Lysinibacillus spp.: An IAA-producing endospore forming-bacteria that promotes plant growth

Authors: PANTOJA-GUERRA, MANUAL - University Of Antioquia; BURKETT-CADENA, MARLENY - Plant Response Biotechnology; CADENA, JOHANNA - Plant Response Biotechnology; Dunlap, Christopher; RAMIREZ, CAMILO - University Of Antioquia

Submitted to: Antonie Van Leeuwenhoek
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/29/2023
Publication Date: 5/3/2023
Citation: Pantoja-Guerra, M., Burkett-Cadena, M., Cadena, J., Dunlap, C.A., Ramirez, C.A. 2023. Lysinibacillus spp.: An IAA-producing endospore forming-bacteria that promotes plant growth. Antonie Van Leeuwenhoek. 116: 615-630. https://doi.org/10.1007/s10482-023-01828-x.
DOI: https://doi.org/10.1007/s10482-023-01828-x

Interpretive Summary: Microbes can be used to enhance or promote the growth of plants and are often used to encourage even and rapid root growth. In this study, an ARS researcher from Peoria, IL, collaborated with scientists from Colombia to characterize a group of bacteria on their ability to promote plant growth in corn and the ability to produce plant hormones. The study demonstrated that most of the bacteria from the genus Lysinibacillus were capable of promoting plant growth. This research expands our knowledge of how microbes interact with plants and provides the data needed to justify larger field trials. This research benefits corn and other row crops growers in the United States by developing new products to enhance crop growth and yields.

Technical Abstract: Lysinibacillus is a bacterial genus that has generated growing interest for its biotechnological potential. Strains belonging to this group are recognized for their mosquitocidal activity and bioremediation activity for the purification of contaminated environments. However, in recent years some reports indicate its agrobiotechnological importance as plant growth promoting rhizobacteria (PGPR). This research sought to provide evidence of the PGP activity of Lysinibacillus spp. and the role of the indole-3-acetic acid (IAA) production associated with this activity. Twelve Lysinibacillus spp. strains were evaluated under greenhouse conditions, six of which increased the biomass and root architecture of corn plants. In most cases, growth stimulation was evident at 108 cfu/ml inoculum concentration. All strains produced IAA with high variation between them (20 - 70 mg/mL). The bioinformatic identification of predicted genes associated with IAA production allowed the detection of the indole pyruvic acid pathway to synthesize IAA in all strains; additionally, genes for a tryptamine pathway were detected in two strains. In a coleoptile elongation test, extracellular filtrates from all strain’s cultures increased the coleoptile length in an IAA-similar concentration pattern, which demonstrates the filitrates had an auxin-like effect on plant tissue. Five of the six strains that previously showed PGPR activity in corn also promoted the growth of Arabidopsis thaliana (col 0). These strains also induced changes in root architecture of Arabidopsis mutant plants (aux1-7/axr4-2), the partial reversion of mutant phenotype indicated the role of IAA on plant growth. This work provided evidence of the role of Lysinibacillus spp. IAA production on their PGP activity. These elements contribute to the agrobiotechnological exploration of this genus.