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

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.

Streptomyces sp. strain TOR3209: a rhizosphere bacterium promoting growth of tomato by affecting the rhizosphere microbial community

“…As the bacteria enriched by TOR3209 inoculation in the early fruit setting stage, Janthinobacterium and Collimonas are well known for their antifungal effects 62 – 64 , while Agrobacterium might be phytopathogen, endophytes or symbionts of plants depending the strain-specific properties 65 , 66 . In the last growth stage, TOR3209 inoculation increased the abundance of Micrococcaceae _NA, Agromyces , Adhaeribacter , Pontibacter and Pseudomonas , which formed microbial composition similar to that reported by Gao et al 67 , suggesting them a biochar-shifted soil bacterial community favorably contributing to the resistance of tomato plants against bacterial wilt. In general, the microbes in rhizobacterial community up-regulated by TOR3209 were mainly the plant growth promoting and disease-resistant bacteria.…”

“…These five strains have great potential in promoting plant growth (Fig. 4) and a large number of studies have proved the growth promoting ability of related strains 67,[72][73][74][75][76] . The dominant differential strains screened by non-culture methods (Fig.…”

Biochar-Mediated Control of Phytophthora Blight of Pepper Is Closely Related to the Improvement of the Rhizosphere Fungal Community

“…Biochar demonstrated its possibility as a control agent against Phytophthora blight of pepper, supporting similar control effects of soilborne diseases observed in previous studies (Jaiswal et al, 2017;Zhang et al, 2017;Gao et al, 2019;Jaiswal et al, 2019;Chen et al, 2020). Furthermore, biochar applied before planting showed a significantly higher control effect than that applied 20 days before planting, indicating its declining control effect with prolonged application time prior to pepper planting.…”

“…However, the mechanisms remain unknown. Biochar-induced soil chemical properties are closely associated with the control of diseases caused by soilborne bacteria (Zhang et al, 2017;Gao et al, 2019;Chen et al, 2020), but whether it is conducive to the control of diseases caused by oomycetes needs to be explored.…”

“…Recent studies have shown that biochar application can effectively control soilborne plant diseases caused by pathogenic fungi and bacteria, such as Fusarium oxysporum , Rhizoctonia solani , and Ralstonia solanacearum ( Jaiswal et al, 2014 , 2015 ; Elmer, 2016 ; Zhang et al, 2017 ; Gao et al, 2019 ; Chen et al, 2020 ). Our previous study first reported that the addition of biochar to soil resulted in a good control effect of Phytophthora blight of pepper, caused by the pathogenic oomycete Phytophthora capsici L. ( Wang et al, 2017 ).…”