Kinetin‐like Activity in Root Exudate of Water‐stressed Sunflower Plants

Itai, Chanan; Vaadia, Yoash

doi:10.1111/j.1399-3054.1965.tb06991.x

Cited by 209 publications

(64 citation statements)

References 12 publications

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“…Plant Mol Biol inexsd prehydrt evdleaveiscnistacelerithatnedg (Fig.7) rgRep 6: [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] The present evidence is consistent with a negative regula- …”

Section: Ba (Rm)supporting

confidence: 76%

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Regulation of Phosphoenolpyruvate Carboxylase and Crassulacean Acid Metabolism Induction in Mesembryanthemum crystallinum L. by Cytokinin

Schmitt¹,

Piepenbrock²

1992

Plant Physiol.

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Section: Ba (Rm)supporting

confidence: 76%

“…It has been observed that cytokinin activity in xylem exudates from water-stressed sunflower plants is reduced in comparison to the exudate from well-watered controls (14). Cytokinin could therefore fulfill the role of a negative, root-derived regulator of PEPCase induction in Mesembryanthemum crystallinum.…”

mentioning

confidence: 96%

Regulation of Phosphoenolpyruvate Carboxylase and Crassulacean Acid Metabolism Induction in Mesembryanthemum crystallinum L. by Cytokinin

Schmitt¹,

Piepenbrock²

1992

Plant Physiol.

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“…The occurrence of cytokinins in the xylem sap of decapitated plants (4, 13,19,24,31) and the marked reduction in the amount of cytokinin in bleeding sap when the root system is subjected to water stress (12) or flooding (3) suggests that this hormone may be produced in the root. Pea seedlings are well suited for investigating the natural occurrence of cytokinins in roots, as Carr and Burrows (4) demonstrated that cytokinins are present in the xylem exudate of the field pea.…”

mentioning

confidence: 99%

“…For assay of cytokinin activity four pieces of soybean callus tissue, each approximately 8 mg fresh weight, were inoculated on 20 ml of medium in a 125-ml Erlenmeyer flask. The cultures were maintained at 23 C and received 12 Figure 1 represents a typical response of extracts from 0 to 1 mm pea root apices which were bioassayed at a concentration of 10 g freshweight per liter of medium. Cytokinin activities found at RF 0.1 to 0.2, RF 0.4 to 0.5, and RF 0.7 to 0.8 were designatedfactors I, II, and III respectively.…”

mentioning

confidence: 99%

“…The residue was redissolved in about 100 ml of water and adjusted to pH 2.0 with concentrated H2SO,. Fifteen milliliters of cold saturated AgNO, solution were added, and the mixture constantly was stirred for 12 hr at 4 C and centrifuged at 7000g for 15 min. The precipitate was washed with cold 2% AgNO, solution and stirred with 20 ml of 0.2 N HCl at 50 C for 30 min before being centrifuged at 7000g.…”

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confidence: 99%

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Cytokinins in Seedling Roots of Pea

1972

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The natural occurrence of cytokinins existing both in a free form and as a constituent of transfer RNA was examined in serial segments of young seedling roots of pea. Purified ethanol extracts of root apices were resolved into four factors capable of inducing soybean callus tissue proliferation. The most active factor was identified as zeatin or some closely related compound; it produced polyploid divisions and tracheary element differentiation when tested on cultured pea root segments. 2Abbreviations: IPA: 6-(3-methyl-2-butenylamino)-9-,3-D-ribofuranosylpurine or isopentenyladenosine; 2iP: 6-(3-methyl-2-butenylamino)purine or isopentenyladenine; ZR: 6-(4-hydroxy-3-methyl-2-cisbutenylamino)-9-,8-Dribofuranyosylpurine or zeatin ribonucleoside; Z: 6-(4-hydroxy-3-methyl-2-transbutenylamino)purine or zeatin. Extraction of Free Cytokinins. Immediately after harvesting, the different fractions of pea root segments were immersed separately in precooled absolute ethanol at -72 C. The frozen segments were collected by filtration on Whatman No. 1 filter paper and homogenized in an all-glass homogenizer in cold 80% (v/v) ethanol. The homogenized tissue was extracted for 3 hr in two portions of 80% ethanol and centrifuged at 10,000g for 15 min at 4 C. The original absolute ethanol fraction and the two 80% ethanol extracts were combined and the alcohol evaporated in vacuo. The water phase was adjusted to pH 8.0 and extracted with three equal volumes of 1-butanol which were then combined and taken to dryness in vacuo. The residue was redissolved in about 100 ml of water and adjusted to pH 2.0 with concentrated H2SO,. Fifteen milliliters of cold saturated AgNO, solution were added, and the mixture constantly was stirred for 12 hr at 4 C and centrifuged at 7000g for 15 min. The precipitate was washed with cold 2% AgNO, solution and stirred with 20 ml of 0.2 N HCl at 50 C for 30 min before being centrifuged at 7000g. This procedure was repeated twice. The combined acidic supernatants were adjusted to pH 2.5 with concentrated NaOH and percolated through a Dowex 50W-X8, H+ (200-400 mesh) column, 1.0 cm X 25.0 cm, which was then washed with 100 ml of water and eluted with 300 ml 3 N NH,OH. The eluate was evaporated in vacuo to about 50 ml and extracted at pH 8.0 with three equal volumes of 1-butanol which were combined and taken to dryness in vacuo. The resulting residue was dissolved in 80% ethanol and applied as a streak on Whatman No. 1 paper and developed with solvent system A, 1-butanol-acetic acid-water (12: 3:5 v/v). In addition, the following solvents were employed: B: 30 mM borate buffer at pH 8.4; C: ethyl methyl ketone saturated with water; D: l-butanol-1 N ammonium hydroxide (10:7 v/v); E: 1-butanol saturated with water. Each chromatogram was thoroughly air dried and cut into 10 equal RF strips and eluted with 80% ethanol. The eluates were reduced in volume and tested for cytokinin activity using the soybean callus bioassay.

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The Grape Root System

Richards¹

1983

Horticultural Reviews

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Kinetin‐like Activity in Root Exudate of Water‐stressed Sunflower Plants

Cited by 209 publications

References 12 publications

Regulation of Phosphoenolpyruvate Carboxylase and Crassulacean Acid Metabolism Induction in Mesembryanthemum crystallinum L. by Cytokinin

Regulation of Phosphoenolpyruvate Carboxylase and Crassulacean Acid Metabolism Induction in Mesembryanthemum crystallinum L. by Cytokinin

Cytokinins in Seedling Roots of Pea

The Grape Root System

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