Effects of integrated biocontrol on bacterial wilt and rhizosphere bacterial community of tobacco

Abstract

Bacterial wilt as a soil-borne disease was caused by Ralstonia solanacearum, and seriously damages the growth of tobacco. Integrated biocontrol method was explored to control bacterial wilt. Nevertheless, the long-term effects of the integrated biocontrol method on soil bacterial community, soil physicochemical properties and the incidence of bacterial wilt are not well understood. In this study, B. amyoliquefaciens ZM9, calcium cyanamide and rice bran were applied to tobacco fields in different ways. The disease index and incidence of tobacco bacterial wilt (TBW), soil physicochemical properties, colonization ability of B. amyoliquefaciens ZM9, and rhizopshere bacterial community were investigated. The results showed that the integrated application of B. amyoliquefaciens ZM9, rice bran and calcium cyanamide had the highest control efficiency of TBW and bacteria community diversity. Additionally, the integrated biocontrol method could improve the colonization ability of B. amyoliquefaciens ZM9. Furthermore, the integrated biocontrol method could effectively suppress TBW by regulating soil physicochemical properties, promoting beneficial bacteria and antagonistic bacteria of rhizopshere soil. This strategy has prospect of overcoming the defects in application of a single antagonistic bacteria and provides new insights to understand how to improve the colonization capacity of antagonistic bacteria and control efficacy for TBW.

Exogenous Application of Sodium Hydrosulfide Suppresses Bacterial Wilt And Regulates The Soil Microecology

“…Then the soil samples from the ve separate sites were mixed to one soil sample, partitioned into two subsamples, ones were immediately transported on ice to the laboratory and stored at − 80°C for genomic DNA extraction, and the other subsamples were air-dried for physicochemical properties analysis. The analysis of soil pH, alkali-hydrolyzed nitrogen (AN), available phosphorus (AP), available potassium (AK), organic matter (OM), exchangeable calcium (Ca) and exchangeable magnesium (Mg) was performed according to Hu et al 52 Bacterial wilt recording. Symptoms of TBW were monitored at ve different sites in each plot at 100 d post-transplantation.…”

“…Symptoms of TBW were monitored at ve different sites in each plot at 100 d post-transplantation. The TBW disease index (DI) based on severity scale of 0-9 was described in a previous study 52 . Brie y, "0" represents the plants without visible symptoms; "1" represents the presence of occasional chlorotic spots on stems, or less than half of the leaves wilted on unilateral stems; "3" represents the presence of a black streak less than half the height of the stem, or between half to twothirds of the leaves wilted on unilateral stems; "5" represents the presence of a black streak over half the length of the stem, but not reaching the top of the stem, or more than two-thirds of the leaves wilted on unilateral stems; "7" represents the presence of a black streak reaching the top of the stem, or all leaves wilted; and "9" represents the dead plant.…”

“…The integrity of DNA samples were determined by 1% agarose gel electrophoresis. Then the concentration and purity of the DNA were determined using a Nanodrop 1000 spectrophotmeter (Nanodrop Techenologies, Wilmington, DE, USA) 52 .…”

“…The OTUs, Chao1 and Shannon index were calculated with QIIME (Version 1.7.0) to evaluate richness and diversity of soil microbial community 52 .…”

Genomic insights on fighting bacterial wilt by a novel Bacillus amyloliquefaciens strain Cas02

“…Each treatment included three replicates of 15 plants per replicate. The disease index was scored using the following scale (Hu et al ., 2021 ): Level 0: no diseased leaves; Level 1: less than one‐half of the leaves withered; Level 3: one‐half to two‐thirds of the leaves withered; Level 5: more than two‐thirds of the leaves withered; Level 7: all leaves withered; Level 9: the plant is basically dead. …”