Table 2.
Growth regulators produced by microorganisms, and their effect on plant development and morphology.
| Bacteria/fungi | Microbial phytohormones | Observed effects on explant | References |
|---|---|---|---|
| Bacillus megaterium MiR-4 | Auxins | Root elongation [Vigna radiata (L.) R. Wilczek] | Ali et al. (2009) |
| Pseudomonas putida | Auxins (IAA, IBA, and NAA) Cytokinins (BA or BAP; 2iP, KN, ZEA) |
Enhances biomass and essential oil production (Mentha piperita) Enhance resistance to osmotic stress (Pennisetum glaucum Zea mays) |
Santoro et al. (2015) and Patel and Saraf (2017) |
| Azospirillum brasilense Sp245, SR80, and A. halopraeferens | Auxins (IAA) | Increases the effectiveness of clonal micropropagation of potato (Solanum tuberosum L.) | Vettori et al. (2010) and Kargapolova et al. (2020) |
| A. brasilense spp. | Auxins | Root elongation and sprouts, number of roots (Arabidopsis thaliana) | Vega-Celedon et al. (2016) |
| Pseudomonas sp., Bacillus sp. | Auxins (IAA) | Root elongation [Arabidopsis thaliana (L.) Heynh.] | Asari et al. (2017) |
| Arthrobacter, Bacillus, Azospirillum, and Pseudomonas | Cytokinins (IBA and NAA) | Stimulated root biomass of Platycladus orientalis | Naz et al. (2009) and Liu et al. (2013) |
| Azospirillum lipoferum | Gibberellins (GA3) | Elongate the stem and shoots of A. glutinosa | Gutierrez-Manero et al. (2001) |
| Bacillus amyloliquefaciens | Gibberellins (GAs) | Improved rice (Oryza sativa L.) plant growth | Shahzad et al. (2016) |
| Azospirillum brasilense | Abscisic acid (ABA) | Help in plant-stress alleviation in Arabidopsis thaliana | Cohen et al. (2015) |
| Streptomyces sp. strain DBT204 | IAA and Kinetin (KN) | Enhancing growth of chili and tomato seedlings | Passari et al. (2016) |
| Fusarium strain | Auxin | Significant increase in growth and all tested growth parameters for Euphorbia pekinensis | Dai et al. (2008) |
| Ectomycorrhizal fungi (Astraeus odoratus, Gyrodon suthepensis, Phlebopus portentosus, Pisolithus albus, Pisolithus orientalis, and Scleroderma suthepense) | IAA | Increase the elongation of rice and oat (Avena fatua L.) coleoptiles | Kumla et al. (2020) |
CK, cytokinin; GB, gibberellin; IAA, indole-3-acetic acid; BAP, benzylaminopurine; ABA, abscisic acid; KN, kinetin; IBA, indole-3-butyric acid; NAA, naphthalene acetic acid; and ZEA, zeatin.