Plant growth promotion induced by phosphate solubilizing endophytic Pseudomonas isolates

Abstract

The use of plant growth promoting bacterial inoculants as live microbial biofertilizers provides a promising alternative to chemical fertilizers and pesticides. Inorganic phosphate solubilization is one of the major mechanisms of plant growth promotion by plant associated bacteria. This involves bacteria releasing organic acids into the soil which solubilize the phosphate complexes converting them into ortho-phosphate which is available for plant up-take and utilization. The study presented here describes the ability of endophytic bacteria to produce gluconic acid (GA), solubilize insoluble phosphate, and stimulate the growth of Pisum sativum L. plants. This study also describes the genetic systems within three of these endophyte strains thought to be responsible for their effective phosphate solubilizing abilities. The results showed that many of the endophytic strains produced GA (14–169 mM) and have moderate to high phosphate solubilization capacities (~400–1300 mg L−1). When inoculated into P. sativum L. plants grown in soil under soluble phosphate limiting conditions, the endophytes that produced medium-high levels of GA displayed beneficial plant growth promotion effects.

Isolation and selection of plant growth-promoting bacteria associated with sugarcane

“…Although rhizobacteria are the most promising as biofertilizers, phosphate solubilizing endophytic bacteria are also described. Oteino et al (2015) demonstrated that the inoculation of endophytes into the rhizosphere increased growth in plants suffering from limited phosphate supply.…”

Impact of Soil Salinity on Diversity and Community of Sugarcane Endophytic Plant Growth Promoting Bacteria (Saccharum Officinarum L. Var. Cp48)

“…According to previous studies Pseudomonas, Bacillus, Rhizobium, Micrococcus and Erwinia are reported as phosphate solubilizer bacteria (Rodriguez and Fraga, 1999). Pseudomonas and Bacillus have been screened inorganic phosphate solubilizing isolates from Pisumsativum L. plants (Oteino et al, 2015). Among the reported phosphate solubilizing bacteria, Bacillus and Pseudomonas are the most important bacteria (Chauhan et al, 2013;Sharma et al, 2013).…”

Comparative genomic, proteomic and exoproteomic analyses of three Pseudomonas strains reveals novel insights into the phosphorus scavenging capabilities of soil bacteria

“…One advantage of utilizing P‐liberating bacteria in agricultural systems is that they can have synergistic beneficial effects, for example, pathogen suppression (Vassilev et al ., 2006). The majority of research into P mobilization by PGPR has focused on the solubilization of inorganic P through acidification of the surrounding soil via the release of organic acids, namely gluconic acid (Rodrı'guez and Fraga, 1999; Miller et al ., 2010; Oteino et al ., 2015). The genus Pseudomonas represents one soil bacterial group that is frequently associated with plant‐growth promotion, including P solubilization (Miller et al ., 2010).…”