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Soil salinity is a serious environmental issue in arid China. Soil bacteria play a fundamental role in soil systems and respond rapidly to environmental changes. However, the responses of soil bacterial community to the different halophytes remains poorly understood. We investigated rhizosphere soil bacterial community changes under different halophytes in north China using high-throughput sequencing. Three typical halophytes were Leymus chinensis (LC), Puccinellia tenuiflora (PT), Suaeda glauca (SG). The dominant phyla were Proteobacteria, Actinobacteria, and Chloroflexi across three halophytic vegetation. These bacteria have important assistance for halophytes adapt to saline soil. PICRUSt forecasts demonstrated that energy metabolism, amino acid metabolism and carbohydrate metabolism are main bacterial functions in halophyte vegetation soil, and the abundance of metabolism these bacterial functions in SG was significantly higher than that in LC and PT. The pH value of different halophyte rhizosphere soils has a more significant effect on bacterial diversity than EC and soil trophic status, and soil water content (SWC) was important effect factors leading to differences in bacterial functions. These results give us a deeper understanding of the diversity and functional differences of rhizosphere soil bacterial communities in the typical halophytic vegetation of northern China.

Soil salinity is a serious environmental issue in arid China. Halophytes show extreme salt tolerance and are grow in saline-alkaline environments. There rhizosphere have complex bacterial communities, which mediate a variety of interactions between plants and soil. High-throughput sequencing was used to investigated rhizosphere bacterial community changes under the typical halophyte species in arid China. Three typical halophytes were Leymus chinensis (LC), Puccinellia tenuiflora (PT), Suaeda glauca (SG). The dominant phyla were Proteobacteria, Actinobacteria, Chloroflexi, Gemmatimonadetes, Acidobacteria and Bacteroidetes, Suaeda glauca rhizosphere has stronger enrichment of Nitrospirae and Cyanobacteria. The Ace, Chao and Shannon indices were significantly higher in soils under LC and SG (P<0.05). Functional predictions, based on 16S rRNA gene by PICRUSt, indicated that Energy metabolism, Amino acid metabolism, Carbohydrate metabolism and Fatty acid metabolism are dominant bacterial functions in three halophytes rhizosphere soil. Carbon metabolism, Oxidative phosphorylation, Methane metabolism, Sulfur metabolism and Nitrogen metabolism in SG were significantly higher than that in LC and PT. Regression analysis revealed that rhizosphere soil bacterial community structure is influenced by soil organic matter (SOM) and soil water content (SWC), while soil bacterial community diversity is affected by soil pH. This study contributes to our understanding of the distribution characteristics and metabolic functions under different halophyte rhizosphere bacterial communities, and will provide references for the use of rhizosphere bacteria to regulate the growth of halophytes and ecological restoration of saline soil.

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Purpose Maize/soybean intercropping is widely used as a vital practice to improve crop yields in northwest China. However, it is unknown how rhizosphere soil microbes regulate the P availability at the genetic level in maize/soybean intercropping. Methods We conducted an experiment to evaluate the effect of maize/soybean intercropping on rhizosphere soil P availability and P cycling functional genes using the BBP fractions and metagenomics methods. Soil samples were collected in the M, S, IM and IS. Results The SOC, TP, AP and PAC are improved in IM and IS. P fractions followed the order HCl-P > Citrate-P > Enzyme-P > CaCl2-P. The dominate soil microbial phyla were Proteobacteria, Actinobacteria, Acidobacteria, Chloroflexi and Planctomycetes. PCA and NMDS indicated that soil microbial composition differed among treatments. The abundance of phoD, ppa, ppx and pstC upregulated in the IM, the random forest analysis showed that these genes have the highest explanation for AP, suggesting that the improved availability in IM may due to the upregulation of these genes. RDA analysis indicated that pH, SMBP significantly correlated with P fractions, indicating that pH and SMBP are important factors in influencing soil P bioavailability. Inorganic P solubilization, regulatory and transporter genes were correlated with soil pH, TP and ALP, suggesting they were the key factors affecting the expression of functional genes related to soil P cycling. Conclusion Maize/soybean intercropping can increase rhizosphere soil P bioavailability. Although there are relationships between soil AP and microbial genes (phoD, ppa, ppx,and pstC), soil properties are more crucial than genes in shaping soil P bioavailability.