Potential rhizospheric bacteria benefit tobacco health during the incidence of tobacco black shank disease

Abstract

Plant health is closely related to microbial communities present in specific host increasingly challenged by pathogen attack. Soil-borne diseases cause an imbalance of the already colonized plant rhizosphere microbial community, resulting in restricting agricultural production. In this study, tobacco black shank (TBS), caused by Phytophthora nicotianae was used as a disease model to explore the impact of rhizosphere microorganisms on tobacco health and assessed the use of introduced microbes to mitigate the spread of disease in an environment-friendly way. Here, field investigation confirmed that the higher pathogen load in the field was directly proportional to the higher disease index. We isolated 223 strains of bacteria from the tobacco rhizosphere soil in Yuxi City, Yunnan, China and confirmed eight candidate strains with potential antagonism against P. nicotianae. The strains were further identified as Bacillus based on morphology, physiological and biochemical characteristics, and molecular analysis. Under field conditions, sterilized and non-sterilized rhizospheric soil showed significant differences in terms of pathogen growth. Our results indicated potential bacteria in the tobacco rhizosphere have a protective effect against TBS. Notably, eight potential Bacillus strains and simple synthetic microbial consortium as the antagonistic group could reduce the number of the pathogen in soil effectively and resist the TBS in the greenhouse. P. nicotianae and rhizosphere antagonists co-affect tobacco health, and proved that potential microbes could effectively reduce a load of P. nicotianae and control plant diseases in an ecological friendly way for plant health and protection.

Keywords

• Plant health
• Tobacco black shank
• Phytophthora nicotianae
• Antagonistic bacteria
• Biological control