined and the AM fungi in soil samples were analyzed by high-throughput sequencing.Then,the response relationship between community composition and soil characteristics was studied by Canonical correlation and Pearson analyses.The soil properties improved with the succession of saline-alkali grassland.There was no significant difference in alpha diversity between the first and second succession stage(Suaeda glauca and Puccinellia tenuiflora,respectively),and the microbial community had a dense association network at the third stage(Leymus chinensis);in addition,each succession stage had significantly enriched amplicon sequence variants(ASVs)and functional pathways.All the soil properties except cellulase activity had significant effects on community composition.Furthermore,the pH,organic carbon,organic matter,and sucrase activity significantly correlated with alpha diversity indices.These results provide a theoretical basis for realizing the significant changes in AM fungal community and soil properties during the saline-alkali grassland vegetation succession.

Comparison of soil bacterial diversity and community composition between clear-cut logging and control sites in a temperate deciduous broad-leaved forest in Mt. Sambong, South Korea

Deforestation or clear-cut logging affects forest ecosystems,including soil microbial communities.The purpose of this study was to investigate the effects of clearcut logging on the soil bacterial community in a temperate deciduous broad-leaved forest on Mt.Sambong,South Korea.We investigated the physicochemical characteristics and bacterial diversity of the soil in clear-cut logging and control sites.The available phosphorus(AP)level in soil was significantly lower in the clear-cut sites than in the control;however,the other physicochemical properties of soil were similar at the two sites.By examining the bacterial 16S rRNA gene using next-generation sequencing,we found that the number of bacterial taxa at the species and phylum level were similar at the control and clear-cut sites.Consistent with the high resilience of bacterial communities and absence of change in the soil physicochemical properties—with the exception of AP—we found similar levels of bacterial diversity at the two sites.Although most taxa showed similar composition ratios at the control and the clear-cut sites,some taxa such as Deltaproteobacteria,Ktedonobacteriales,Myxocccales,Polyangiaceae,Pedosphaera_f,and Solibacter showed differences after clear-cut logging.We conclude that AP was significantly associated with those bacterial taxa that showed differences in their composition ratios following clear-cut logging.

Integrated analysis reveals an association between the rhizosphere microbiome and root rot of arecanut palm

The rhizosphere microbial community is crucial to plant health.Many studies have explored the association between the rhizosphere microbiome and plant disease.However,few studies have focused on root rot in arecanut palm,a disease causing devastating effects and thus resulting in economic losses that considerably affect the development of the arecanut industry.Here,rhizosphere samples were collected from both healthy arecanut palm plants and root-rotted arecanut palm plants,and the microbial communities were analyzed using high-throughput sequencing.The root-rotted samples exhibited distinct microbial community richness,diversity,and composition compared with the healthy samples,which was associated with p H according to the Mantel test.Identified potential plant pathogens,including Proteobacteria,Bacteroidetes,Chytridiomycota,and Mortierellomycota,were significantly enriched in the root-rotted samples.In contrast,potentially beneficial plant microbes,such as Acidobacteria and Gemmatimonadetes,were significantly depleted in the root-rotted samples.Co-occurrence networks were constructed to further identify microbial relationships in the root-rotted samples.These findings revealed ecological imbalance among beneficial bacteria in the root-rotted samples.The present study therefore provides an integrated view of the association between the microbial community and root rot in arecanut palm.