Production of indole acetic acid by Kocuria rosea VB1 and Arthrobacter luteolus VB2 under the influence of L-tryptophan and maize root exudates

Abstract

Phytohormones play a very important role in enhancing plant growth by direct or indirect mechanisms involving plant-microbe interactions. Indole acetic acid (IAA) is one of the key phytohormones that directly enhance plant development. Kocuria rosea VB1 (GenBank ID: KY608093.1) and Arthrobacter luteolus VB2 (GenBank ID: KY608094.1) from polluted industrial water samples were characterized through a biochemical assay, 16S rDNA sequencing, and for promoting plant growth abilities. IAA production by VB1 and VB2 was tested in pure culture conditions supplemented with various L-tryptophan (Trp) concentrations (0, 50, 100, 200, and 500 μg @ ml !1). A significant difference in indole production by VB2 and VB1 inoculant at various L-Trp concentrations has been observed. VB1 has been reported to produce increased amounts of indole from 0.33 μg @ ml !1 to 18.16 μg @ ml !1 , while the increase in indole production was from 0.63 μg @ ml !1 to 9.22 μg @ ml !1 for VB2 for various L-Trp concentrations. The VB1 strain produced 85.07 ng @ ml !1 and 123.7 ng @ ml !1 IAA, whereas the VB2 strain produced 70.3 ng @ ml !1 and 78.4 ng @ ml !1 IAA, respectively at 200 and 500 μg @ ml !1 Trp concentrations. The growth pouch experiments with maize root exudates also showed a positive effect for both bacterial inoculants tested on IAA biosynthesis in comparison to non-inoculated seeds. Inoculation of maize seeds with VB2 and VB1 bacteria gave a significantly higher level of IAA production in comparison to non-inoculated seeds. Current study outcomes show the beneficial aspects of plant growth regulators produced by free-living bacteria which could play a significant role in plant growth promotion.

The potential of Burkholderia sp. form Zea mays roots as Plant Growth Promoting Rhizobacteria

“…Furthermore, the significant differences in plant growth parameters between the PGPR treatments with and without L-TRP indicate that L-TRP supplementation strengthens the effectiveness of PGPR in promoting plant growth. These findings are consistent with previous studies by Karnwal (2019), which demonstrate that the addition of L-TRP enhances PGPR colonization in plant roots. This improved colonization allows PGPR to interact more effectively with plants, facilitating the exchange of nutrients, hormones, and other biochemical signals between the two organisms (Chandran et al, 2021;Kalitkiewicz & Kȩpczyńska, 2008;Pac ocirc me et al, 2016;Shahzad et al, 2022;Tsukanova et al, 2017).…”

Isolation and Characterization of Plant Growth promoting Rhizobacteria from Bamboo Rhizosphere and Their Role in Plant Growth Promotion

“…Chin-A-Woeng et al (2000) reported that the ability of Pseudomonas isolates to suppress disease relies mainly on their ability to colonise roots. The positive impact of PGPR is to foster the crop growth and yield (Karnwal 2019). Fatima et al (2009) also proved that seed germination rate, growth of roots and wheat shoot were increased by inoculating bacterial IAA and PGPR.…”