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perennial plants like mugwort. Herbicides that inhibit amino acid formation in plants and those which mimic indole-3-acetic acid are usually systemic in nature, and therefore, multiple herbicides in these classes of chemistry often have some activity on

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D ). Fig. 1. Localization of indole-3-acetic acid (IAA) at the top of Fargesia yunnanensis shoots. ( A ) Immunohistochemical localization at the shoot tip, showing the strong IAA signal in the apical meristem (black arrow), sheath primordia (white

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The relationship between auxin and adventitious root formation has been studied for many years. Indole-3-acetic acid plays a central role in adventitious rooting and was the first plant hormone used to stimulate the rooting of cuttings ( Cooper

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) differentiation stages; SAM = shoot apical meristem; sq = squama; VB = vascular bundle; lp = leaf primordial; ( A–F ) bar = 100 μm, ( G ) bar = 200 μm. Indole-3-acetic acid immunohistochemical localization. Excised samples were immediately fixed in a 2% (w

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·ha −1 acid equivalent) or Myrothecium verucaria alone controlled trumpetcreeper 45% and 30%, respectively ( Boyette et al., 2008 ). Bradley et al. (2003) reported that reduced rates of two mimics of indole-3-acetic acid, dicamba (280 g·ha −1 ) and 2

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Abstract

An indole-3-acetic acid oxidase system was detected and characterized in extracts of immature peach seed (Prunus persica (L) Batsch, cv. Redhaven). The enzyme had a pH optimum of 4.5 to 5.0 and required Mn2+ and 2,4-dichlorophenol for optimum activity. The reaction product appeared to be 3-methyleneoxindole. Catechin, a natural polyphenol, was isolated from peach seed. It inhibited the IAA oxidase system and had a synergistic effect on IAA activity in the Avena coleoptile straight growth assay. Kinetic studies demonstrated that the catechin inhibition was non-competitive with substrate.

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gratefully acknowledged. For discussions that resulted in this work and for their advice on the manuscript, the author thanks Janet P. Slovin and James R. Dunlap. Indole-3-acetyl-1- 0 -β-D-glucose and 4-Cl-IAA were from D. Keglevic and V. Magnus, respectively

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Abstract

Changes in the levels of putative free and conjugated indole-3-acetic acid (IAA) were examined by high performance liquid chromatography (HPLC) during the first 96 hr of adventitious root formation in mung bean [Vigna radiata (L.) R. Wilcz. ‘Berken’] stem cuttings. The putative IAA was characterized as biologically and chemically similar to IAA; ester- and amide-conjugated IAA also were found. Amide-conjugated IAA was an order of magnitude more abundant than either free or ester-conjugated IAA, both of which were present at low levels. In duplicate experiments, the relative levels of free and conjugated IAA in the rooting region fluctuated similarly during root formation, although some differences in timing and magnitude were observed.

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The gravity-sensing mechanism in plants end transduction of the gravity stimulus to re-orientating plant growth has not been ascertained. By removing the everpresent influence of the 1 g terrestrial environment on plant growth and development, information maybe obtained about the gravity detection mechanism in plants. The Space Life sciences Payloads Office at NASA-ARC processed the secondary Payloads flight experiment “Growth Hormone Concentration and Distribution in Plants” (GHCD). The experiment occupied two middeck lockers in the crew compartment onboard the space shuttle Atlantis (STS-34) in October 1989. The payload's Principal Investigator was Dr. S. Bandurski, Professor of Botany at Michigan State University. dr. Bandurski's experiment was designed to investigate concentration, distribution, and turnover rates of indole-3 acetic acid (IAA) in dark-grown corn seedlings exposed to the microgravity environment. The flight data may provide valuable information for long-term crop production in space as well as terrestrial agriculture. This poster will present the flight payload processing procedures necessary to successfully conduct a space shuttle flight experiment.

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Endogenous concentrations of IAA and ABA in the peel, pulp, seed, and abscission zone of mature `Valencia' oranges [Citrus sinesis (L.) Osbeck] were determined by high-performance liquid chromatography and enzyme-linked immunosorbent assay from early November 1998 to mid-June 1999. Ethylene production of mature `Valencia' oranges during the same period was determined by gas chromatography. IAA concentrations in the pulp and seed were three to five times lower than those in the peel over the 7-month observation period. IAA concentration in the abscission zone and peel was high from late April to mid-May, the period of less responsiveness to abscission chemicals. ABA concentration in the pulp was low over the entire observation period. ABA concentration in the abscission zone and peel was low during the less responsive period. Ethylene production was always low except for a slight increase during late December and early February. The IAA to ABA ratio was high in the fruit abscission zone during the less responsive period. Fruit detachment force of CMN-pyrazole-treated fruit was positively correlated with the ratio of endogenous IAA to ABA or endogenous IAA, but negatively to endogenous ABA in the fruit abscission zone. These data suggest the balance between IAA and ABA in the fruit abscission zone may be an important factor in determining sensitivity and thereby the response of mature `Valencia' orange fruit to abscission chemicals. Chemical names used: abscisic acid (ABA); indole-3-acetic acid (IAA); 5-chloro-3-methyl-4-nitro-1H-pyrazole (CMN-pyrazole).

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