The effect of substituted phenols on the activity of the indoleacetic acid oxidase of peas

Section: Resultsmentioning

confidence: 99%

Pigment Changes Associated with Application of Ethephon ((2-Chloroethyl)phosphonic Acid) to Fig (Ficus carica L.) Fruits

Puech¹,

Rebeiz²,

Crane³

1976

“…The data support the assumption that the enzymatic portion of the indoleacetic acid oxidase system in cotton is a peroxidase. Thimann's observation, sufficient evidence has been accumulated to define the major substance responsible for auxin activity as indole-3-acetic acid and to attribute the destruction of IAA within the plant, primarily, to a peroxidase-based enzyme system generally known as IAA-oxidase (11,15,20,28,34,37). By virtue of its role in limiting the supply of IAA within the plant, the IAA-oxidase system has been recognized as a plant growth regulatory mechanism.…”

mentioning

confidence: 99%

The Relationship of the Peroxidative Indoleacetic Acid Oxidase System to in Vivo Ethylene Synthesis in Cotton

Fowler

Morgan

1972

Since peroxidase and manganese have been implicated in both auxin destruction and ethylene production, the effect of auxins and high tissue levels of manganese on the peroxidative indoleacetic acid oxidase system and the internal level of ethylene was determined in cotton (Gossypium hirsutum L.cv. Watson GL-7). The highest level of manganese tested produced manganese toxicity symptoms, including necrotic lesions, accompanied by an increase in internal ethylene levels at about 15 days after treatment initiation. Statistically significant increases in indoleacetic acid oxidase and peroxidase activity were first observed 2 days later and were paralleled by tissue manganese levels above 7.4 milligrams per gram dry weight and internal ethylene levels of 0.77 microliters per liter air. Eight hours after application of 2,4-dichlorophenoxyacetic acid or indoleacetic acid, the internal levels of ethylene were increased to above 6.6 microliters per liter air in cotton plants, and levels of this magnitude were maintained for a 72-hour period of observation. Modification of peroxidase and indoleacetic acid oxidase activity in auxintreated plants definitely occurred well after the elevation of internal ethylene levels. While ethylene levels and indoleacetic acid oxidase activity were increased by both experimental approaches, the earlier appearance of increased ethylene indicates that the peroxidative indoleacetic acid oxidase system in cotton is not involved in ethylene synthesis or that this enzyme is not the rate-limiting factor when ethylene synthesis is increased. Ethylene, as well as auxin destruction, may be involved in some of the long term plant responses to toxic levels of manganese. The findings also suggest that auxin-induced ethylene may play a role in the elevation of peroxidase and indoleacetic acid oxidase activity eventually seen in extracts of plants treated with auxins. The data support the assumption that the enzymatic portion of the indoleacetic acid oxidase system in cotton is a peroxidase. Thimann's observation, sufficient evidence has been accumulated to define the major substance responsible for auxin activity as indole-3-acetic acid and to attribute the destruction of IAA within the plant, primarily, to a peroxidase-based enzyme system generally known as IAA-oxidase (11,15,20,28,34,37). By virtue of its role in limiting the supply of IAA within the plant, the IAA-oxidase system has been recognized as a plant growth regulatory mechanism.The potential role of the IAA-oxidase system as a plant growth regulatory mechanism assumed new dimensions with Yang's (39) discovery that an enzyme system strikingly similar to the peroxidative IAA-oxidase system is capable of synthesizing the plant hormone ethylene. If this ethylene-synthesizing system functions in vivo, the growth regulatory activities of the peroxidative IAA-oxidase system may encompass those areas in which ethylene is involved as well as the growth phenomena associated with IAA. This additional regulatory role for peroxidases is supported...

“…These data support our hypothesis that the growth-promoting effect of catecholamines is due to their inhibition of IAA degradation, resulting in higher levels of auxin. Dihydroxyphenols have been known for over three decades to inhibit IAA oxidation (15,20), and compounds that share these characteristics with catecholamines are active in the TCL system. When caffeic and chlorogenic acid (25 gM) were added to tobacco TCLs, they stimulated ethylene production and growth at levels comparable to dopamine (C.M.…”

Section: Possible Mechanism Of Actionmentioning

confidence: 99%

Growth Stimulation by Catecholamines in Plant Tissue/Organ Cultures

Protacio¹,

Dai²,

Lewis³

et al. 1992

Addition of catecholamines at micromolar concentrations caused a dramatic stimulation of growth of tobacco (Nicotiana tabacum) thin cell layers (TCLs) and Acmella oppostHffolia "hairy" root cultures. A threefold increase in the rate of ethylene evolution was observed in the catecholamine-treated explants. Aminooxyacetic acid and silver thiosulfate, inhibitors of ethylene biosynthesis and action, respectively, reduced the growth-promoting effect of dopamine. However, these compounds alone could also inhibit the growth of the TCL explants. The catecholamines dopamine, norepinephrine, and epinephrine and their precursors phenylethylamine and tyramine ( Fig. 1)