Methods for Improving PGPR Establishment.

Plant growth-promoting rhizobacteria (PGPR) are often touted as a useful means to improve crop productivity and sustainability.  However, field studies with PGPR inoculants often result in limited PGPR establishment and colonization, highlighting the need to better understand the factors involved in successful PGPR establishment.  In this study, we examined the establishment and colonization of Arabidopsis roots by the PGPR Pseudomonas putida following various soil treatments aimed at removing various components of the soil bacterial community.  Treatments included antibiotics (chloramphenicol, rifampin), autoclaving, and nutrient amendments with all treatments significantly altering the residual bacterial community abundance (ANOVA, p < 0.05).  Interestingly, P. putida colonization was highly correlated with the residual bacterial community abundance across all treatments (R² = 0.564) suggesting that colonization can be improved by the creation of empty spaces regardless of the disruption technique.  Additional recommendations for soil microbial community management and successful PGPR establishment will also be discussed.