151. A Bacillus subtilis sensor kinase involved in triggering biofilm formation on the roots of tomato plants
- Author
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Richard Losick, Shugeng Cao, Jon Clardy, Yunrong Chai, Yun Chen, Jian-Hua Guo, and Roberto Kolter
- Subjects
biology ,Kinase ,fungi ,Biofilm ,food and beverages ,Bacillus subtilis ,biochemical phenomena, metabolism, and nutrition ,biology.organism_classification ,Microbiology ,Small molecule ,Cell biology ,Extracellular matrix ,Biochemistry ,Signalling molecules ,Extracellular ,Molecular Biology ,Bacteria - Abstract
Summary The soil bacterium Bacillus subtilis is widely used in agriculture as a biocontrol agent able to protect plants from a variety of pathogens. Protection is thought to involve the formation of bacterial communities – biofilms – on the roots of the plants. Here we used confocal microscopy to visualize biofilms on the surface of the roots of tomato seedlings and demonstrated that biofilm formation requires genes governing the production of the extracellular matrix that holds cells together. We further show that biofilm formation was dependent on the sensor histidine kinase KinD and in particular on an extracellular CACHE domain implicated in small molecule sensing. Finally, we report that exudates of tomato roots strongly stimulated biofilm formation ex planta and that an abundant small molecule in the exudates, L-malic acid, was able to stimulate biofilm formation at high concentrations in a manner that depended on the KinD CACHE domain. We propose that small signalling molecules released by the roots of tomato plants are directly or indirectly recognized by KinD, triggering biofilm formation.
- Published
- 2012