IAA-oxidase Activity Research Articles

Peroxidase, indoleacetic acid oxidase, and amylase activity in necrotic wheat hybrid and its parents

At the seedling stage, growth pattern and changes in the activity of enzymes were studied in "necrotic" hybrid of wheat (Triticum aestivum) and its parents HI 617 (female) and HD 2160 (male). Growth of the hybrid is less when compared with either parent in light as well as in dark. In dark the hybrid shows higher activity of amylase, peroxidase, and indoleacetic acid oxidase than either parent. In light, however, the activity of peroxidase and amylase is intermediate between the two parents in the axis and root and higher than the parents in the endosperm of the hybrid. It appears that light modulates gene activity of the hybrid and in light the male-parent gene is dominant.

HORMONAL REGULATION OF EPIPHYLLOUS BUD RELEASE AND DEVELOPMENT IN BRYOPHYLLUM CALYCINUM

The effects of various concentrations of several auxins and cytokinins separately and in combination on epiphyllous budding of Bryophyllum calycinum were investigated, using a marginal leaf strip method. The number of buds released per leaf in 10−6 m benzyladenine (BA) was 2.8 times greater than those in water, and 1.6 times greater in 10−5 m isopentyladenine (IPA). BA, IPA and kinetin were antagonistic to indoleacetic acid (IAA) or naphthaleneacetic acid (NAA) when used in combination treatments. The IAA oxidase co‐factor p‐coumaric acid (PCA) increased the number of epiphyllous buds to twice that of the water controls. This stimulatory effect of PCA on bud release suggests that an increase in IAA oxidase activity may be one of the significant changes that precedes the release of epiphyllous buds.

Cherry Fruit Growth: Localization of Indoleacetic Acid Oxidase and Inhibitors in the Seed

Abstract The distribution of indoleacetic acid (IAA) oxidase activity was determined in seeds of sour cherry (Prunus cerasus L. cv. Montmorency) fruits in mid-Stage II of development, 32 days after full bloom. The greatest activity was found in the integument tissue. No IAA oxidase activity was detected in the embryo or endosperm. When polyvinylpolypyrrolidone (PVP) was added to the extraction buffer (0.2 m acetate, pH 4.0), a trace of activity was detected in the embryo, but not in the endosperm. Inhibitors of IAA oxidase were coextracted with the enzyme and occurred in the greatest quantity in the integument tissue, an intermediate level in the embryo, and only a trace in the endosperm. The inhibitor from the integument and embryo tissues exhibited different kinetics when increasing concentrations were assayed against IAA oxidase isolated from the integuments. The possible significance of IAA oxidase and inhibitor distribution in the seed is discussed in relation to sour cherry fruit growth.

Cherry Fruit Development: Changes in Seed IAA Oxidase Activity

Abstract Indoleacetic acid (IAA) oxidase activity was measured in seeds of Prunus cerasus L. cv. Montmorency from full bloom to maturity. IAA oxidase activity reached a maximum at early Stage II of fruit development and decreased to trace levels during Stage III. The peak of IAA oxidase activity coincided with the time that the seed approached full size and endosperm was at a maximum volume and just prior to the rapid growth phase of the embryo. Inhibitors of IAA oxidase were coextracted (acetate buffer, 0.2 m, pH 4.0) with the enzyme. Low molecular weight compounds, which modified IAA oxidase activity, were separated from the enzyme extract with Sephadex G-25. The compounds from seeds of fruits in Stages I and III inhibited and from Stage II enhanced IAA oxidase activity. The possible role of IAA oxidase and the effectors in cherry fruit development are discussed.

Activity of IAA oxidase, catalase and amylase in morphactin-induced malformations of mango inflorescences

Three types of mango inflorescence, viz. healthy (H), naturally malformed (N) and morphactin-induced malformed (M), of ‘Dashehari’, ‘Mallika’, ‘Benazir’ and ‘Taimuria’ cultivars were studied. Morphactin (500 mg 1 −1) treatment drastically reduced the growth as well as the fresh weight of the panicles. IAA oxidase activity was significantly different in the 3 types of panicle, and ranged from 6.5 μmoles IAA/g tissue/h in ‘Taimuria’ to 39.4 in ‘Benazir’ for H, while it was from 25.5 in ‘Taimuria’ to 51.0 in ‘Mallika’ for N. However, for M it was more than double that for H. Catalase activity was the lowest for M followed by N and then H. Amylase activity did not exhibit any definite trend. The IAA oxidase had a significant negative correlation with catalase and growth parameters. The increase in the activity of IAA oxidase by morphactin treatment, which caused malformation-like symptoms, and the observed high activity of the enzyme in naturally malformed panicles suggest that malformation might be due to decreased levels of auxins or to hormonal imbalance.

Peroxidase and IAA-oxidase in crude and partially purified enzyme extracts of growing and differentiating root cells

Crude enzyme extracts from the zones of division, elongation and differentiation of cells of primary maize (Zea mays) root show peroxidase activity but lack IAA-oxidase activity. After partial purification of the extracts by gel filtration on Sephadex G-25, the specific peroxidase activity increases almost twice and a high IAA-oxidase activity appears.

Coconut peroxidase isoenzymes: isolation, partial purification and physicochemical properties

Peroxidases (donor: hydrogen peroxide oxidoreductase; EC 1.11.1.7) from normal and mutant (makapuno) coconut endosperms were compared in terms of their specific activities and isoenzyme patterns, physicochemical properties and ability to oxidize IAA. Makapuno peroxidases have significantly higher activity during the early stages of development and significantly lower activity at maturity when compared with the normal. Six anodic isoenzymes were detected at pH 8.9 from both sources by polyacrylamide gel electrophoresis. Both normal and makapuno crude peroxidases have optimum activity at pH 5.5 and are thermostable over a wide range of temperature. The V max was obtained at 1 × 10 −2 M hydrogen peroxide while the apparent K m was at ca 1 × 10 −3 M hydrogen peroxide. In general, no marked difference was noted between the physicochemical properties of peroxidases from both sources. Isolation and partial purification of the isoenzymes were performed by conventional methods including ammonium sulfate fractionation, DEAE Sephadex A-50 ion exchange chromatography and Sephadex G-200 gel filtration. Peroxidase activity was localized in the 50–95% ammonium sulfate precipitate. Gel filtration resolved three protein peaks with peroxidase (Px) activity, the electrophoretic mobilities of which corresponded to Px3, Px4 and Px5. Px5 was purified 17 600-fold and found to be a tetramer with a native MW of 196000 and a subunit MW of 55000. Px3 and Px4 were monomers with MWs of 36300 and 46800, respectively. IAA oxidase activity was detected in the partially purified peroxidases from developing normal endosperms but not from mature endosperms.

A rapid method for determining urinary indoleacetic acid concentration and its clinical significance as the tumor-marker in the diagnosis of malignant diseases

A rapid method for determining urinary indole-3-acetic acid (IAA) is introduced as the tumor-marker for the screening and diagnostic purpose of cancer patients by means of high performance liquid chromatography (HPLC). Its clinical significance is discussed along with a review of literatures. The IAA concentration and creatinine level of optionally collected urine samples were measured and used for the calculation of IAA amount per unit creatinine (microgram IAA/mg creatinine) in urine. Thus, an amount of 24-hours urinary IAA could be calculated without collecting a whole day's urine supply. Analysis of urinary IAA was performed within 10 minutes by HPLC. Urinary IAA level is usually high in the patients with the upper G-I tract cancers such as gastric cancer, esophageal cancer and hepato-biliary tract cancer, and also malignant hematopoietic disorders. But it is also high in non-cancer patients such as liver cirrhosis, diabetes mellitus and cholelithiasis occasionally. The patients with high urinary IAA level also showed high urinary levels of 5-hydroxy indoleacetic acid (5-HIAA) and monoamine oxidase activity (MAO). It was characteristic that hepatocellular carcinoma showed slight elevation of urinary IAA with normal levels of 5-HIAA and MAO. It is conclusive that the positive rate of elevated urinary IAA level was high in the patients with gastric cancer with ulcer-forming type in its morphological classification, and its level tends to elevate as the disease progresses. Therefore, the measurement of urinary IAA level in an optionally collected urine sample, as the tumor-marker, can be useful to check the progression and regression of gastric cancer.

An ethylene-forming enzyme in Citrus unshiu fruits

An ethylene-forming enzyme from Citrus unshiu fruits was purified some 630-fold. The enzyme catalysed ethylene formation from 1-aminocyclopropane-1-carboxylic acid in the presence of pyridoxal phosphate, β-indoleacetic acid, Mn 2+ and 2,4-dichlorophenol. It behaved as a protein of MW 40 000 on Sephacryl S-200 gel filtration, and gave one band corresponding to a MW of 25 000 on SDS-PAGE. It had a specific activity of 0.025 μmol/min·mg protein. It exhibited IAA oxidase activity and had no guaiacol peroxidase or NADH oxidase activity. Its K m for ACC was 2.8 mM, and its pH optimum was 5.7. It was inhibited by potassium cyanide n-propyl gallate and Tiron. d-Mannose, histidine, iodoacetate, PCMB, dimethylfuran and superoxide dismutase showed no inhibition. β-Indoleacrylic acid against IAA competitively inhibited ethylene formation. Other IAA analogues, such as β-indolepropionic acid, β-indolecarboxylic acid and β-indolebutylic acid, slightly stimulated ethylene formation. β-Indoleacrylic acid against 1-aminocyclopropane-1-carboxylic acid non-competitively inhibited ethylene formation. Ascorbate was a potent inhibitor. The inhibitory effects, however, were not always reproduced in vivo. It is difficult to identify this enzyme system as a natural in vivo system from the above observations. Nevertheless, the possible in vivo participation of this in vitro enzyme system is discussed.

Ascorbic acid as negative effector of the peroxidase‐catalyzed degradation of indole‐3‐acetic acid

Ascorbic acid is a strong inhibitor of indole‐3‐acetic oxidation catalyzed by commercial horse‐radish peroxidase. In the presence of excess ascorbic acid, the indole‐acetic acid oxidation catalysis is apparently blocked. The activity of peroxidase for indoleacetic acid at pH 3.7 and 33°C, in the presence of 2,4‐dichlorophenol and MnCl2 as promotors was measured by polarographic technique. The Km was 0.27 mM and the maximum velocity was 1.02 mmol O2 (mg protein)−1 min−1. Dixon plots lead to an apparent Ki of 1.25 (μM for ascorbic acid and the inhibition was apparently competitive. Ascorbic acid, besides appearing to be a strong inhibitor of the IAA oxidase activity of peroxidase, seemed to protect IAA from total degradation. Addition of more than 5 μM ascorbic acid produced both an exponential increase in the lag time before the onset of reaction and, at the end, an oxidation protection of 26 μM IAA when 111 μM IAA was present at the stawrt. The possibility of ascorbic acid‐IAA auxin from endogenous oxidation in plants, is proposed.

Physiological and biochemical changes associated with cotton fibre development. II. Auxin oxidising system

Changes in IAA oxidase, and in cytoplasmic and ionically wall‐bound peroxidase activities were studied in the developing fibres of three cotton cultivars (Gossypium hirsutum L. cv. Gujarat‐67, cv. Khandwa‐2 and G. herbaceum L. cv. Digvijay), designated as long, medium and short staple cultivars, respectively. In all the three cultivars IAA oxidase activity was low during the fibre elongation phase, while the activity increased significantly during the secondary thickening phase. The increase in IAA oxidase activity in the three cultivars showed close correspondence with their respective total period of elongation. No relationship between cytoplasmic peroxidase activity and fibre development was discernible. The ionically bound wall peroxidase activity, however, recorded low levels during the elongation phase and higher levels during the secondary thickening phase. The role of wall peroxidase in cessation of elongation growth is discussed.

Toxic action of barium chloride on germination, growth and metabolism of rice ( Oryza sativa L.)

The effects of barium chloride on growth and metabolism of rice ( Oryza sativa L.) seedlings are noted. Inhibition of seedling elongation began at 0.1 mM. Root growth inhibition was more pronounced than shoot growth inhibition. Germination declined at 1 mM and was completely eliminated at 100 mM. Ba-induced elongation inhibition could be totally reversed with transfer to GA 3; partial recovery occurred with IAA, EDTA, cations (K, Ca and Fe) and malate, whereas others were ineffective. Respiration rates were found to decline and were proportional to inhibition of seedling vigor. Coincident with growth inhibition, was a difference in the pattern of distribution of sugar and nitrogen in the embryo and the endosperm. As compared to control, there was a predominance of reducing sugar and soluble nitrogen in Ba-soaked embryos. Activities of peroxidase, IAA oxidase and ascorbic acid oxidase on a seedling basis were diminished by Ba treatments; catalase was unaffected. On a dry weight basis, however, considerable stimulation was observed in catalase and ascorbic acid oxidase activities.

Stimulation of Root Formation onImpatiens balsamina L. cuttings by coumarin and the associated biochemical changes

Coumarin-caused stimulation of rooting of cuttings ofImpatiens balsamina L. is associated with an increase in the endogenous contents of carbohydrates, total phenols and proteins. Peroxidase, IAA oxidase and polyphenol oxidase activities also increased in coumarin treated cuttings at the time of cell division preceding primordia formation (6–12 h after treatment). Coumarin effect on rooting as well as on related biochemical changes resembles the effect of auxins in some ways.

Changes in Indoleacetic Acid Oxidase and Peroxidase Activities During Cotton Fibre Development

Summary Growth analysis, IAA oxidase and both cytoplasmic and ionically bound wall peroxidase activities were investigated during the entire period of cotton fibre development. IAA oxidase and peroxidase activities recorded low levels during the elongation phase while during the secondary thickening phase these activities increased significantly. It is suggested that IAA oxidase in vivo may regulate the levels of IAA. The close correlation between cessation of elongation growth and increase in wall peroxidase points to an important role of this enzyme in the termination of the elongation phase. Its role as a wall rigidifying factor is discussed. Electrophoresis data supported the view that both IAA oxidase and peroxidase activities are associated with a single protein molecule.

IAA Oxidase Activity in Relation to IAA Effects on Rooting Stem Cuttings

Summary Stem cuttings of S. tetrasperma and P. robusta rooted profusely and also exhibited high IAA oxidase activity prior to root formation, while those of H. rosa-sinensis rooted poorly and exhibited poor IAA oxidase activity. The cuttings of E. citriodora which did not root at all failed to exhibit IAA oxidase activity. Treatment of cuttings with IAA also affected the rooting as well as IAA oxidase activity differentially. Thus, IAA increased both rooting as well as IAA oxidase activity of the cuttings of S. tetrasperma and P. robusta ., had only slight effect on cuttings of H. rosa-sinensis and not at all on those of E. citriodora. The cuttings of E. citriodora showed the presence of some inhibitors which inhibited in vitro IAA oxidase activity of P. robusta . The possibility of involvement of IAA oxidase in the process of IAA effects on root formation on stem cuttings has been discussed.

Indoleacetic acid oxidase activity in main stem homogenates of flax genotrophs and genotypes

The IAA-oxidase and peroxidase capabilities along the length of the main stem tissues of two flax genotrophs L and S and two flax genotypes R and M were examined in vitro. Stem gradients for peroxidase activity increased basipetally in all plant types, as did IAA-oxidase activity gradients at non-rate-limiting concentrations of Mn 2+. Correlations between peroxidase activity and non-rate-limited IAA-oxidase activity supported the contention of dual activities on the same molecule. At rate-limiting concentrations of Mn 2+, IAA-oxidase activity did not correlate with peroxidase activity. Plant type differences were detected in rate-limited IAA-oxidase activity. This activity was higher in the stem region immediately above the cotyledons (axillary buds) of the more branched types, L and R, than in the sparsely branched types, S and M.

Association of Auxin Protectors, Peroxidase, Indoleacetic Acid Oxidase and Polyphenol Oxidase in Zizyphus Gall and Normal Stem Tissues Grown in Culture

Summary Zizyphus normal stem tissue extract destroyed IAA when the two were incubated together. On the other hand, with gall tissue extract, IAA destruction occurred only following a lag period which was induced by auxin protectors detected in the gall tissue. The in vivo gall tissue showed no peroxidase and little IAA-oxidase activity for the incubation period tested. Polyphenol oxidase activity and total and O-dihydroxyphenols increased with the growth of the gall up to the 30th day. The protector-induced lag in IAA destruction was decreased when higher concentrations of IAA were used in the reaction mixture. Both normal and gall tissues were exposed to effectors such as NAA, IAA, 2,4-D, DL-tryptophan, gibberellic acid, and cycloheximide, each added separately. A differential response of normal and gall tissues to the different growth regulators in terms of activities of peroxidase, IAA oxidase and polyphenol oxidase was esthablishcd. A general tendency towards a decrease in polyphenol oxidase and an increase in peroxidase and IAA oxidase activities was observed in gall tissue. Both in vivo and in vitro gall tissue showed a higher protein content as compared to normal tissue.

Changes in Soluble and Bound Peroxidase—IAA Oxidase During Tomato Fruit Development

ABSTRACTSoluble peroxidase activity increased dramatically during the early stages of tomato fruit development, reaching a maximum at the mature‐green stage. Ionically and covalently bound peroxidases were also observed, and the activities of these fractions increased steadily throughout fruit development. IAA (indoleacetic acid) oxidase activity was observed in both soluble and bound fractions and paralleled the peroxidase activity. Tissue homogenates from juvenile fruit caused an extended induction period in IAA oxidation reactions catalyzed by the purified tomato fruit peroxidase, suggesting the occurence of a high concentration of phenolic‐type auxin protectors in this tissue. As the fruit developed, tissue homogenates showed a reduction in the amount of auxin protectors as the IAA oxidizing capacity of the fruit increased.

IAA oxidase activity in relation to adventitious root formation on stem cuttings of some forest tree species

IAA oxixase activity was very high in stem cuttings ofSalix tetrasperma andPopulus robusta, which rooted profusely, less in stem cuttings ofHibiscus rosa sinensis which rooted less, and insignificant in those ofEucalyptus citriodora which did not root at all. Protein(s) extracted from the stem cuttings ofE. citriodora inhibited the activity of IAA oxidase as well as root formation on hypocotyl cuttings ofPhaseolus mungo. The possibility of involvement of IAA oxidase activity in the process of adventitious root formation is discussed.

Subcellular Localization of IAA Oxidase in Peas

Indoleacetic acid (IAA) oxidase has been reported to be involved in plant growth because of its alleged role in the control of endogenous IAA levels. This purported role was reevaluated in terms of the properties and subcellular location of the enzyme in etiolated pea (Pisum sativum L. var. Alaska) epicotyls.The enzymic properties of IAA oxidase in the floating pea epicotyl segments are similar to those previously reported in the literature. Other experiments indicate that approximately 70% of the activity is at the cut surfaces of the tissue. In addition, up to 50% of the IAA oxidase activity could be pelleted in a membranous fraction when the released enzyme was centrifuged at 10,000(g). Higher centrifugal forces reduced the proportion of the enzyme in the pellet, suggesting that vesicles containing IAA oxidase rupture at these forces.Subcellular localization of IAA oxidase was accomplished by use of sucrose density gradient centrifugation and fractionation. It was found that the enzyme is associated most closely with Golgi and also to a lesser degree with the lysosomes and endoplasmic reticulum. It is suggested that little if any IAA oxidase is freely soluble in the cytoplasm and is therefore unlikely to have a role in controlling normal growth via IAA levels. The enzyme may, however, have a role in diseased or damaged tissue.