Comparative Proteomics Analysis of Bacillus amyloliquefaciens SQR9 Revealed the Key Proteins Involved in in Situ Root Colonization

Bacillus Amyloliquefaciens SQR9
is a well-investigated plant growth-promoting rhizobacteria with strong
root colonization capability. To identify the key proteins involved
in in situ root colonization and biofilm formation, the proteomic
profiles of planktonic and root colonized SQR9 cells were compared.
A total of 755 proteins were identified, of which 78 and 95 proteins
were significantly increased and deceased, respectively, when SQR9
was colonized on the root. The proteins that were closely affiliated
with the root colonization belonged to the functional categories of
biocontrol, detoxification, biofilm formation, cell motility and chemotaxis,
transport, and degradation of plant polysaccharides. A two-component
system protein ResE was increased 100-fold when compared to the planktonic
status; impairment of the resE gene postponed the
formation of cell biofilm and decreased the root colonization capability,
which may be regulated through the spo0A-sinI-yqxM pathway. The SQR9 proteomic data
provide valuable clues for screening key proteins in the plant–rhizobacteria
interaction.