Influence of s-Triazines on Some Enzymes of Carbohydrates and Nitrogen Metabolism in Leaves of Pea (Pisum sativum L.) and Sweet Corn (Zea mays L.)

Abstract

Foliar applications of 2 milligrams per liter of 2-chloro-4,6-bis(ethylamino)-s-triazine, 2-methylmercapto-4-ethylamino-6-isobutylamino-s-triazine, and 2-methoxy-4-isopropylamino-6-butylamino-s-triazine caused increases in the activities of starch phosphorylase, pyruvate kinase, cytochrome oxidase, and glutamate dehydrogenase 5, 10, and 15 days after treatment in the leaves of 3-week-old seedlings of pea (Pisum sativum L.) and sweet corn (Zea mays L). The results indicate that sublethal concentrations of s-triazine compounds affect the physiological and biochemical events in plants which favor more utilization of carbohydrates for nitrate reAuction and synthesis of amino acids and proteins.It is well established that the application of a sublethal concentration of s-triazines increases the protein in plants (5,6,13,(15)(16)(17)19). In a previous study (21), we noted an increase in protein content in leaves of pea and sweet corn after foliar application of 2 to 5 mg/l solutions of s-triazine compounds. Other metabolic and compositional changes following the application of s-triazines include an increase in total soluble amino acids, and the activities of nitrate reductase, transaminase, a-amylase, starch phosphorylase, adenosine triphosphatase, and 8-aminolevulinic acid dehydratase (17,18,20), and a decrease in starch and soluble sugars (16,21). In this study, the influence of foliar applications of 2 mg/l of simazine', igran, and GS-14254 on the activities of starch phosphorylase, pyruvic kinase, glutamate dehydrogenase, and cytochrome oxidase in the leaves of pea and sweet corn is described. MATERIAL AND METHODSPea (Pisum sativum L., var. Perfected Freezer) and sweet corn (Zea mays L., var. Iochief) seeds were sown in perlite in 1.5-liter plastic pots in the greenhouse. The plants were maintained at a 16-hr photoperiod of 25 to 27 C by lengthening ambient greenhouse day length with fluorescent light and 18 to 21 C dark temperatures. When the seedlings were 3 weeks old, 2 mg/l water solutions of simazine, igran, and GS-14254 were thoroughly sprayed on the leaves. Triton B-1956 (Rohm 1 Abbreviations: simazine: 2-chloro-4, 6-bis(ethylamino)-s-triazine; igran:2-methylmercapto-4-ethylamino-6-isobutylamino-s-triazine; GS-14254: 2-methoxy-4-isopropylamino-6-butylamino-s-triazine.and Haas, Philadelphia, Pa.) was used as a surfactant. Control plants were sprayed with a water solution of the surfactant only. The leaf samples were taken for enzyme assay at 5, 10, and 15 days following spray application.Starch phosphorylase was extracted by homogenizing 2 g of leaves in 10 ml of 0.1 M tris buffer, pH 6.3. The homogenate was centrifuged at 10,000g for 10 min. The supernatant fluid was used as a source of the enzyme. The enzyme assay was conducted by using the method of Lee (9). Inorganic phosphate was determined by an adaptation of the procedure of Fiske and Subbarow (7).The extraction and assay of pyruvate kinase were conducted by using the slightly modified method described by Miller and Evans (12). For preparati...

Effects of the herbicides Lindex and Simazine on chloroplast and nodule development, nodule activity, and grain yield inLupinus albus L.

“…Tweedy and Ries, (1967) reported stimulative properties of Simazine and attributed it to its action on nitrate reductase activity. Other authors also attributed the same properties to other enzymes such as piruvate kinase (Wu et al, 1971;Wu et al, 1972). The latter enzyme regulates the formation of piruvate, and its activation results in an increase in the rate of Nz-fixation.…”

“…Certain authors (Wu et al, 1971(Wu et al, , 1972 had found that simazine had a stimulative effect on protein content and on N2-fixation by activating the nitrate-reductase and piruvate-kinase enzymes. On a cultivated soil without naturally occurring Bradyrhizobium sp.…”

Action of Simazine in Increasing Plant Protein Content

“…Singh and Salunkhe (20) reported that several enzymes were stimulated in bush bean (Phaseolus vulgaris L.) plants sprayed with IO -7 M simazine and concluded that simazine may create a metabolic condition favorable for greater use of carbohydrates for nitrate reduction and protein synthesis. Carbohydrate degrading and nitrate as similating enzymes have also been reported to be stimulated in peas (Pisum sativum L.) and sweet corn by foliar appli cations of IO -5 M simazine (26). The role of carbohydrate utilization is not clear because reports showing stimulation of carbohydrate degrading enzymes by simazine have not shown increases in total protein synthesis per plant in the same tests (20,26).…”

Role of light in the synthesis of nitrate reductase and nitrite reductase in rice seedlings

“…However, at high concentrations simazin showed the same effect as 3-(3,4-dichlorophenyl)-1,1-dimethylurea. Increase in activity of several other enzymes such as transaminase, a-amylase, starch phosphorylase, adenosine triphosphatase (Singh & Salunkhe, 1970), &-aminolaevulinate dehydratase (Wu et al, 1971a), pyruvate kinase, cytochrome oxidase and glutamate dehydrogenase (Wu et al, 1971b) as a result of application of simazin at sub-lethal concentrations has also been observed.…”