Biochar Suppresses Bacterial Wilt of Tomato by Improving Soil Chemical Properties and Shifting Soil Microbial Community.

Yang Gao,Weipeng Lin,Yang Lu,Jihui Tian,Kunzheng Cai

doi:10.3390/microorganisms7120676

Abstract

The role of biochar amendments in enhancing plant disease resistance has been well documented, but its mechanism is not yet fully understood. In the present study, 2% biochar made from wheat straw was added to the soil of tomato infected by Ralstonia solanacearum to explore the interrelation among biochar, tomato bacterial wilt resistance, soil chemical properties, and soil microbial community and to decipher the disease suppression mechanisms from a soil microbial perspective. Biochar application significantly reduced the disease severity of bacterial wilt, increased soil total organic carbon, total nitrogen, C:N ratio, organic matter, available P, available K, pH, and electrical conductivity. Biochar treatment also increased soil acid phosphatase activity under the non-R.-solanacearum-inoculated condition. High-throughput sequencing of 16S rRNA revealed substantial differences in rhizosphere bacterial community structures between biochar-amended and nonamended treatments. Biochar did not influence soil microbial richness and diversity but significantly increased the relative abundance of Bacteroidetes and Proteobacteria in soil at the phylum level under R. solanacearum inoculation. Furthermore, biochar amendment harbored a higher abundance of Chitinophaga, Flavitalea, Adhaeribacter, Pontibacter, Pedobacter, and Ohtaekwangia at the genus level of Bacteroides and Pseudomonas at the genus level of Proteobacteria under R. solanacearum inoculation. Our findings suggest that a biochar-shifted soil bacterial community structure can favorably contribute to the resistance of tomato plants against bacterial wilt.

Highlights

Bacterial wilt, caused by Ralstonia solanacearum, is a bacterial soilborne disease that is commonly observed among Solanaceous crops [1]
Total organic carbon (TOC), total nitrogen (TN), C:N ratio (C/N), soil organic matter (SOM), pH, and electrical conductivity (EC) in biochar-treated soil were changed by 1.53, 1.26, 1.51, 1.53, 1.10, and 3.45-fold, respectively, for non-R.-solanacearum inoculation (BC) compared with CK, and 1.44, 1.13, 1.45, 1.46, 1.10, and 3.29-fold, respectively, for R. solanacearum inoculation (Rs + Biochar amendment only (BC)) compared with Rs
Wheat biochar amendment significantly reduced the disease severity of bacterial wilt caused by R. solanacearum, thereby confirming our previous findings that biochar can be used as an amendment to control bacterial wilt [32]

Summary

Introduction

Bacterial wilt, caused by Ralstonia solanacearum, is a bacterial soilborne disease that is commonly observed among Solanaceous crops [1]. This disease is likely to occur under high temperatures and humid conditions and can persist for a long time [2]. The traditional methods for controlling bacterial wilt mainly focus on resistant species, biological control, chemical control, and soil anaerobic disinfection [3,4,5]. These methods may have limited or negative effects on food safety and the environment. Applying biochar could alleviate the plant diseases caused by soilborne pathogens [19,20,21] and significantly reduce the incidence of Fusarium wilt in tomato [22], as well as bacterial wilt in both tomato [23] and tobacco [24]

Methods

Results

Conclusion