Francis A. Haskins

Trans-o-hydroxycinnamic acid glucosylation in cell-free extracts of Melilotus alba☆

Abstract The glucosylation of trans - o -hydroxycinnamic acid has been demonstrated in cell-free extracts of Melilotus alba . The reacton requires UDPG, a sulfhydryl compound, and an active extract from sweet clover leaves. The product of the reaction has been tentatively identified as trans -,β- D -glucosyl- o -hydroxycinnamic acid.

Sweetclover-Weevil Feeding Deterrent B: Isolation and Identification

Deterrent B, a compound apparently involved in the resistance of Melilotus infesta to the sweetclover weevil Sitona cylindricollis, has been isolated from leaves by a combination of preparative paper chromatography, sublimation, and crystallization. The compound has been identified as ammonium nitrate. Isolated deterrent B and ammonium nitrate have identical feeding deterrent activities. Although the deterrent principle was isolated as the ammonium salt, nitrate ion is probably responsible for the deterrent activity in vivo.

An Example of the Influence of Modifying Genes in Neurospora

A genetic analysis of several tryptophane- or nicotinic acid-utilizing strains of Neurospora has provided evidence that these strains have in common a mutation which prevents their growth on minimal medium, but that their responses to various growth substances are influenced by the action of a number of modifying genes. The influence of the modifiers is such that different strains which carry the same primary mutation appear to be blocked at different biosynthetic steps along the pathway which leads to the formation of tryptophane and nicotinic acid. A suppressor of the primary mutation has also been found.

Genetic Regulation of Flavonoid Content in Seeds and Seedlings of Melilotus alba

Abstract Chemical analysis of seeds and seedlings of the CC and cc genotypes in Melilotus alba indicated that these alleles affect flavonoid biosynthesis. The CC seed coats contained orientin and iso -orientin, which were absent in the cc seed coats. The pigment responsible for the red pigmentation of young seedlings of CC genotypes was a cyanidin glycoside. The embryos of seeds of both the CC and cc genotypes contained a flavonoid tentatively identified as a 6,8-di- C -pentosylapigenin. The observation that 3′,4′-dihydroxyflavonoids were absent in the cc genotype and that 4′-hydroxyflavonoids were present in both genotypes indicated that the C/c alleles controlled the 3′-hydroxylation of flavonoids. The C/c alleles did not, however, control 3′-hydroxylation of cinnamic acids since caffeic acid was detected in both genotypes.

Glucosides of Coumarinic and o-Coumaric Acids in the Tonka Bean

The β-glucosides of coumarinic and o-coumaric acids were detected in extracts of cotyledons, exocarps, and seedling leaves of the tonka bean. The existence of these compounds and the presence of a β-glucosidase having specificity for coumarinyl glucoside suggest that the tonka bean synthesizes coumarin by a pathway similar to the one found in sweetclover.

Potential for hydrocyanic acid poisoning of livestock by indiangrass.

Hydrocyanic acid or prussic acid poisoning of livestock by sorghums [Sorghum bicolor (L.)Moenchl and sudangrasses [Sorghum sudanese (Piper) StapfJ is caused by the digestive liberation of hydrocyanic acid (HCN) from the cyanogenic compound, dhurrin [(S)-p-hydroxymandelonitrile ,8-D-glucopyranosideI found in tissue of these plants. Recent research documented that dhurrin is also present in indiangrass [Sorghastrum nutans (L.) Nash] seedlings. The purpose of this study was to determine the hydrocyanic acid potential (HCN-p) of forage from established stands of indiangrass. Five cultivars representative of indiangrass germplasm of the Great Plains were sampled during the growing season for 2 years from 2 sites in eastern Nebraska. The HCN-p of the indiangrass sampled in this study exceeded 750 mg-1 kg dry wt. (dangerous level) only in spring when new growth was 20 cm tall or less. Levels were less than 500 mg-1 kg (safe) when new growth was at least 40 cm tall and were very low (<200 mg-1 kg) or not detected when the forage was over 1 m tall. Pure stands of indiangrass that are grazed when the new growth is less than 20 cm tall could be lethal to livestock.

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

Abstract 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.

Relationship between contents of leucoanthocyanidin and dhurrin in sorghum leaves

SummaryFlag leaves of ‘Colman’ forage sorghum (Sorghum bicolor) contain at least 25 times as much leucoanthocyanidin (LAC) and approximately half as much of the cyanogenic glucoside, dhurrin, as do flag leaves of ‘White Collier’ forage sorghum. Assays of flag leaves from 119 F2 plants and 11 F5 lines from crosses between these two cultivars revealed a statistically significant negative association between levels of LAC and dhurrin. Both LAC and dhurrin are aromatic compounds, and the negative association between the two may be the result of competition for intermediates or products of the aromatic biosynthetic pathway. This rationale appears to be quite different from that for the negative association reported for levels of tannin and cyanide in Lotus corniculatus. Although the negative relationship between LAC and dhurrin in sorghum was statistically significant, the association was not consistent enough to suggest that either trait could be used reliably in selecting or breeding to modify the other trait.

Dhurrin and p -Hydroxybenzaldehyde in Seedlings of Various Sorghum Species

Abstract 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.

Influence of Spectral Composition of Light on cis-trans Interconversion of o - Hydroxycinnamic Acid

Abstract Spectrophotometric and fluorometric determinations were made of the influence of light transmitted by various filters upon cis-trans interconversion in basic solutions of o-hydroxycinnamic acid. Wavelengths longer than 450 mμ were found to be without effect in interconverting the two isomers. Exposure of basic solutions to light of effective wavelengths resulted in the establishment of equilibria between the cis and trans isomers. Within the range of effective wavelengths, decreases in wavelength were associated with increases in percentage of trans isomer in the equilibrium mixture.