Gestur Johnson

Accumulation of phenolic substances and ascorbic acid in potato tuber tissue upon injury and their possible role in disease resistance

SummaryChlorogenic acid and other o-dihydricphenols were found to accumulate rapidly in the area adjacent to the cut surface of potato tuber slices held at room temperature in a moist chamber.The rate of accumulation was found to be decreased by: (1) holding the slices at lower temperature; (2) dipping the slices in resorcinol solution; (3) dipping slices in sodium bisulfite-sodium chloride solution; (4) immersion of whole tubers in water (room temperature) for 24 hours prior to slicing.The same phenolic substances which accumulated in tuber slices were found to accumulate in necrotic areas of tubers infected with aster yellows.Ascorbic acid was found to accumulate in tuber slices but rapidly decreased after the second day of holding at room temperature.Several ways in which phenolic substances can function in the mechanism of disease resistance are discussed.The possibility that the accumulation of oxidized products of ascorbic acid adjacent to infected tissue may play a role in disease resistance is also discussed.

Two phytoalexins from sugarbeet (Beta vulgaris) leaves

Abstract Two phytoalexins have been isolated from the leaves of sugarbeet infected with Cercospora beticola and their structures have been shown to be 2′,5-dimethoxy-6,7-methylenedioxyflavanone (1) and 2′-hydroxy-5-methoxy-6,7-methylenedioxyisoflavone (2).

The possible rôle of phytoalexins in the resistance of sugarbeet (Beta vulgaris) to Cercospora beticola

Abstract Leaves of sugarbeet ( Beta vulgaris ) infected with Cercospora beticola yield two compounds, the flavanone betagarin (C 18 H 16 O 6 ) and the isoflavone betavulgarin (C 17 H 12 O 6 ). Highly resistant cultivars appear to produce greater quantities of betavulgarin in the lesions than the more susceptible ones. Betavulgarin possesses strong antifungal activity whereas betagarin does not. It also has many of the properties of a phytoalexin and could play an important role in the resistance of sugarbeets to Cercospora beticola . The significance of betagarin is not so clearly defined. Betavulgarin possesses greater antifungal activity than the well-known active isoflavones such as biochanin A, formononetin and genistein.

PAPER CHROMATOGRAPHY-ANTHRONE DETERMINATION OF SUGARS.

Abstract Mixtures of glucose, fructose and sucrose were successfully analyzed by a method employing separation on paper, elution and colorimetric determination with the anthrone reagent. Since the anthrone reagent is employed as the colorimetric reagent, prior hydrolysis of sucrose is not necessary. The method, which requires very simple apparatus, may be used for the rapid and accurate determination of sugars in plant materials.

The glycoflavonoid pigments of wheat, Triticum aestivum, leaves

Abstract The C -glycosylflavone pigments found in wheat leaves are a varied mixture of compounds in the luteolin and apigenin series; iso-orientin, lutonarin, lucenin-1, lucenin-3, vicenin-2, and an unreported C -glycoside, wyomin, an iso-orientin derivative with rutinose at the 7-position. In addition, a 4′- O -glucosyl derivative of iso-swertisin was identified along with the previously reported flavone, tricin.

Lithospermum ruderale: Partial characterization of the principal polyphenol isolated from the roots☆

Abstract Lithospermic acid from L. ruderale roots is a polyphenolic carboxylic acid with an empirical formula believed to be C 16 H 14 O 7 . The molecule has two 1,2,4-trisubstituted benzene rings, each containing o -dihydroxy groupings; and an olefinic grouping which is conjugated with one of the rings. The last oxygen atom is probably present as a tertiary alcohol. Optical activity indicates that the molecule contains one or more asymmetric centres. The structure of this molecule is discussed.

Antifertility Activity of an Oxidized Polyphenolic Acid from Lithospermum ruderale.

Summary A polyphenolic acid, not previously described, was isolated from the roots of L. ruderale and named “lithospermic acid” (LA). LA showed no biological activity in the rat or the chicken. However, when oxidized enzymically a substance was obtained which inactivated exogenous and endogenous gonadotropins in the female rat and prevented ovulation in the laying hen. In one experiment a cold water extract of the roots was partitioned into 5 fractions which were administered orally to immature female rats. Only the original extract and one fraction (11), composed of oxidized LA showed any significant inactivation of exogenous gonadotropin. In another experiment cold water extract, II, as well as enzymically oxidized lithospermic acid showed antiovulatory properties when injected into the laying hen. These experiments indicate that oxidized LA present in the roots is responsible for some of the antigonadotropic effect noted with cold water extracts of L. ruderale.

The effects of dihydroquercetin on the cut surface of seed potatoes

The purpose of this study was to determine the effects which dihydroquercetin (DHQ) has on the natural healing process of suberization and wound periderm initiation in cut seed potatoes. Dihydroquercetin is a phenolic compound extracted from the bark of Douglas Fir,Pseudotsuga menziesii (Mirb.) Franco.Anatomical studies of treated seed potato tissue showed that treatment with bark-383, the cork-rich fraction of the whole bark containing approximately 2% pure DHQ, increases the thickness of the suberized layer formed below the cut surface. Treatment with 4% bark fraction I, which is blended to that concentration with the inert carrier dust Pyrax and contains approximately the same amount of DHQ as does the bark-383, also promoted the formation of a thicker layer of suberized cells.The thickness of the wound periderm did not significantly vary as a result of the use of any treatments containing DHQ. The use of Captan (Orthocide 50W) as a cut seed treatment in these studies was found to inhibit the formation of a suberized layer and subsequently the initiation of a wound periderm. The combination of bark-383 and Orthocide 50W in a treatment mixture reversed the inhibitory affect of the Orthocide 50W alone and therefore allowed for the formation of a well suberized layer and a wound periderm.It was found that wound healing on the cut surface of seed potatoes is largely dependent on the type of tissue present at any given point on that cut surface. Therefore, the response to treatment of the stolon end, center, and blossom end tissues was related to the type of tissue which was present in each of those tuber regions.The fungal mold growth on treated seed pieces incubated in a controlled environment was adequately retarded when Orthocide 50W was combined with bark-383 in a mixture ratio of 1:9 respectively. The longer the treatment material was allowed to remain on the seed piece, the greater was the protection against mold growth afforded by the mixture.

Comparison of two methods of PCNB application for control of Rhizoctonia infection of potatoes

A broadcast application of PCNB (Terraclor) resulted in a reasonably uniform distribution of the chemical in the soil with the concentration decreasing in a linear fashion with increasing depth in the soil profile.A banded application resuluted in a considerably higher chemical concentration at the 4–6 inch depth than at the 0–2 or the 2–4 inch depths. The problem of the lack of uniformity of chemical distribution could probably be solved by altering nozzle placement and size and allow use of the band method of application to minimize grower cost. More complete disking in the case of the broadcast treatment would probably result in a relatively uniform distribution of the chemical but at higher cost to the grower.PCNB application rates of 10, 15 and 25 lbs per acre broadcast and 71/2, 10 and 121/2 lbs per acre in a band significantly reduced the severity ofRhizoctonia infection of Russet Burbank potatoes but did not increase potato yields significantly.ResumenUna aplicación al voleo (broadcast) de PCNB (Terraclor) resultó en una rasonable distribució uniforme en el suelo, en el cual la concentración del PCNB descendía en forma lineal con el incremento de la profundidad en el perfil del suelo.Una aplicación en bandas, resultó en una considerable más alta concentración a la profundidad de 4–6 pulgadas que a 0–2 o 2–4 pulgadas. El problema de la falta de uniformidad en la distribución del producto químino pordía ser corregida regulando el rociador o por el tamaño de este, lo que permitiría el uso de este método, disminuyendo asi el costo de aplicación.Una mezcla más completa, en el caso de aplicación al voleo, podría ressultar en una relativa distribución uniforme del producto químico, pero a costo mayor para el agricultor.Aplicaciones de PCNB a dosis de 10, 15 y 25 libras por acre usando el métode de voleo y 71/2, 10 y 121/2 libras por acre en bandas, reduce significativamente la severidad de infección de Rhizoctonia en los tuberculos de la variedad Russet Burbank, pero no hubo incremento del rendimiento en forma significativa.