Production of indole-3-acetic acid, aromatic amino acid aminotransferase activities and plant growth promotion by Pantoea agglomerans rhizosphere isolates

Abstract

The production of auxins, such as indole-3-acetic acid (IAA), by rhizobacteria has been associated with plant growth promotion, especially root initiation and elongation. Six indole-producing bacteria isolated from the rhizosphere of legumes grown in Saskatchewan soils and identified as Pantoea agglomerans spp. were examined for their ability to promote the growth of canola, lentil and pea under gnotobiotic conditions and for tryptophan (Trp)-dependent IAA production. Five of the isolates enhanced root length, root weight or shoot weight by 15-37% in at least one of the plant species, but isolates 3-117 and 5-51 were most consistent in enhancing plant growth across the three species. Indole concentrations in the rhizosphere of plants grown under gnotobiotic conditions increased in the presence of the rhizosphere isolates and when Trp was added 3 days prior to plant harvest. Isolates 3-117, 5-51 and 5-105 were most effective in increasing rhizosphere indole concentrations. Colony hybridization confirmed that all of the isolates possessed the ipdC gene which codes for a key enzyme in the Trpdependent IAA synthetic pathway.

Isolation and Characterization of Highly Effective Phytate-Mineralizing Klebsiella pneumonia Strain MK1C Adapted to Arid and Semiarid Conditions from Calcareous Soil

“…Further future studies are needed to answer such questions. This is an agreement with other the solubilization of P was due to the production of organic acids (Dastager et al, 2010;Pandey et al, 2006), siderophore (Sharma et al, 2013), indole acetic acids (Sergeeva et al, 2007), phytase (Acu?a and Jorquera, 2011;Konietzny and Greiner, 2004), and protons during ammonia respiration Ramesh et al, 2014;Reyes et al, 2006).…”

Importance of Endophytic Strains Pantoea agglomerans in the Biological Control of Rhizoctonia solani

“…Cimmino et al [40] analysed 5 strains of P. agglomerans which produced low amount of IAA in the range of 5.4 to 13.2 µg/cm 3 in the presence of 500 µg/cm 3 of L-tryptophan in the medium after 4 days of incubation. Also in the research of Sergeeva et al [41] all of six isolates P. agglomerans produced IAA when L-tryptophan was present in the culturing medium. The concentrations of produced IAA increased with increasing concentrations of L-tryptophan, reaching a maximum at 250 µg/cm 3 for isolates 2-54, 3-117, 5-105 and GR12-2, and at 500 µg/cm 3 for isolates 2-32, 4-20 and 5-51.…”

Rhizosphere competent Pantoea agglomerans enhances maize (Zea mays) and chickpea (Cicer arietinum L.) growth, without altering the rhizosphere functional diversity

“…Similar to our results, earlier also many PGP strains from Pantoea sp. were reported for phytohormone production (Feng et al 2006;Sergeeva et al 2007, Dastager et al 2009) and phosphate solubilization IAA production / P-solubilization (µg/ml) 0 20 40 60 80 100 IAA production P-solbilization 30 0 C 2% NaCl pH-9 37 0 C 4% NaCl Fig. 2 Indole acetic acid (IAA) production and phosphate solubilization of P. agglomerans NBRISRM under in vitro conditions.…”