Auxin production by plant associated bacteria: impact on endogenous IAA content and growth of Triticum aestivum L

Abstract

Aims: The aim of this study was to investigate the potential of bacterial strains of Bacillus, Pseudomonas, Escherichia, Micrococcus and Staphylococcus genera associated with wild herbaceous flora to enhance endogenous indole-3-acetic acid (IAA) content and growth of Triticum aestivum var. Inqalab-91.

Methods and results: Gas chromatography and mass spectrometric (GC-MS) analysis revealed that bacterial strains produced 0.6-8.22 microg IAA ml(-1) in the presence of L-tryptophan. Plant microbe experiments showed a significant positive correlation between auxin production by bacterial strains and endogenous IAA content of T. aestivum for GC-MS (r = 0.618; P = 0.05) and colorimetric analysis (r = 0.693; P = 0.01). Similarly, highly significant positive correlation for shoot length (r = 0.627; P = 0.01) and shoot fresh weight (r = 0.626; P = 0.01) was observed with auxin production under axenic conditions. Bacterial inoculations also enhanced shoot length (up to 29.16%), number of tillers (up to 97.35%), spike length (up to 25.20%) and seed weight (up to 13.70%) at final harvest.

Conclusions: Bacterial strains have the ability to increase the endogenous IAA content and growth of T. aestivum var. Inqalab-91.

Significance and impact of the study: Microbial strains of wild herbaceous flora can be effectively used to enhance the growth and yield of agronomically important crops.