On the Mechanism of Action of 2, 4-Dichlorophenoxyacetic Acid

1949 ◽  
Vol 2 (2) ◽  
pp. 154 ◽  
Author(s):  
PL Goldacre
Keyword(s):  
Mechanism Of Action ◽  
Enzyme Preparation ◽  
Plant Hormone ◽  
Structural Similarity ◽  
Economic Importance ◽  
Dichlorophenoxyacetic Acid ◽  
Crude Enzyme Preparation ◽  
Rate Limiting ◽  
Indole 3 Acetic Acid ◽  
Fundamental Mechanism

The use of synthetic plant growth-regulating compounds is of increasing economic importance in agriculture but little is known of their fundamental mechanism of action. The hormone-like character and general structural similarity of certain substituted aryl-acetates and -oxyacetates or their potential precursors (Zimmerman and Hitchcock 1941-42) to that of indole-3-acetic acid (LA.A.) suggest that these compounds may act indirectly by altering the activity of this natural plant hormone. Tang and Bonner (1947) have partially characterized an enzyme prepared from pea epicotyls (and referred to here as LA.A. oxidase) which oxidizes and inactivates LA.A. On adding 11 auxin analogues to a crude enzyme preparation they found no change in the rate of LA.A. inactivation. However, as these workers used a substrate (LA.A.) concentration that was rate-limiting, the only rate-change necessarily to be detected would have been a decrease due to competition with the substrate.

Production and Properties of a Bacterial Thermostable Exo-inulinase

2001 ◽  
Vol 56 (11-12) ◽  
pp. 1022-1028 ◽  
Author(s):  
Kristina Uzunova ◽  
Anna Vassileva ◽  
Margarita Kambourova ◽  
Viara Ivanova ◽  
Dimitrina Spasova ◽  
...  
Keyword(s):  
Enzyme Production ◽  
Enzyme Preparation ◽  
Batch Cultivation ◽  
Crude Enzyme ◽  
Growth Time ◽  
Bacillus Sp ◽  
High Thermostability ◽  
Crude Enzyme Preparation ◽  
Ph Range

Abstract Enzyme production of newly isolated thermophilic inulin-degrading Bacillus sp. 11 strain was studied by batch cultivation in a fermentor. The achieved inulinase and invertase activi­ ties after a short growth time (4.25 h) were similar or higher compared to those reported for other mesophilic aerobic or anaerobic thermophilic bacterial producers and yeasts. The investigated enzyme belonged to the exo-type inulinases and splitted-off inulin, sucrose and raffinose. It could be used at temperatures above 65 °C and pH range 5.5-7.5. The obtained crude enzyme preparation possessed high thermostability. The residual inulinase and inver­ tase activities were 92-98% after pretreatment at 65 °C for 60 min in the presence of substrate inulin.

scholarly journals Biochemical and Genetic Bases of Indole-3-Acetic Acid (Auxin Phytohormone) Degradation by the Plant-Growth-Promoting Rhizobacterium Paraburkholderia phytofirmans PsJN

2016 ◽  
Vol 83 (1) ◽  
Author(s):  
Raúl Donoso ◽  
Pablo Leiva-Novoa ◽  
Ana Zúñiga ◽  
Tania Timmermann ◽  
Gonzalo Recabarren-Gajardo ◽  
...  
Keyword(s):  
Energy Source ◽  
Gene Regulation ◽  
Acetic Acid ◽  
Plant Growth ◽  
Plant Hormone ◽  
Content Type ◽  
Gene Functions ◽  
Plant Growth Promoting ◽  
Growth Promoting ◽  
Indole 3 Acetic Acid

ABSTRACT Several bacteria use the plant hormone indole-3-acetic acid (IAA) as a sole carbon and energy source. A cluster of genes (named iac) encoding IAA degradation has been reported in Pseudomonas putida 1290, but the functions of these genes are not completely understood. The plant-growth-promoting rhizobacterium Paraburkholderia phytofirmans PsJN harbors iac gene homologues in its genome, but with a different gene organization and context than those of P. putida 1290. The iac gene functions enable P. phytofirmans to use IAA as a sole carbon and energy source. Employing a heterologous expression system approach, P. phytofirmans iac genes with previously undescribed functions were associated with specific biochemical steps. In addition, two uncharacterized genes, previously unreported in P. putida and found to be related to major facilitator and tautomerase superfamilies, are involved in removal of an IAA metabolite called dioxindole-3-acetate. Similar to the case in strain 1290, IAA degradation proceeds through catechol as intermediate, which is subsequently degraded by ortho-ring cleavage. A putative two-component regulatory system and a LysR-type regulator, which apparently respond to IAA and dioxindole-3-acetate, respectively, are involved in iac gene regulation in P. phytofirmans. These results provide new insights about unknown gene functions and complex regulatory mechanisms in IAA bacterial catabolism. IMPORTANCE This study describes indole-3-acetic acid (auxin phytohormone) degradation in the well-known betaproteobacterium P. phytofirmans PsJN and comprises a complete description of genes, some of them with previously unreported functions, and the general basis of their gene regulation. This work contributes to the understanding of how beneficial bacteria interact with plants, helping them to grow and/or to resist environmental stresses, through a complex set of molecular signals, in this case through degradation of a highly relevant plant hormone.

scholarly journals Response of pine hypocotyl sections to growth regulators and related substances

2015 ◽  
Vol 44 (1) ◽  
pp. 123-132
Author(s):  
J. Zakrzewski
Keyword(s):  
Acetic Acid ◽  
Growth Regulators ◽  
Growth Response ◽  
Extended Period ◽  
Dichlorophenoxyacetic Acid ◽  
Pinus Silvestris ◽  
Related Substances ◽  
2,4 Dichlorophenoxyacetic Acid ◽  
Indole 3 Acetic Acid ◽  
Synthetic Growth

Growth response of <i>Pinus silvestris</i> hypocotyl sections to some synthetic growth regulators and related substances was studied. Elongation of hypocotyl sections was stimulated by naphtaleneacetic acid, indole-3-acetic acid, in-dole-3-propionic acid, indole-3-butyric acid, 2,4-dichlorophenoxyacetic acid, indoleaoetic amide, indoleacetic nitrile and coumarin. Indole-3-acetic acid and naphtaleneacetic acid extended period of growth up to 16 and 24 hours, respectively. Growth was inhibited by kinetin, trans-cinnamic acid and 2,3,5-tri-iodobenzoic acid. No effect of gibberellic acid, tryptophan and biotin was observed.

scholarly journals Annual variations in the microflora of some varieties of Finnish malting barley

1995 ◽  
Vol 4 (4) ◽  
pp. 407-418
Author(s):  
Tapani Tuominen ◽  
Heikki Rosenqvist
Keyword(s):  
Plant Hormone ◽  
Growing Season ◽  
Fungal Species ◽  
Consistent Difference ◽  
Malting Barley ◽  
Microbial Infection ◽  
Microbial Counts ◽  
Annual Variations ◽  
Average Rainfall ◽  
Indole 3 Acetic Acid

Three major Finnish malting barley varieties were studied for annual variations in the incidence of seed-derived fungi, bacteria and actinomycetes. In 1990-1992, 114 characterized fungal, 59 uncharacterized bacterial and 12 uncharacterized actinomycetal isolates were extracted from samples of seed intended for use in malting. When the yield of the plant hormone, indole-3-acetic acid (lAA), from enriched microbial cultures was weighed against the microbial biomass and the endogenous lAA concentration of the barley harvests, it was concluded that potential exists for bacterial lAA production in biologically significant amounts, given some minor annual variations. As expected from the average rainfall and temperature during the growing season, microbial counts in all cultivars were highest in 1992. Most of the fungal species found were of saphrophytic character, and field fungi were dominant in the samples. On the whole, microbial counts and spectra in all samples confirmed that each harvest of all cultivars was of good vigour and well suited for malting purposes. Strains of plant pathogenic character included species of Septoria nodorum (Berk) Berk, Drechlera teres (Sacc) Subraim & Jain, D. sorokiniana (Sacc) Subram & Jain and D. graminea (Rab.) Shoem. A consistent difference was noted in the microbial infection severities of the cultivars.

scholarly journals Changes in Leaf-Sugar Content and Enzyme Activity of Immature Sugarcane Following Foliar Application of Indole-3-Acetic Acid, 2,4-Dichlorophenoxyacetic Acid, and Maleic Hydrazide

1969 ◽  
Vol 49 (1) ◽  
pp. 1-34
Author(s):  
Alex G. Alexander
Keyword(s):  
Acetic Acid ◽  
Maleic Hydrazide ◽  
Foliar Application ◽  
Sugar Content ◽  
Water Soluble ◽  
Dichlorophenoxyacetic Acid ◽  
Enzyme Preparations ◽  
Freeze Dried ◽  
2,4 Dichlorophenoxyacetic Acid ◽  
Indole 3 Acetic Acid

Indole-3-acetic acid, 2,4-dichlorophenoxyacetic acid, and maleic hydrazide were applied as foliar sprays to 10-week-old sugarcane plants during initial studies of the interrelationships of growth-regulating materials with the sugar-metabolizing enzymes of sugarcane. Leaf samples were harvested at 1, 3, 9, and 27 days following treatment for sugar and enzyme assays. Sugar analyses were run for total ketoses, sucrose, fructose, and total reducing sugars, with glucose being determined by calculation. A series of acid phosphatase assays were conducted using as substrates the following compounds: ß-glycerophosphate, adenosinetriphosphate, uridine diphosphate glucose, glucose-1-phosphate, glucose-6-phosphate, fructose-6- phosphate, fructose-1,6-diphosphate, and 3-phosphoglyceric acid. Additional enzymes included invertase, amylase, hexokinase, phosphohexose isomerase, aldolase, triosephosphate dehydrogenase, phosphoglyceryl kinase, condensing enzyme, isocitric acid dehydrogenase, transaminase, peroxidase, and glucose oxidase. All enzyme preparations consisted of dialyzed water-soluble protein extracted from freeze-dried leaf tissue and precipitated with ammonium sulfate between 35 and 95 percent of saturation.

scholarly journals Paenibacillus curdlanolyticus Strain B-6 Xylanolytic-Cellulolytic Enzyme System That Degrades Insoluble Polysaccharides

2006 ◽  
Vol 72 (4) ◽  
pp. 2483-2490 ◽  
Author(s):  
Patthra Pason ◽  
Khin Lay Kyu ◽  
Khanok Ratanakhanokchai
Keyword(s):  
Growth Phase ◽  
Enzyme Preparation ◽  
Enzyme System ◽  
Crude Enzyme ◽  
Cellulolytic Enzyme ◽  
Crude Enzyme Preparation ◽  
Multienzyme Complexes ◽  
Sds Page ◽  
Paenibacillus Curdlanolyticus ◽  
Cellulose Binding

ABSTRACT A facultatively anaerobic bacterium, Paenibacillus curdlanolyticus B-6, isolated from an anaerobic digester produces an extracellular xylanolytic-cellulolytic enzyme system containing xylanase, β-xylosidase, arabinofuranosidase, acetyl esterase, mannanase, carboxymethyl cellulase (CMCase), avicelase, cellobiohydrolase, β-glucosidase, amylase, and chitinase when grown on xylan under aerobic conditions. During growth on xylan, the bacterial cells were found to adhere to xylan from the early exponential growth phase to the late stationary growth phase. Scanning electron microscopic analysis revealed the adhesion of cells to xylan. The crude enzyme preparation was found to be capable of binding to insoluble xylan and Avicel. The xylanolytic-cellulolytic enzyme system efficiently hydrolyzed insoluble xylan, Avicel, and corn hulls to soluble sugars that were exclusively xylose and glucose. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of a crude enzyme preparation exhibited at least 17 proteins, and zymograms revealed multiple xylanases and cellulases containing 12 xylanases and 9 CMCases. The cellulose-binding proteins, which are mainly in a multienzyme complex, were isolated from the crude enzyme preparation by affinity purification on cellulose. This showed nine proteins by SDS-PAGE and eight xylanases and six CMCases on zymograms. Sephacryl S-300 gel filtration showed that the cellulose-binding proteins consisted of two multienzyme complexes with molecular masses of 1,450 and 400 kDa. The results indicated that the xylanolytic-cellulolytic enzyme system of this bacterium exists as multienzyme complexes.

scholarly journals Probing the promiscuity of ent-kaurene oxidases via combinatorial biosynthesis

2016 ◽  
Vol 113 (9) ◽  
pp. 2526-2531 ◽  
Author(s):  
Sibongile Mafu ◽  
Meirong Jia ◽  
Jiachen Zi ◽  
Dana Morrone ◽  
Yisheng Wu ◽  
...  
Keyword(s):  
Natural Products ◽  
Metabolic Engineering ◽  
Substrate Specificity ◽  
Plant Hormone ◽  
Structural Similarity ◽  
Combinatorial Biosynthesis ◽  
Underlying Structure ◽  
Engineering System ◽  
Insight Into

The substrate specificity of enzymes from natural products’ metabolism is a topic of considerable interest, with potential biotechnological use implicit in the discovery of promiscuous enzymes. However, such studies are often limited by the availability of substrates and authentic standards for identification of the resulting products. Here, a modular metabolic engineering system is used in a combinatorial biosynthetic approach toward alleviating this restriction. In particular, for studies of the multiply reactive cytochrome P450, ent-kaurene oxidase (KO), which is involved in production of the diterpenoid plant hormone gibberellin. Many, but not all, plants make a variety of related diterpenes, whose structural similarity to ent-kaurene makes them potential substrates for KO. Use of combinatorial biosynthesis enabled analysis of more than 20 such potential substrates, as well as structural characterization of 12 resulting unknown products, providing some insight into the underlying structure–function relationships. These results highlight the utility of this approach for investigating the substrate specificity of enzymes from complex natural products’ biosynthesis.

Determination of Plant Hormone Indole-3-Acetic Acid in Aqueous Solution

2012 ◽  
Vol 25 (1) ◽  
pp. 303-307 ◽  
Author(s):  
Jana Bulíčková ◽  
Romana Sokolová ◽  
Stefania Giannarelli ◽  
Beatrice Muscatello
Keyword(s):  
Aqueous Solution ◽  
Acetic Acid ◽  
Plant Hormone ◽  
Indole 3 Acetic Acid

Identification of IAA-regulated genes in Pseudomonas syringae pv. tomato strain DC3000

2021 ◽  
Author(s):  
Arnaud-Thierry Djami-Tchatchou ◽  
Zipeng Alex Li ◽  
Paul Stodghill ◽  
Melanie J. Filiatrault ◽  
Barbara N. Kunkel
Keyword(s):  
Gene Expression ◽  
Arabidopsis Thaliana ◽  
Acetic Acid ◽  
Stress Response ◽  
Pseudomonas Syringae ◽  
Plant Pathogen ◽  
Type Iii Secretion ◽  
Plant Hormone ◽  
Indole 3 Acetic Acid ◽  
Exogenous Iaa

The auxin indole-3-acetic acid (IAA) is a plant hormone that not only regulates plant growth and development but also plays important roles in plant-microbe interactions. We previously reported that IAA alters expression of several virulence-related genes in the plant pathogen Pseudomonas syringae pv. tomato strain DC3000 ( Pto DC3000). To learn more about the impact of IAA on regulation of Pto DC3000 gene expression we performed a global transcriptomic analysis of bacteria grown in culture, in the presence or absence of exogenous IAA. We observed that IAA repressed expression of genes involved in the Type III secretion (T3S) system and motility and promoted expression of several known and putative transcriptional regulators. Several of these regulators are orthologs of factors known to regulate stress responses and accordingly expression of several stress response-related genes was also upregulated by IAA. Similar trends in expression for several genes were also observed by RT-qPCR. Using an Arabidopsis thaliana auxin receptor mutant that accumulates elevated auxin, we found that many of the P. syringae genes regulated by IAA in vitro were also regulated by auxin in planta . Collectively the data indicate that IAA modulates many aspects of Pto DC3000 biology, presumably to promote both virulence and survival under stressful conditions, including those encountered in or on plant leaves. IMPORTANCE Indole-3-acetic acid (IAA), a form of the plant hormone auxin, is used by many plant-associated bacteria as a cue to sense the plant environment. Previously, we showed that IAA can promote disease in interactions between the plant pathogen Pseudomonas syringae strain Pto DC000 and one of its hosts, Arabidopsis thaliana . However, the mechanisms by which IAA impacts the biology of Pto DC3000 and promotes disease are not well understood. Here we demonstrate that IAA is a signal molecule that regulates gene expression in Pto DC3000. The presence of exogenous IAA affects expression of over 700 genes in the bacteria, including genes involved in Type III secretion and genes involved in stress response. This work offers insight into the roles of auxin promoting pathogenesis.

scholarly journals Callogenesis in Cicer arietinum and identification of a genotype resistant to Ascochyta rabiei

2020 ◽  
Vol 12 (3) ◽  
pp. 673-682
Author(s):  
Yasmina BENABDESSLEM ◽  
Kadda HACHEM ◽  
Samia GHOMARI
Keyword(s):  
Cicer Arietinum ◽  
Crop Yields ◽  
High Sensitivity ◽  
Ascochyta Rabiei ◽  
Dichlorophenoxyacetic Acid ◽  
Ms Medium ◽  
Fruiting Bodies ◽  
Callus Tissues ◽  
2,4 Dichlorophenoxyacetic Acid ◽  
Indole 3 Acetic Acid

The chickpea (Cicer arietinum) is one of the leguminous species most appreciated by consumers in the Mediterranean basin, while being an important source of protein. Nevertheless, its crop yields are greatly limited by several biotic and abiotic stresses, the main one being Ascochyta rabiei, the causal agent of anthracnose. As traditional breeding methods have proved to be ineffective in controlling this pathogen, resorting to biotechnological methods is necessary. Therefore, in this study, the callogenic capacity of stem and leaflet explants from three genotypes of chickpea, namely ‘FLIP 84-92 C’, ‘ILC 32-97’, and ‘ILC 263’, cultured on Murashige and Skoog (MS) medium with different hormonal balances of auxins (indole-3-acetic acid [IAA] and 2,4-dichlorophenoxyacetic acid [2,4-D]) and cytokinin (kinetin), was determined. For all the genotypes, high percentages of callogenesis were recorded in the different explants grown on an MS medium with 2 mg of both IAA and kinetin. Then, a patho-system of Cicer arietinum calluses with Ascochyta rabiei was investigated, followed by a histological assessment of this interaction. The presence of the fruiting bodies of the pathogen was revealed in the calluses of the ‘ILC 32-97’ and ‘ILC 263’ genotypes. Notably, the latter showed a high sensitivity to the pathogen, as indicated by an abundance of pycnidia in its tissues. As for the ‘FLIP 84-92 C’ genotype, the histological sections showed a total absence of inter- and intracellular fruiting bodies of the pathogen in the callus tissues. Therefore, this genotype was considered as resistant to Ascochyta rabiei.

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