Rhizosphere microbial ecological characteristics of strawberry root rot

Abstract

Introduction: Strawberry (Fragaria × ananassa Duch.) holds a preeminent position among small fruits globally due to its delectable fruits and significant economic value. However, strawberry cultivation is hampered by various plant diseases, hindering the sustainable development of the strawberry industry. The occurrence of plant diseases is closely linked to imbalance in rhizosphere microbial community structure.

Methods: In the present study, a systematic analysis of the differences and correlations among non-culturable microorganisms, cultivable microbial communities, and soil nutrients in rhizosphere soil, root surface soil, and non-rhizosphere soil of healthy and diseased strawberry plants affected by root rot was conducted. The goal was to explore the relationship between strawberry root rot occurrence and rhizosphere microbial community structure.

Results: According to the results, strawberry root rot altered microbial community diversity, influenced fungal community composition in strawberry roots, reduced microbial interaction network stability, and enriched more endophytic-phytopathogenic bacteria and saprophytic bacteria. In addition, the number of bacteria isolated from the root surface soil of diseased plants was significantly higher than that of healthy plants.

Discussion: In summary, the diseased strawberry plants changed microbial community diversity, fungal species composition, and enriched functional microorganisms significantly, in addition to reshaping the microbial co-occurrence network. The results provide a theoretical basis for revealing the microecological mechanism of strawberry root rot and the ecological prevention and control of strawberry root rot from a microbial ecology perspective.

Keywords: Fragaria × ananassa Duch.; culturable microorganisms; high-throughput sequencing; microbial network; root rot.

Figure 1

Microbial alpha diversity. The α-diversity indices of soil fungal (A) and bacterial (B) communities in the root surface soil and rhizosphere soil of healthy and diseased strawberry plants. (C,D) Comparison of beta diversity related to root surface soil and rhizosphere soil between healthy and diseased strawberry plants, (C) fungal beta diversity; (D) Bacterial beta diversity. Alpha diversity: The horizontal bars within boxes represent medians. The tops and bottoms of boxes represent the 75th percentiles and 25th percentiles, respectively. The asterisk above the horizontal line represents a significant difference between the two groups, ^*p < 0.05, ^**p < 0.01, and ^***p < 0.001. Beta diversity: Different color points represent the samples in each group, and the circle in the figure is a confidence ellipse at a confidence level of 95%.

Figure 2

Microbial community composition of the root surface soil and rhizosphere soil of healthy and diseased strawberry at the phylum level, (A) fungal community composition; (B) Bacterial community composition.

Figure 3

Visualizations of microbial co-occurrence networks in different soil samples. The nodes are colored according to bacterial phylum and fungal phylum. The circle surrounded by nodes represents the module. Edge color represents positive (green) and negative (red) correlations.

Figure 4

(A) Zi–Pi plot shows the distribution of OTUs based on their topological roles with different soil samples. (B) Changes in the natural connectivity of different soil samples.

Figure 5

(A) Prediction results of root surface soil and rhizosphere soil FAPROTAX function of healthy and diseased strawberry plants, (B) Prediction results of root surface soil and rhizosphere soil FUNGuild function of healthy and diseased strawberry plants. The abscissa of the left histogram represents the average relative abundance of a feature in different groups. The ordinate represents the grouping category of different features or pairwise comparison in the task group. Different colors represent different groupings. The rightmost is p-value, ^*0.01 < p < 0.05, ^**0.001 < p < 0.01, ^***p < 0.001.

Figure 6

(A) Isolation frequency of the bacteria with different soil samples. (B) Community composition of culturable bacteria at phylum level in different soil samples.