On the Mechanism of Action of Growth Regulators

Muir, Robert; Hansch, Corwin

doi:10.1104/pp.28.2.218

Cited by 79 publications

(15 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…One of the most prominent of these theories holds that MH2 acts as a sulfhydryl reagent (7), and more recently it has been suggested that MH acts as a carbonyl reagent (12). The idea that MH might react with sulfhydryl groups was supported by reports that it can inhibit respiration in several plant tissues and can block several sulfhydryl enzymes (13).…”

mentioning

confidence: 63%

Failure of Maleic Hydrazide to Act as a Sulfhydryl or Carbonyl Reagent

Noodén

1973

Plant Physiol.

View full text Add to dashboard Cite

A wide variety of molecular mechanisms have been proposed to explain the actions of the synthetic plant growth regulator maleic hydrazide (3). One of the most prominent of these theories holds that MH2 acts as a sulfhydryl reagent (7), and more recently it has been suggested that MH acts as a carbonyl reagent (12). The idea that MH might react with sulfhydryl groups was supported by reports that it can inhibit respiration in several plant tissues and can block several sulfhydryl enzymes (13). Several subsequent studies, however, mM MH (-U--), 5 mM L-cysteine (-0-), a mixture of MH and cysteine at these concentrations (allowed to stand at 25 C for about 30 min) (--0--), and the sum of the absorption spectra of MH and cysteine taken separately (--0--). All of these solutions and the reference buffer contained 20 mm tris-HCl at pH 7.0. These absorption spectra were measured on a Cary recording spectrophotometer in cells with a 1-cm path length.indicate a lack of effect on both respiration and many sulfhydryl enzymes (1,3,4,10,13). Furthermore, MH does not decrease the number of thiol groups in radish leaf homogenates (13), and attempts to prevent MH from inhibiting root growth with cysteine were unsuccessful (8) UV spectral studies to determine if MH and sulfhydryl or carbonyl compounds interact in such a way as to cause spectral changes. This would be expected if they were linked covalently, because a double bond would probably be lost or at least the distribution valency electrons would be changed (5, 11). (b) Using paper chromatography, a search for possible derivatives formed through reaction with sulfhydryl or carbonyl compounds. Figure 1 shows the UV absorption spectrum for 0.1 mm MH (recrystallized seven times from hot water) in 20 mM tris, pH 7. Maximal absorption occurs at about 328 nm and minimal at about 265 nm. This corresponds well with spectra reported for MH in sodium pyrophosphate buffer at pH 8.4 (6). Figure 1 also demonstrates that a mixture of freshly made 5 mM cysteine (chosen because it is the thiol suspected to react with MH and it is less hindered stericly than cysteine in protein) and 0.1 mm MH in 20 mm tris, pH 7 (selected to approximate a physiological pH) absorbed UV light to the same extent as the sum of the absorbances of the MH and cysteine separately. Similar results were obtained with 0.2 mm MH and 6 mm cysteine. Thus cysteine and MH do not interact in a way which changes their UV absorption. As expected, a similar mixture of 2 mm cysteine and 1 mm iodoacetate, a well known sulfhydryl reagent, undergoes considerable change in UV absorption; relative to the sum of the individual spectra, the mixture absorbs less from about 249 to about 320 nm and more below 249 nm.Pyruvate was selected as the carbonyl compound to test for reaction with MH. because it was used to reverse MH inhibition of monoamine oxidase, a result which led to the suggestion that MH acts as a carbonyl reagent (12). When 5 mM pyruvate and 0.2 mm MH are mixed as above in 20 mM tris, pH 7, the mixture again absorbs UV li...

show abstract

mentioning

confidence: 63%

Failure of Maleic Hydrazide to Act as a Sulfhydryl or Carbonyl Reagent

Noodén

1973

Plant Physiol.

View full text Add to dashboard Cite

show abstract

“…In addition, 2,4,6-Cl 3 -, 2,4,6-Br 3 -, 2,4,6-Me 3 -and 2,4-Cl 2 -6-Me-POAs were inactive as shown in Fig. 1 [7].…”

mentioning

confidence: 87%

“…From 1949 to 1953, Corwin collaborated with Robert Muir, Professor of Botany at University of Iowa, and published five papers [3][4][5][6][7] in which they systematically investigated and analyzed the growth activity of synthetic hormones using a reliable bioassay procedure elaborated by them to measure the stem elongation of oat seedlings [3]. While the 3-Cl-, 4-Cl-, 3-Br-and 4-Br-POAs were about 100 times more potent than POA and about 1/10 less potent than 2,4-D, the 2,4,5-Cl 3 -POA was as active as 2,4-D.…”

mentioning

confidence: 99%

In memoriam Professor Corwin Hansch: birth pangs of QSAR before 1961

Fujita

2011

J Comput Aided Mol Des

View full text Add to dashboard Cite

“…The results obtained with MH treatments are similar to those obtained by Greulach and Atchison (1950), Greulach (1953) and Rossi (1955). Muir and Hansch (1953) and Hughes and Spragg (1958) are of the opinion that MH reacts with the sulfhydryl groups of the protein in the cells . The results with colchicine treatments are also similar to those obtained by Davidson (1964) and Herich (1966).…”

Section: Discussionmentioning

confidence: 99%

Effects of IAA with maleic hydrazide and colchicine on root tip mitosis.

Singh

1982

CYTOLOGIA

View full text Add to dashboard Cite

Mutachromosomic chemicals not only cause structrual changes in the chromo somes but also affect the rate of mitosis (Darlington and McLeish 1951, Bowen and Wilson 1954, Rossi 1955, Kihlman 1956, McManus 1959, Davidson 1964, Prasad and Das 1977. These active chemicals belong to divergent groups and vary in their action. Continuous attempts are being made to discover certain general principles of action among these numerous and divergent chemicals. A fruitful method in this field is to study their comparative effects under similar conditions. This paper reports the results of an experiment designed to study the effects of three chemicals of varying concentration and duration on the mitotic behaviour of Atlium cepa Linn. root tips. While the literature on MH and colchicine is large, work with IAA is still scanty. A comparative study of the effects of IAA with MH and col chicine was thus thought to be fruitful. Materials and methodsThree chemicals namely, maleic hydrazide, MH (an antiauxine), indole-3 acetic acid, IAA (a growth substance) and colchicine (a mitoitc poison) were used for the treatment. The bulbs of Allium cepa Linn. were placed on the mouth of the specimen tubes filled with the aqueous solution of each chemical of 25, 50 and 75 ppm concentrations for 4, 8 and 12 hours and it was ensured that the base and roots of bulbs were dipping in the solution during the treatment. After this treat ment the bulbs were allowed a recovery period of 24 hours in distilled water. The root tips were fixed in 3:1 alcohol-acetic acid and stored in 70per cent alcohol in a refrigerator. For cytological preparations 0.5per cent haematoxylin was used. ResultsThe effects were studied in two groups namely, the effects on mitotic index and the induction of abnormalities in dividing nuclei.The mitotic index and cell metabolism were greatly affected by all the three chemicals.

show abstract

On the Mechanism of Action of Growth Regulators

Cited by 79 publications

References 25 publications

Failure of Maleic Hydrazide to Act as a Sulfhydryl or Carbonyl Reagent

Failure of Maleic Hydrazide to Act as a Sulfhydryl or Carbonyl Reagent

In memoriam Professor Corwin Hansch: birth pangs of QSAR before 1961

Effects of IAA with maleic hydrazide and colchicine on root tip mitosis.

Contact Info

Product

Resources

About