Physiological evidence for differently regulated tryptophan-dependent pathways for indole-3-acetic acid synthesis in Azospirillum brasilense

2000 ◽  
Vol 264 (4) ◽  
pp. 521-530 ◽  
Author(s):  
R. Carreño-Lopez ◽  
N. Campos-Reales ◽  
C. Elmerich ◽  
B.E. Baca
Keyword(s):  
Acetic Acid ◽  
Azospirillum Brasilense ◽  
Acid Synthesis ◽  
Physiological Evidence ◽  
Indole 3 Acetic Acid

scholarly journals The Distribution of Tryptophan-Dependent Indole-3-Acetic Acid Synthesis Pathways in Bacteria Unraveled by Large-Scale Genomic Analysis

Molecules ◽  
2019 ◽  
Vol 24 (7) ◽  
pp. 1411 ◽  
Author(s):  
Pengfan Zhang ◽  
Tao Jin ◽  
Sunil Kumar Sahu ◽  
Jin Xu ◽  
Qiong Shi ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Large Scale ◽  
Growth Promotion ◽  
Plant Root ◽  
Genomic Analysis ◽  
Acid Synthesis ◽  
Metagenomic Data ◽  
Bacterial Genomes ◽  
Bacterial Phyla ◽  
Indole 3 Acetic Acid

Bacterial indole-3-acetic acid (IAA), an effector molecule in microbial physiology, plays an important role in plant growth-promotion. Here, we comprehensively analyzed about 7282 prokaryotic genomes representing diverse bacterial phyla, combined with root-associated metagenomic data to unravel the distribution of tryptophan-dependent IAA synthesis pathways and to quantify the IAA synthesis-related genes in the plant root environments. We found that 82.2% of the analyzed bacterial genomes were potentially capable of synthesizing IAA from tryptophan (Trp) or intermediates. Interestingly, several phylogenetically diverse bacteria showed a preferential tendency to utilize different pathways and tryptamine and indole-3-pyruvate pathways are most prevalent in bacteria. About 45.3% of the studied genomes displayed multiple coexisting pathways, constituting complex IAA synthesis systems. Furthermore, root-associated metagenomic analyses revealed that rhizobacteria mainly synthesize IAA via indole-3-acetamide (IAM) and tryptamine (TMP) pathways and might possess stronger IAA synthesis abilities than bacteria colonizing other environments. The obtained results refurbished our understanding of bacterial IAA synthesis pathways and provided a faster and less labor-intensive alternative to physiological screening based on genome collections. The better understanding of IAA synthesis among bacterial communities could maximize the utilization of bacterial IAA to augment the crop growth and physiological function.

A Prototype Model for Indole-3-Acetic Acid (IAA) Production by Azospirillum brasilense SP245

2004 ◽  
Vol 37 (9) ◽  
pp. 493-498 ◽  
Author(s):  
Ilse Y. Smets ◽  
Kristel Bernaerts ◽  
Astrid Cappuyns ◽  
Ositadinma Ona ◽  
Jos Vanderleyden ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Azospirillum Brasilense ◽  
Prototype Model ◽  
Iaa Production ◽  
Indole 3 Acetic Acid

Tryptophan conversion to indole-3-acetic acid via indole-3-acetamide in Azospirillum brasilense Sp7

1993 ◽  
Vol 39 (1) ◽  
pp. 81-86 ◽  
Author(s):  
Tami Bar ◽  
Yaacov Okon
Keyword(s):  
Molecular Weight ◽  
Acetic Acid ◽  
Azospirillum Brasilense ◽  
Soil Bacteria ◽  
Plant Interactions ◽  
Monooxygenase Activity ◽  
Azospirillum Brasilense Sp7 ◽  
Indole 3 Acetic Acid ◽  
Induced Proteins

The phytohormone indole-3-acetic acid is involved in several types of microorganism-plant interactions. In the most widely studied pathway, tryptophan-2-monooxygenase converts tryptophan to the intermediate indole-3-acetamide, and indole-3-acetamide hydrolase catalyzes the conversion of indole-3-acetamide to indole-3-acetic acid. The genetic determinants for these enzymatic conversions are iaaM and iaaH, respectively. This pathway has been observed in many pathogenic and symbiotic soil bacteria. The associative soil bacteria of the genus Azospirillum are known to promote plant growth, probably via the secretion of phytohormones, including indole-3-acetic acid. The following evidence is presented for the existence of the above-described indole-3-acetic acid pathway in Azospirillum brasilense Sp7: the high toxicity of α-methyltryptophan as compared with that of 5-methyltryptophan; indole-3-acetic acid formation in vivo from indole-3-acetamide; the existence of two tryptophan-induced proteins, one of which has a molecular weight similar to that of tryptophan-2-monooxygenase; tryptophan-2-monooxygenase activity observed on nondenaturing gel; the existence of a protein with high tryptophan-2-monooxygenase activity with a molecular weight similar to that of one of the tryptophan-induced proteins on a two-dimensional gel; and the partial homology between the iaaM gene, which encodes tryptophan-2-monooxygenase in Pseudomonas savastanoi, and A. brasilense Sp7 total DNA.Key words: Azospirillum brasilense Sp7, indole-3-acetic acid, tryptophan, indole-3-acetamide.

The Route, Control and Compartmentation of Auxin Synthesis

1993 ◽  
Vol 20 (5) ◽  
pp. 527 ◽  
Author(s):  
HM Nonhebel ◽  
TP Cooney ◽  
R Simpson
Keyword(s):  
Amino Acids ◽  
Acetic Acid ◽  
Recent Work ◽  
Aspartate Aminotransferase ◽  
Acid Synthesis ◽  
Pea Seedlings ◽  
Auxin Synthesis ◽  
Aromatic Aminotransferase ◽  
Work Supports ◽  
Indole 3 Acetic Acid

The study of indole-3-acetic acid synthesis has undergone something of a revival recently in an attempt to understand the control of IAA levels. Results are, however, contradictory with three separate hypotheses emerging. Our own work supports older evidence for L-tryptophan as the IAA precursor and appears to simplify the metabolism of tryptophan to IAA. Work comparing incorporation of 2H from 2H2O into IAA, tryptophan, tryptamine and indole-3-pyruvate in tomato shoots showed that the indole-3-pyruvate became labelled at a rate compatible with it being the sole intermediate between tryptophan and indole-3-acetaldehyde. Results also showed that tryptamine was not involved in IAA synthesis although it was present. Indole-3-acetaldoxime was not detected in tomato shoots. An aromatic aminotransferase able to catalyse the synthesis of indole-3-pyruvate has been purified from mung beans. This enzyme was separated from aspartate aminotransferase and is fairly specific for aromatic L-amino acids. Other work, however, has implicated D-tryptophan as a more direct precursor than the L-enantiomer. A D-tryptophan aminotransferase has been isolated from dark grown pea seedlings. Finally, other recent work has indicated the existence of an alternative biosynthetic route to IAA which does not involve tryptophan. These results are reviewed in this paper and the apparent contradictions between them discussed.

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