Cress, seedlings

Sandmann, G., 1993. Detection of bleaching by benzoyl cyclohexanediones in cress seedlings by HPLC separation and determination of carotenoids. In Target Assays for Modern Herbicides and Related Phytotoxic Compounds. P. Boger G. Sandmann (Eds), Lewis Publishers, Boca... 

Compound Lettuce/Cress Seedling Assays Promotion 8Root Growth at 10-6M Inhibition... 

The procedure of Chen ef al. (C7) separated the ascorbic acid on paper using n-butanol or phenol saturated with oxalic acid to retard decomposition. A preliminary preparative separation could be used to concentrate the sample. Qualitative identification was made from the R/ of the spots located by spraying with 0.08 % 2,6-dichlorophenolindophe-nol, and quantitative analysis by elution with oxalic acid and titration with the same dye. Recoveries from urine and cress seedlings were 85 % or more at even the lowest concentrations tested (0.5 mg/ml), and the method could detect 1-2 fig ascorbic acid per cm of paper. The method clearly separated L-ascorbic acid and D-araboascorbic acid as well as hydroxytetronic acid, reductinic acid, and reductone. 

Phytotropins are synthetic molecules which affect the tropic responses, inhibit auxin transport and bind to the receptor for 1-N-naphthylphthalamic acid (NPA) (10-1) [91-93]. For a recent review see [94]. A simple assay to detect and compare activities is measurement of antigravitropic activity on cress seedlings [95]. There are two phytotropin recognition sites on the NPA receptor, or two receptors, which recognize phytotropins... 

Etiolated cress seedlings incubated with ALA or chelators confirm the increase of pchl(ide) (Fig.2) in the dark (2, 12). In accordance to earlier data (1), the chlorophyll content of ALA-fed plants is slightly higher in the lag phase of chlorophyll synthesis (2h light), whereas after 12h illumination (Fig.l) the chlorophyll content is diminished (14). 

In summary, treatment of cress seedlings with chelators leads to increased accumulation of chlorophyll precursors in the dark, but decreased accumulation of chlorophylls in the light. Two possible points of attack are indicated by the present results decreased activity of chlorophyll synthetase and diminished accumulation of chlorophyll proteins, e.g. LHCP. 

Sugar Acid Derivatives Fed to Cress Seedlings or Injected into Bats CSompounds ia capitid letters give rise to ir scorbic acid in plant or animal, but compounds in italics give D-araboascorbic acid in the plant or animal as shown. 

It is of interest to note, however, that the configuration of the hydroxyl on C-3 affects the ease with which the substance is transformed into ascorbic acid in the plant the enzyme concerned reacts more readily with the lactone which has the n-configuration i.e., with the L-galactono ring structure), but in animals the difference is not so obvious. When an unnatural lactone is provided, this differing specificity of the plant and animal enzymes is more clearly shown. With plants (cress seedlings, mung beans, and peas) n-altrono-y-lactone only is converted to n-arabo-ascorbic acid, whereas with rats only D-mannono-y-lactone yields this ascorbic acid. 

The form in which nitrogen is supplied to the plant is certainly important, but the effects observed have not always been consistent. Some reports indicate that plants supplied with nitrate contain less ascorbic acid than those grown on ammonium salts (Jones et al., 1944 Finch et cd., 1945 Wittwer, 1945). In other studies the reverse has been reported. With cress seedlings the effect of ammonium nitrogen depends on the type of ammonium salt fed. Ammonium sulfate and chloride depress the synthesis of ascorbic acid, but ammonium bicarbonate, acetate, or succinate have relatively little effect (Mapson et cd., 1947). When the cation of the salt is NH4+ and combined with a nonutilizable anion, e.g., sulfate or chloride, there is a marked depressant effect on the synthesis, which is reduced when the cation is combined with a utilizable anion, e.g., nitrate, succinate, bicarbonate, or acetate. Conversely, Na or K salts, when combined with a utilizable anion, increase the synthesis to a greater extent than when they are supplied in combination with nonutilizable anions. 

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