Effects of glyphosate on phenolic metabolism in yellow nutsedge leaves

The action of the herbicide glyphosate [N-(phosphonomethyl)-glycine] on phenolic metabolism and phenylalanine ammonia lyase (PAL; EC 4.3.1.5) activity was investigated in yellow nutsedge (Cyperus esculentus L.). Glyphosate caused significant increases in the amount of total soluble hydroxyphenolics in the three fractions studied (neutral, acid and residual). Qualitative and quantitative differences in relation to these fractions and the amount of applied glyphosate were observed. Most of the phenolic compounds which increased after glyphosate treatment were benzoic acids (gentisic. p -OH-benzoic, salicylic and vanillic). Gentisic acid showed the greatest increase in neutral and acid fractions, being twenty- and four-fold, respectively, of the amount found in the control. PAL activity was not affected by the lowest doses of glyphosate (10−⁴and 10−³ M) , but a dramatic decrease in PAL activity was observed after 10−² M treatment. These findings, together with the low levels of cinnamic acids measured in treated yellow nutsedge plants, suggest that PAL activity is only marginally involved in glyphosate action. Since the herbicidal action probably takes place at 5-enol-pyruvylshikimate-3-P synthase (EC 2.5.1.19), an alternative pathway to PAL in phenolic biosynthesis should be activated yielding benzoic acids.     

Characterization of cyclic nucleotide phosphodiesterase activity in Phaseolus vulgaris

Cyclic nucleotide phosphodiesterase (3',5'-cyclic nucleotide nucleotidohydrolase, EC 3.1.4.17) activity isolated from Phaseolus vulgaris L. cv. Limberg seedlings was partially purified and characterized by fractional (NH₄)₂SO₄ precipitation, DEAE-cellulose chromatography, chromatography on 3',5'-cAMP-agarose, gel permeation chromatography and chromatofocusing. A crude enzyme preparation, a 30–65% (NH₄)₂SO₄ pellet, showed an acidic pH optimum. The enzyme activity was stimulated by imidazole and divalent cations such as Ca²⁺, Mg²⁺ and Mn²⁺, whereas NaF, PP_i and Fe³⁺ were inhibitory. Isobutylmethylxanthine had no significant effect on the plant enzyme. An M_I of 42 000 was estimated by gel permeation high performance liquid chromatography. By chromatography on 3',5'-cAMP-agarose a phosphodiesterase was resolved that produced 5'-AMP as sole reaction product.     

Biphasic fluence-response curves for phytochrome-mediated kalanchoë seed germination : sensitization by gibberellic Acid

The fluence-response curves for the effect of two red pulses separated by 24 hours on the germination of Kalanchoe blossfeldiana Poelln. cv Vesuv seeds, incubated on gibberellic acid (GA₃) are biphasic for suboptimal concentrations. The response in the low fluence range corresponds with a classical red/far-red reversible phytochrome mediated reaction. GA₃ induces an additional response in the very low fluence range, which is also phytochrome mediated. The sensitivity to phytochrome-far-red absorbing form (Pfr), however, is increased about 20,000-fold, so that even far-red fluences become saturating. Both in the very low and low fluence response range, the maximal responses induced by saturating fluences are modulated by the GA₃ concentration. GA₃ having no direct influence on the phytochrome phototransformations, alters the Pfr requirement and determines the responding seed population fraction in the very low and low fluence range. The effet of GA₃ appears to be on the transduction chain of the phytochrome signal.     

Cultivar and Rhizobium strain effect on nitrogen fixation and transport inPhaseolus vulgaris L.

The effects of Rhizobium strain and its interaction with plant cultivar were examined in glasshouse-grownPhaseolus vulgaris in two experiments where the physiological attributes defining the symbiotic efficiency were determined. Strains of Rhizobium significantly affected nodulation, rates of N accumulation, partitioning of N within the mature shoot and remobilizaton of the N stored in the vegetative organs to the seeds. The most efficient symbiosis (strain CO5 with Negro Argel), in comparison with the least efficient symbiosis (strain 127 K-17 with Venezuela-350) showed higher rates of C₂H₂ reduction from flowering to mid pod fill stage, evolved less hydrogen from nodules and showed higher rates of N transport as well as higher percentages of ureide-N in the xylem sap. At maturity, the best cultivar/strain association exceeded the total N accumulated in the seed and the harvest index of the poorest symbiosis in 88% and 20%, respectively. The other symbiotic combinations were intermediate in all characteristics. Nitrogen accumulation in plant shoot showed highly significant correlation with acetylene reduction rates, nodule relative efficiency, total N transport in the xylem sap and percentage of N transported as ureides.     

Elicitation of Necrosis in Vigna unguiculata Walp. by Homogeneous Aspergillus niger Endo-Polygalacturonase and by alpha-d-Galacturonate Oligomers

Endo-polygalacturonase (PG) was purified from a commercial preparation of Aspergillus niger pectinase by means of carboxymethylcellulose chromatography, preparative isoelectric focusing, and gel permeation through Sephadex G-50. The enzyme was electrophoretically homogeneous and consisted of a single polypeptide chain with a molecular weight of 33,500. The enzyme exhibited a specific activity significantly higher than those of purified polygalacturonases from phytopathogenic fungi. Galacturonate oligomers with a degree of polymerization higher than four appeared quickly as products of the enzymic hydrolysis of Napolygalacturonate. The oligomers were later degraded to di- and monogalacturonate. The homogeneous enzyme and growing mycelium of Aspergillus niger separately elicited a necrotic response in cowpea (Vigna unguiculata Walp.) pods. Heat-inactivated PG and PG inactivated with specific antibodies did not elicit necrosis, suggesting that the catalytic activity of the enzyme is necessary for its function as an elicitor. The PG-released oligosaccharides from Vigna cell wall and the galacturonides with a degree of polymerization greater than four separately elicited necrosis, whereas di- and monogalacturonate did not.     

Relative biological effectiveness (RBE) of neutrons produced by 50 MeV deuterons and by 34, 45, 65 and 75 MeV protons

RBE of p(34) + Be, p(45) + Be, p(65), + Be, p(75) + Be and d(50) + Be neutron beams produced at the cyclotron "Cyclone" of Louvain-la-Neuve were measured. The biological criterion was the regeneration of the crypts of the intestinal mucosa (50 regenerated crypts per circumference) after abdominal irradiation in mice. Taking the p(65) + Be neutrons as reference, RBE values were found equal to 1.12, 1.07, 1.00 (Ref.), 0.96 and 1.02 respectively. These results are consistent with those published for cell lethality in vitro. However, the RBE variation is smaller than this previously obtained in the laboratory for growth inhibition in Vicia faba.     

Chromosomal location of isozyme and seed storage protein genes in Dasypyrum villosum (L.) Candargy

Summary The zymogram phenotypes of glucose-phosphate isomerase (GPI), alcohol dehydrogenase-1 (ADH-1), glutamate oxaloacetate transaminase (GOT), superoxide dismutase (SOD), lipoxygenase (LPX), esterase (EST) and the banding patterns of gliadin and glutenin seed storage proteins were determined for Triticum aestivum cv. Chinese Spring (CS), Dasypyrum villosum, the octoploid amphiploid T. aestivum cv. Chinese Spring D. villosum (CS × v) (2n=8x=56; AABBDDVV), and for five CS-D. villosum disomic addition lines. The genes Gpi-V1, Adh-V1, Got-V2, and Sod-V2 coding for GPI-1, ADH-1, GOT-2, and SOD-2 isozymes were located in D. villosum on chromosome 1V, 4V, 6V, and 7V, respectively. Genes coding for gliadin- and glutenin-like subunits are located in D. villosum chromosomes 1V. There are no direct evidence for chromosomal location of genes coding for GOT-3, EST-1 and LPX-2 isozymes. The linkage between genes coding for glutenin-like proteins and GPI-1 isozymes in chromosome 1V is evidence of homoeology between chromosome 1V and the chromosomes of homoeologous group 1 in wheat.Research supported by the National Research Council (Italy) and National Science Foundation (USA). International cooperative project, Grant No. 85.01504.06 (CNR)     

Trichodorus persicus n. sp. (Nematoda: Trichodoridae) from Iran

Trichodorus persicus n. sp. is described from the Caspian region of Iran, where it was found in woodland and orchard soil. Males of the new species usually have two ventral cervical papillae anterior to the excretory pore but posterior to the base of the onchiostyle; there are three ventromedian preanal supplements, the posterior one lying near the heads of the retracted spicules; the spicules are 51–61 m long with faint transverse striations distally. Females have two pairs of lateral body pores, large rounded sclerotized thickenings at the vulva and the vagina tapers inwards in lateral view.