Effects of heavy metals and soil physicochemical properties on wetland soil microbial biomass and bacterial community structure

Pinus sylvestris var. mongolica is an important tree species for ecological construction and environmental restoration owing to its rapid growth rate and excellent stress resistance. Pinus sylvestris var. mongolica sphaeropsis blight is a widespread disease caused by Sphaeropsis sapinea. This study was focused on non-infected (CK) and infected (SS) Pinus sylvestris var. mongolica plants in Zhanggutai area, Liaoning Province, China. Illumina high-throughput sequencing based on the templates of sequencing-by-synthesis working with reversible terminators is a widely used approach. In the present study, systematic differences in relationships among rhizosphere soil physicochemical properties, bacterial community structure, diverse bacterial genera, and alpha diversity indices between the two categories were evaluated. The current findings are as follows: (1) Shannon’s index of SS soil was significantly higher than CK, and it was significantly lower in May than July and September (p < 0.05). (2) Non-metric multidimensional scaling (NMDS) showed a difference in bacterial community structure during May (spring), July (summer), and September. (3) At the phylum level, no significant difference was found in the bacterial genera between CK and SS soil for three seasons; however, at the genus level, there were about 19 different bacterial genera. The correlation studies between 19 different bacterial genera and environmental factors and α-diversity indicated that bacterial genera of non-infected and infected Pinus sylvestris var. mongolica were distributed differently. The bacterial genera with CK were positively correlated with soil physicochemical properties, while a negative correlation was found for SS. In conclusion, the differences in nutrient and microbial community structure in the rhizosphere soil of Pinus sylvestris var. mongolica are the main causes of shoot blight disease.

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Variation of rhizosphere bacterial community diversity in the desert ephemeral plant Ferula sinkiangensis across environmental gradients

10.21203/rs.2.18767/v1 ◽

2019 ◽

Author(s):

Zhang Tao ◽

Dang Han Li ◽

Wang Zhong Ke ◽

Lv Xin Hua ◽

Zhuang Li

Keyword(s):

Community Structure ◽

Bacterial Community ◽

Physicochemical Properties ◽

Bacterial Community Structure ◽

Soil Depth ◽

Community Diversity ◽

Slope Position ◽

Soil Physicochemical Properties ◽

Rhizosphere Bacterial Community ◽

Ferula Sinkiangensis

Abstract Background Ferula sinkiangensis is a desert short-lived medicinal plant, and its number is rapidly decreasing. Rhizosphere microbial community plays an important role in regulating global biogeochemical cycle, plant growth and adaptability. However, the Ferula sinkiangensis bacterial community and the processes that drive its assembly remain unclear. Results In this study, based on Illumina HiSeq high-throughput sequencing, we explored the diversity, structure and composition of Ferula sinkiangensis rhizosphere bacterial communities at different slope positions (upper, middle and bottom) and soil depths (0-10 cm, 10-25 cm, 25-40 cm) and their correlation with soil physicochemical properties. Actinobacteria (22.7%), Proteobacteria (18.6%), Acidobacteria (14.0%), Gemmatimonadetes (10.1%), Cyanobacteria (7.9%), Bacteroidetes (6.9%), Planctomycetes (3.9%), Verrucomicrobia (3.5%), Firmicutes (3.4%) and Chloroflexi (3.2%) were the dominant bacterial phyla in Ferula sinkiangensis rhizosphere soil. Variance analysis showed that the diversity and abundance of rhizosphere bacterial community in Ferula sinkiangensis were significantly different at various slope positions and soil depths. Specifically, the diversity of bacterial community was significantly higher at the top than the bottom of the slope, and the diversity and richness of bacterial community were significantly greater in the 0-10cm than the 25-40cm soil layer. Linear discriminant effect size (LEfSe) analysis showed the specific phyla and genera of bacteria affected by slope position and soil depth. For example, Planctomycetes, Sphingomonas , Rubrobacter and Adhaeribacter by slope position and significant impact on soil depth. In addition, distance-based redundancy analysis (db-RDA) and variance analysis showed that soil physicochemical factors jointly explained 29.81% of variation in Ferula sinkiangensis rhizosphere bacterial community structure. There was a significant positive correlation between available phosphorus（AP）and the diversity of Ferula sinkiangensis rhizosphere bacterial community ( p < 0.01), whereas pH largely explained the variation of Ferula sinkiangensis rhizosphere bacterial community structure (5.58%, p < 0.01), followed by altitude (5.53%), total salt (TS, 5.21%) and total phosphorus (TP, 4.90%). Conclusion Our results revealed the heterogeneity and variation trends of Ferula sinkiangensis rhizosphere bacterial community diversity and abundance on a fine spatial scale (slope position and depth) and shed new light on the interaction mechanisms between Ferula sinkiangensis rhizosphere bacterial community and soil physicochemical properties.

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