Effect of microbial diversity and their functions on soil nutrient cycling in the rhizosphere zone of Dahongpao mother tree and cutting Dahongpao

Abstract

Dahongpao mother tree (Camellia sinensis) is nearly 400 years old and is the symbol of Wuyi rock tea. It is unclear whether the structure and function of the rhizosphere soil microbial community of Dahongpao mother tree (MD) and its cutting Dahongpao (PD) change after planting. In this study, macrogenomics was used to analyze the structure and function of rhizosphere soil microbial communities, as well as to explore their relationship with soil nutrient transformations in MD and PD tea trees. The results showed that pH, total nitrogen, total phosphorus, total potassium, available nitrogen, available phosphorus and available potassium were significantly higher in the rhizosphere soil of MD than in PD by 1.22, 3.24, 5.38, 1.10, 1.52, 4.42 and 1.17 times, respectively. Secondly, soil urease, sucrase, protease, cellulase and catalase activities were also significantly higher in MD than in PD by 1.25-, 2.95-, 1.14-, 1.23-, and 1.30-fold. Macrogenomic analysis showed that rhizosphere soil microbial richness and diversity were higher in MD than in PD. There were eight characteristic microorganisms that significantly differed between MD and PD rhizosphere soils, and the results of functional analysis showed that MD rhizosphere soil microorganisms had higher carbon, nitrogen, and phosphorus biotransformation capacity, were more conducive to the accumulation and release of nutrients in the soil, and were more conducive to the promotion of tea tree growth. The results of PLS-SEM equation analysis showed that characteristic microorganisms positively regulated soil microbial function (1.00**), enzyme activity (0.84*) and nutrient content (0.82*). It can be seen that the abundance of soil characteristic microorganisms in the rhizospehre soil of MD increased significantly compared with that of PD, prompting a significant enhancement of their corresponding functions, which was more conducive to soil improvement, increased soil enzyme activity, enhanced soil nutrient biotransformation, and then increased soil nutrient accumulation and effectiveness, and promoted the growth of tea trees. This study provides an important theoretical basis for microbial regulation of tea tree cuttings management.

Keywords: macrogenomics; microbial diversity and function; soil enzyme; soil nutrient cycling; tea tree.

Figure 1

Basic physicochemical indexes and soil enzyme activities in rhizosphere soil of tea trees. MD: Dahongpao mother tree; PD: Cutting Dahongpao; (A) Soil basic physicochemical indexes; (B) Soil enzyme activities.

Figure 2

Core and pan gene dilution curve analysis of soil samples. (A) Dilution curve of core gene; (B) Dilution curve of pan gene.

Figure 3

Microbial diversity analysis of rhizosphere soil of tea tree. MD: Dahongpao mother tree; PD: Cutting Dahongpao; (A) Vane diagram analysis of soil genes; (B) Vane diagram analysis of soil microorganisms; (C) Analysis of variance of total abundance of soil microorganisms; (D) Analysis of α-diversity index; (E) PCoA analysis of β-diversity index; (F) Analysis of neutral community model of soil microorganisms; (G) Top ten soil microorganisms in terms of abundance at the phylum level; (H) Top ten soil microorganisms in terms of abundance at the genus level.

Figure 4

Modular interaction network node analysis of soil microorganisms in rhizosphere of tea tree. MD: Dahongpao mother tree; PD: Cutting Dahongpao; (A) analysis of modular interaction network of microorganisms; (B) analysis of keystone nodes of modular networks; (C) analysis of species abundance of keystone nodes of different modules; (D) The top ten microorganisms of keystone nodes in terms of abundance at phylum level; (E) The top ten microorganisms of keystone nodes in terms of abundance at genera level.

Figure 5

PLS-SEM equations of of microorganisms of different modules with soil basal physicochemical indexes and enzyme activities. “*” indicates a significant correlation between the two variables.

Figure 6

Screening of characteristic microorganisms in the rhizosphere soil of tea tree. MD: Dahongpao mother tree; PD: Cutting Dahongpao; (A) Volcano map to screen microorganisms significantly different from MD and PD and their abundance; (B) OPLS-DA model construction of MD and PD to screen key different microorganisms; (C) Bubble feature map to screen characteristic microorganisms; (D) the contribution of characteristic microorganisms to differentiating MD and PD by TOPSIS analysis; (E) Abundance analysis of characteristic microorganisms.

Figure 7

Functional analysis of characteristic microorganisms. (A) Enrichment analysis of characteristic microbial functions; (B) Microbial abundance analysis of functionally significant enrichment pathways.

Figure 8

Interaction analysis between different indexes. MD: Dahongpao mother tree; PD: Cutting Dahongpao; (A) RDA analysis of characteristic microorganisms and functions with different indexes; (B) Correlation network analysis of characteristic microorganisms and functions with different indexes; (C) Construction of PLS-SEM equations for characteristic microorganisms, microbial functions, soil enzyme activities and soil nutrients.

Figure 9

Effects of soil characteristic microorganisms and their functions on nutrient cycling in rhizosphere soil of tea tree.