Growth promotion of canola (rapeseed) seedlings by a strain of Pseudomonas putida under gnotobiotic conditions

Abstract

Inoculation of canola (Brassica campestris) seeds with a nitrogen-fixing strain of Pseudomonas putida (GR12-2) drastically increased the root length of seedlings grown in sterile growth pouches. Seed inoculation with inactive bacteria did not affect root lengths. Root elongation capacity was retained by nonnitrogen-fixing mutants of strain GR12-2. On the other hand, two other wild-type pseudomonads that do not fix nitrogen also increased root elongation. The addition of mineral nitrogen to the growth solution at concentrations of 1 mM or higher significantly inhibited root elongation of either inoculated or noninoculated seedlings. On the other hand, the addition of phosphate to the growth solution at similar concentrations stimulated root elongation of inoculated and noninoculated seedlings. The combined effects of bacterial inoculation and addition of phosphate on root and shoot elongation and on root and shoot weight were additive. Seed inoculation with P. putida GR12-2 increased the uptake of labelled phosphorus (32P) by seedlings grown in growth pouches and also enhanced the shoot elongation of seedlings grown in sterile soil. The capacity of P. putida GR12-2 to enhance phosphate uptake and to promote plant growth under gnotobiotic conditions may open the door to a new direction in the development of plant growth promoting inoculants.

Actinomycetes, promising tools to control plant diseases and to promote plant growth

“…It was in the course of biocontrol studies on plant disease suppression that some bacterial strains were found to promote plant growth even in the absence of pathogen antagonism (Harris et al 1994) and under gnotobiotic conditions (Lifshitz et al 1987). Thèse bénéficiai bacteria are known as plant growth promoting rhizobacteria, or PGPR (Kloepper et al 1989).…”

Potentiality of Native Pseudomonas spp. in Promoting Sugarcane Seedling Growth and Red Rot (Colletotrichum falcatum went) Management

“…Only few isolates could solubilize phosphate as shown by the formation of clear halos around the point of inoculation. IAA biosynthesis has been correlated with stimulation of root proliferation by rhizosphere bacteria, which enhanced uptake of nutrients by the associated plants (Lifishitz et al, 1987).…”

Mode d’action des rhizobactéries favorisant la croissance des plantes et potentiel de leur utilisation comme agent de lutte biologique

“…Diverses bactéries ont la capacité de solubiliser le phosphore organique par l'action de phosphatase, ou le phosphore inorganique par la libéra-tion d'acides organiques (Kloepper et al 1989). Les semences de canola (Brassica campestris L.) inoculées avec la RFCP, GR12-2, ont un contenu en phosphore supérieur aux témoins non-inoculés (Lifshitz et al 1987).…”