Gene Expression Profile of a Plant Growth Promoting Rhizobacterium Bacillus atrophaeus UCMB-5137 in Response to Maize Root Exudate Stimulation

摘要

Plant Growth Promoting Rhizobacteria (PGPR) are widely used in agriculture as an ecologically safe replacement of chemical pesticides and fertilizers. In this work, gene expression regulation under stimulation by maize root exudate was studied in a PGPR strain Bacillus atrophaeus UCMB-5137. A strong up-regulation of synthesis of (p)ppGpp (guanosine pentaphosphate) alarmone was observed. This alarmone is associated with the stringent response in bacteria, but its involvement in regulation of plant colonization has never been reported. Comparison of the profiles of gene expression at the classical stringent response and in the current experiment showed only a partial overlap that allowed us to make a conclusion that the tested bacteria had not been starved but responded specifically to the root exudate stimulation and (p)ppGpp alarmone is involved in this complex response. Comparison of the gene expression regulation in B. atrophaeus UCMB-5137 with a report obtained on a similar experiment with another PGPR strain B. amyloliquefaciens FZB42 showed that these two closely related organisms had used different strategies of plant colonization.