K.M. Lwin, M.M. Myint, T. Tar, W.Z.M. Aung, Isolation of Plant Hormone (Indole-3-Acetic Acid – IAA). Producing Rhizobacteria and Study on their Effects on Maize Seed-ling, Eng. J. 16 (2012) 137–144.
L.E. de-Bashan, H. Antoun, Y. Bashan, Involvement of indole–3–acetic acid produced by the growth-promoting bacterium Azospirillum spp. In promoting growth of Chlorella vulgaris, J. Phycol. 44 (2008) 938–947.
In the synthesis of high-purity chemical intermediates for the food,cosmetic and pharmaceutical industries only the purest grades of benzoic acid can be used.
Gluconacetobacter diazotrophicus is an endophyte of sugarcane frequently found in plants grown in agricultural areas where nitrogen fertilizer input is low. Recent results from this laboratory, using mutant strains of G. diazotrophicus unable to fix nitrogen, suggested that there are two beneficial effects of G. diazotrophicus on sugarcane growth: one dependent and one not dependent on nitrogen fixation. A plant growth-promoting substance, such as indole-3-acetic acid (IAA), known to be produced by G. diazotrophicus, could be a nitrogen fixation-independent factor. One strain, MAd10, isolated by screening a library of Tn5 mutants, released only ~6% of the amount of IAA excreted by the parent strain in liquid culture. The mutation causing the IAA− phenotype was not linked to Tn5. A pLAFR3 cosmid clone that complemented the IAA deficiency was isolated. Sequence analysis of a complementing subclone indicated the presence of genes involved in cytochrome c biogenesis (ccm, for cytochrome c maturation). The G. diazotrophicus ccm operon was sequenced; the individual ccm gene products were 37 to 52% identical to ccm gene products of Escherichia coli and equivalent cyc genes of Bradyrhizobium japonicum. Although several ccm mutant phenotypes have been described in the literature, there are no reports of ccm gene products being involved in IAA production. Spectral analysis, heme-associated peroxidase activities, and respiratory activities of the cell membranes revealed that the ccm genes of G. diazotrophicus are involved in cytochrome c biogenesis.
Indole-3-acetic acid (IAA) is recognized as the key auxin in most plants and this phytohormone is critical for plant growth and orchestrates many developmental processes including cell enlargement and division, tissue differentiation, and responses to light and gravity [, ]. Diverse microorganisms including bacteria, fungi, and algae possess the ability to produce IAA. Interactions between IAA-producing bacteria and plants lead to diverse outcomes on the plant side, varying from pathogenesis to phytostimulation, and highlight the fact that bacteria use this phytohormone to interact with plants as part of their colonization strategy, including phytostimulation and circumvention of basal plant defense mechanisms .
In this context bacterial biosynthesis of the auxin phytohormone, indole-3-acetic acid (IAA) is well established, as it can positively regulate developmental processes of plant roots.
The standard technology of seed processing uses mainly chemical products. Recent researches showed that toxic materials from chemical fertilizers can be harmful to humans, animals and the environment. Currently the attention of researches is shifting away from chemical fertlizers and toward alternative that consumers perceive to be natural, Plant Growth Promoting bacteria (PGP). PGP bacteria could be a way to reduce chemical fertilizer doses. This was the reason to test the ability of Bacillus megaterium, Azotobacter chroococcum to produce hormone auxin (IAA). Bacterial strains were identified by PCR amplification and sequencing of the 16S rRNA gene. Indole-3-acetic acid (IAA) was detected and quantified by MRM experiment. This study conducted that maize seed inoculation with IAA from species mentioned above showed positive effects. They had statistically significantly higher root and steam height compared to control seedlings. Bacterial strains tested in this study may be recommended as PGP (Plant Growth Promoting) bacteria, due to their positive effects and eventually can be used to reduce chemical fertilizers doses.
...way for the biosynthesis of IAN in plants has been suggested, but not further examined (Normanly et al., 1993; Bartling et al., 1994). In bacteria such as Alcaligenes faecalis (Nagasawa et al., 1990; =-=Kobayashi et al., 1993-=-) nitrilases have been detected with specificity for indole-3-acetonitrile. In Ag. tumefaciens and Rhizobium spp., nitrile hydratase and amidase activity could be identified, indicating the conversion...
Technical Abstract: Production of the plant hormone indoleacetic-3-acid (IAA) is widespread among plant-associated microorganisms and it is important for pathogenesis in hyperplasia-inducing bacteria.
The role of plant-associated bacteria in plant physiology and metabolism is well documented, but little has been known about the roles played by Pseudomonas in durum wheat (Triticum turgidum L. var durum) growth and development. An in vitroexperiment was conducted to observe the effect of the inoculation of four indole-3-acetic acid (IAA)-producing Pseudomonas isolates and exogenous IAA on seed germination traits and α-amylase activity of durum wheat. The results showed inoculation with all bacterial isolates led to a decrease in the germination percent, although the extent of the depression varied with the isolate. A significant relationship between concentrations of bacterial IAA and the germination inhibition percent in durum wheat seeds by different bacteria strains was observed. The results of this assay showed the effect of bacterial isolates on α-amylase activity after six and 8 days of inoculation was significant, while effect of these isolates on α-amylase activity after two and 4 days of inoculation was not meaningful. In addition, the exogenously applied IAA displayed a concentration-dependent effect on seed germination attributes and α-amylase activity, consistent with the possibility that the inhibitory effect of bacterial inoculation on seed germination was in consequence of bacteria-produced IAA. Therefore, it may suggested that the inhibitory role of IAA in seed germination and α-amylase activity should be taken into account during the screening of IAA-producing Pseudomonas isolates for durum wheat growth promoting agents.
The indole-3-acetamide (IAM) pathway is employed mostly by pathogenic bacteria, and the indole-3-pyruvatic acid (IPyA) pathway is the major IAA biosynthesis pathway by plant growth-promoting bacteria.