AUTHOR=Wang Ning , Wang Luyao , Zhu Kai , Hou Sensen , Chen Lin , Mi Dandan , Gui Ying , Qi Yijun , Jiang Chunhao , Guo Jian-Hua 

TITLE=Plant Root Exudates Are Involved in Bacillus cereus AR156 Mediated Biocontrol Against Ralstonia solanacearum

JOURNAL=Frontiers in Microbiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2019.00098

DOI=10.3389/fmicb.2019.00098

ISSN=1664-302X

ABSTRACT=<p>The biological control process mediated by microbes relies on multiple interactions among plants, pathogens and biocontrol agents (BCAs). One such efficient BCA is <italic>Bacillus cereus</italic> AR156, a bacterial strain that controls a broad spectrum of plant diseases and potentially works as a microbe elicitor of plant immune reactions. It remains unclear, however, whether the interaction between plants and <italic>B. cereus</italic> AR156 may facilitate composition changes of plant root exudates and whether these changes directly affect the growth of both plant pathogens and <italic>B. cereus</italic> AR156 itself. Here, we addressed these questions by analyzing the influences of root exudate changes mediated by <italic>B. cereus</italic> AR156 during biocontrol against tomato bacterial wilt caused by <italic>Ralstonia solanacearum.</italic> Indeed, some upregulated metabolites in tomato root exudates induced by <italic>B. cereus</italic> AR156 (REB), such as lactic acid and hexanoic acid, induced the growth and motile ability of <italic>in vitro B. cereus</italic> AR156 cells. Exogenously applying hexanoic acid and lactic acid to tomato plants showed positive biocontrol efficacy (46.6 and 39.36%) against tomato bacterial wilt, compared with 51.02% by <italic>B. cereus</italic> AR156 itself. Furthermore, fructose, lactic acid, sucrose and threonine at specific concentrations stimulated the biofilm formation of <italic>B. cereus</italic> AR156 in Luria-Bertan- Glycerol- Magnesium medium (LBGM), and we also detected more colonized cells of <italic>B. cereus</italic> AR156 on the tomato root surface after adding these four compounds to the system. These observations suggest that the ability of <italic>B. cereus</italic> AR156 to induce some specific components in plant root exudates was probably involved in further biocontrol processes.</p>