Soluble Amino Acid Content Research Articles

Effects of the herbicide methabenzthiazuron on the physiology of wheat plants

AbstractSpring wheat (Triticum aestivum L. “Caribo”) was grown in vermiculite containing methabenzthiazuron (N‐(benzothiazol‐2yl)‐NN′‐dimethylurea) presowing. Effects of the herbicide on plant development and plant composition were analysed up to an age of 4 weeks.Inhibition of photosynthetic oxygen evolution represented the primary effect induced by the herbicidal treatment and led to a decreased concentration of soluble reducing sugars. Photosynthetic activity however recovered after 3 weeks and even increased above control values. Secondary effects following methabenzthiazuron treatment included a delayed chlorophyll breakdown, a decreased chlorophyll a/b ratio, enlarged chloroplasts, an increased concentration of soluble amino acids and of soluble protein, and an increased in vitro nitrate reductase activity. These responses are taken to indicate an increased photosynthetic and metabolic capacity in methabenzthiazuron treated wheat plants.Comparable results can be obtained with plants grown at low light intensities. It is concluded that the “physiological effects” observed in wheat plants after treatment with methabenzthiazuron are similar to a natural adaptation reaction to low light intensities. It is assumed that this adaptation reaction is caused by a low concentration of soluble reducing sugars.Experiments with plants growing at different light intensities indicated that effects due to herbicidal action were more pronounced at high light intensities.Measurements on daily fluctuations revealed a peak around noon for the sugar content and the nitrate reductase activities measured in vivo as well as in vitro. In vivo nitrate reductase activity in plants treated with 5 parts/million methabenzthiazuron was very low, presumably because of lack of sugars for the production of NADH. The protein concentration was increasing and the amino acids were decreasing during the day in herbicide treated plants, possibly indicating increased protein synthesis in the light in plants treated with methabenzthiazuron.

Utilization of arginine dy rice callus tissue

Abstract Arginine is widespread in the plant kingdom, sometimes accumulated in high concentrations. Information on the accumulation of arginine has been obtained with ammonium-excess rice plants (9), potassium-deficient rice plants (8), phosphorus-deficient mulberry leaves (4), and loblolly pines grown with urea (14). The amount of arginine in plants varies widely. In young apple trees arginine is the most important compound to store nitrogen. However it is reduced when new growth occurrs (13). Vernalized wheat loses its arginine content, a major constituent of the soluble amino acid content of untreated wheat (18). On germination, beans decreases the amount of arginine (1). In tulips the nitrogen economy revolves around arginine (20).

Changes in polysomes in Nicotiana glutinosa L. leaves infected with lettuce necrotic yellows virus

Polysomes have been studied in extracts of leaves of Nicotiana glutinosa L. infected systemically with lettuce necrotic yellows virus (LNYV). Before symptoms appeared, at the time of rapid virus synthesis, no changes in polysome concentration or size distribution were observed compared with healthy leaves. However, in infected leaves treated with actinomycin D (AMD) and labelled with 32P, increased ribonuclease-sensitive radioactivity was observed in the fractions of sucrose gradients containing polysomes, and three labelled nucleic acids were isolated from the fractions containing monosomes and polysomes. Uninfected, control leaves showed very much lower ribonuclease-sensitive radioactivity in the fractions containing polysomes, and the monosome-polysome fractions contained only one of the three radioactive nucleic acids detected in infected leaves. It is suggested that the radioactive nucleic acids found in infected leaves treated with AMD could be associated with LNYV-specific polysomes. Commencing with the appearance of symptoms, extracts of infected leaves showed a decrease in the proportion of ribosomes occurring as polysomes, compared with healthy leaves. As symptoms developed, the proportion of ribosomes occurring as polysomes continued to decline more rapidly than in healthy leaves and this was accompanied by a net loss of ribosomes. Within a day of the appearance of symptoms the ability of infected leaves to incorporate [ 14C]valine into protein had declined compared with healthy leaves. This suggested that symptom production in LNYV-infected N. glutinosa was accompanied by a reduced rate of protein synthesis. An observed general increase in the content of soluble amino acids, amines and peptides in infected leaves indicated that the reduced rate of protein synthesis was not due to a decrease in the size of the amino acid pool.

Der Einfluß der Kalium‐Ernährung auf den Gehalt und das Spektrum löslicher Aminoverbindungen in Rotklee (Trifolium pratense L.)

Effect of potassium nutrition on the content and the spectrum of soluble amino compounds in Red Clover1. A better K nutrition of Red Clover (Trifolium pratense) resulted in higher contents of soluble amino acids of the upper plant parts. The plants of the treatment with the highest K application showed nearly double as high contents of glutamic acid, aspartic acid, alanine and γ‐aminobutyric acid than the plants of the K0 treatment. The content of asparagine was not as much affected by the K nutrition and the content of glutamine was even lowered.2. Red Clover responded on the K treatment with its content of soluble amino compounds quite different than non leguminous plant species which show decreasing contents of soluble amino acids with an increasing K nutrition. Therefore it is concluded, that the K nutrition of legumes affects the N2‐fixation of Rhizobium leguminosarum.3. The higher contents of soluble amino compounds did not influence the protein content of the upper plant parts. But with the better K supply the yields were increased considerably and therefore also higher yields of proteins were harvested. Very low K supply resulted in a high protein content, due to an inhibition of plant growth.

Untersuchungen über den Einfluß des Kinetins und des Eisens auf den Nukleinsäure‐ und Proteinstoffwechsel von Karottengewebekulturen

The Influence of Kinetin and Iron on Nucleic Acid and Protein Metabolism of Carrot Tissue CulturesCarrot‐root tissues cultured in a nutrient solution containing Kinetin had a high rate of cell division, that led to an undifferentiated callus, and a relatively low DNA content per cell. The same tissues growing without Kinetin had a smaller rate of cell division and a higher DNA content, and showed the ability to form roots.By addition of 32P to the nutrient solution, the cultures growing with Kinetin showed a higher specific activity of DNA than those growing without Kinetin.From previous experiments and results of other workers the possibility of the occurence of a metabolic labile DNA fraction in the cultures which grew without Kinetin is discussed.A comparison between the influence of iron and Kinetin on cell division activity, root formation, DNA, RNA and amino acid content of the tissue cultures was made on a cell basis. Iron deficiency or absence of Kinetin in the nutrient solution reduced the cell division activity of carrot tissue cultures and increased the content of DNA, RNA and soluble amino acids. The protein content was reduced by iron deficiency but was increased by the absence of Kinetin.Cultures, growing without Kinetin were able to form roots, while those, growing in an iron deficient medium were unable to show the latter phenomenon.