Dhurrin and p-hydroxybenzaldehyde in seedlings of various Sorghum species

Week-old shoots of 50 Sorghum entries representing 22 species, plus four Sorghum entries of undesignated species, were dried at 75° and the dried tissue extracted with water at room temperature. The resulting extracts were diluted in 0.1 M sodium hydroxide and spectra were scanned immediately to provide a measure of free p-hydroxybenzaldehyde. Scans were repeated after the basic solutions had stood for 3 hr at room temperature to permit hydrolysis of dhurrin (S-p-hydroxymandelonitrile β-D-glucopyranoside). Without exception, the quantity of free p-hydroxybenzaldehyde was very small in relation to the quantity released by dhurrin hydrolysis.     

Soluble sugars of maize seedlings

The soluble sugars were determined in different parts of maize seedlings (seeds, roots and shoots), 0, 2, 4 and 6 days after sowing.     

Free amino acids of maize seedlings

The free amino acids were determined in different parts of maize seedlings (seeds, roots and shoots), 0, 2, 4 and 6 days after sowing.     

Polyamines in barley seedlings

Polyamine levels in barley seedlings grown in the dark or in diurnal illumination have been determined, by direct dansylation, 3, 6 and 12 days after g     

Biochemical changes during seed development in sorghum (Sorghum bicolor)

Grain dry weight accumulation, soluble sugars, starch, protein, fat and ash contents were studied in developing grains of eight sorghum cultivars. The     

The biosynthesis of coumarylagmatine in barley seedlings

An enzyme present in extracts of the shoots of barley seedlings has been shown to synthesize coumarylagmatine from p-coumaryl-coenzyme A and [U-¹⁴C]agmatine.     

Peroxidase-mediated hydroxylation of p-hydroxyphenylacetonitrile,an intermediate in dhurrin synthesis in sorghum

A soluble enzyme from sorghum seedlings mediates the aliphatic hydroxylation of p-hydroxyphenylacetonitrile. The reaction was dependent on the pres     

Agmatine coumaroyltransferase from barley seedlings

4-Coumaroyl-CoA: agmatine N-4-coumaroyltransferase (agmatine coumaroyltransferase; ACT) from barley seedlings was purified with a 100-fold increase     

Arginine Decarboxylase of oat seedlings

Arginine decarboxylase activity in the shoots of seedlings was high in oats, intermediate in barley and low in rice, maize, wheat and rye. After partial purification, the arginine decarboxylase from the shoots of potassium deficient oat seedlings was separated into two fractions, A (MW 195 000) and B (MW 118 000), by gel chromatography. On gel electrophoresis, the mobilities of these fractions were respectively 0.12 and 0.55 relative to bromophenol blue at pH 9.5. Fraction A was twice as active as fraction B in extracts of seedlings grown with both normal and potassium deficient nutrition, despite the greater activity ( × 5) of the potassium deficient plants. The properties of the two fractions were similar with respect to pH optimum (7–7.5), K_m (3 × 10 ^?5M) and the effect of inhibitors. Fraction A was purified to apparent homogeneity by DEAE-cellulose chromatography. The enzyme was specific for l-arginine and it was strongly inhibited by NSD 1055, d-arginine and canavanine. Mercaptoethanol and dithiothreitol stimulated the enzyme by ca 50% and p-chloromercuribenzoate was an inhibitor. Pyridoxal phosphate stimulated activity by ca 30% and EDTA stimulated activity by 30%. Ca²⁺ and Mg²⁺ inhibited the enzyme by 50% at ca 20 mM. Putrescine and the polyamines showed only moderate inhibition at 10 mM, but agmatine reduced activity to 30% at this concentration.     

A cyclic AMP binding-protein from barley seedlings

A protein fraction extracted from barley seedlings was shown to bind 3′:5′-cyclic AMP. The binding effect is real and not due to interference with the standard binding-protein assay used. Evidence is presented that this is a specific binding-protein; even at high concentrations other protein fractions from the same source showed no affinity for cyclic AMP. None of a range of cyclic and non-cyclic nucleotides that were examined exhibited a degree of binding with the protein comparable to that with cyclic AMP. The cyclic AMP/binding protein complex has a K_d of 8 nM. This complex eluted at an identical position in the elution sequence from a Sephadex G-150 column as the uncomplexed binding-protein. The barley binding-protein is in a fraction which also exhibits the enzymic activities of glucose 6-phosphatase, ATPase, 5′-nucleotidase, and fructose 1,6-diphosphatase.     

Is p-hydroxybenzaldehyde a major constituent of epicuticular wax from Sorghum bicolor seedlings?

Free p-hydroxybenzaldehyde was not present in appreciable quantity on the surface or in the interior of week-old Sorghum bicolor shoots that had been heated to inactivate hydrolytic enzymes, nor was p-hydroxybenzaldehyde detected in epicuticular wax of greenhouse-grown sorghum ca 4.5 months old.     

Oxygen incorporation in the biosynthesis of p-coumaric acid in seedlings of Zea mays

The results of experiments in which seedlings of Zea mays were grown in the light in an atmosphere enriched with oxygen-18 indicated that the hydroxyl oxygen atom in p-coumaric acid is derived from molecular oxygen.     

Starch and water-soluble polysaccharides from sugary endosperm of sorghum

The starch water-soluble polysaccharides from sugary (su) endosperm of sorghum were isolated and characterized. Starch granule structure and co     

p-Hydroxybenzaldehyde as a major constituent of the epicuticular wax of seedling Sorghum bicolor

p-Hydroxybenzaldehyde is present in concentrations up to 30% in the wax of Sorghum bicolor seedlings. It is highly deterrent to locusts, reducing their normal feeding by 90%.     

Role of an indole alkaloid in the resistance of barley seedlings to aphids

The content of the simple indole alkaloid gramine in barley leaves decreased with age. Conversely, susceptibility to aphids increased in older plants. Population growth rate of the greenbug Schizaphis graminum correlated with gramine content of leaves of several barley cultivars. Gramine decreased rate of feeding, survival and reproductive index of aphids feeding on artificial diets at concentrations similar to those found in plant leaves. Thus, it is suggested that gramine plays a role in the resistance of barley seedlings to S. graminum. Benzyl alcohol, a previously reported insect resistance factor from barley, was absent from all barley cultivars analysed.     

Turnover of coniferin in pine seedlings

Coniferin (coniferyl alcohol-β-d-glucoside) was not detected in pine seeds (Picea abies) but it accumulated in the stems and roots of pine seedlings. Pulse labeling experiments with l-phenylalanine-[U-¹⁴C] and 100-day-old pine seedlings in hydroponic solution showed a turnover of coniferin with a half life of about 60 hr. Pulse labeling with ¹⁴CO₂ and seedlings kept in soil gave a half life of about 120 hr for coniferin. The results indicate that coniferin could be an intermediate of lignin biosynthesis in pine seedlings.     

The conversion of 3-deoxyarabinoheptulosonate 7-phosphate to 3-dehydroquinate by sorghum seedling preparations

Partially purified preparations from etiolated sorghum seedlings catalyzed the conversion of DAHP to DHQ. The reaction catalysed by DHQ synthetase was stimulated by 0.1 μM to 0.1 mM NAD in the presence O-0.5 mM Co²⁺. NADH at 1 μM stimulated the reaction as much as 50% but became inhibitory at 100μM. Co²⁺ at 0.5mM stimulated enzyme activity 3-fold; Mg²⁺, Mn²⁺, Cu²⁺, and Zn²⁺ were not stimulatory. EDTA at 5 mM inhibited the reaction 95% but its effects were reversed by equal concentrations of Co²⁺. Phe, Tyr, Trp, t-cinnamate, several hydroxylated cinnamates, DHS, quinate, and shikimate at 0.3 mM failed to affect enzyme activity but slight inhibition occurred with DHQ and protocatechuic acid at 0.3 mM, inhibition being 14 % and 22 %, respectively. DHQ synthetase activity also was detected in spinach leaves and potato tuber tissue. Synthetase activity appeared to increase in response to injury of potato tuber and sweet potato root tissues.     

Oxidation of p-coumaroylagmatine in barley seedling extracts in the presence of hydrogen peroxide or thiols

When p-coumaroylagmatine is oxidized in the presence of hydrogen peroxide in a crude extract of barley seedlings, among several products, hordatine A is formed. However, unlike the natural isomer, this is optically inactive. In the absence of hydrogen peroxide and when a thiol (glutathione, cysteine, mercaptoethanol or dithiothreitol) is added to the incubation medium, p-coumaroylagmatine is rapidly transformed to a thiol adduct, probably through a peroxidase-dependent co-oxidation reaction. The reactions with hydrogen peroxide or with a thiol are completely inhibited by 1 mM ascorbate.     

Dhurrin,the cyanogenic glucoside of Cercocarpus ledifolius

Dhurrin (2-β-d-glucopyranosyloxy-2-(4-hydroxy)phenyl-2S-acetonitrile) was isolated as a cyanogenic compound from Cercocarpus ledifolius and identified by its hydrolysis products, chromatographic properties and ¹H NMR spectroscopy.