The Experts below are selected from a list of 2367 Experts worldwide ranked by ideXlab platform
Binne Zwanenburg - One of the best experts on this subject based on the ideXlab platform.
-
synthesis of a phthaloylglycine derived strigol analogue and its germination stimulatory activity toward seeds of the parasitic weeds Striga Hermonthica and orobanche crenata
Journal of Agricultural and Food Chemistry, 1997Co-Authors: Gerard H L Nefkens, Jan Willem Thuring, Marco F M Beenakkers, Binne ZwanenburgAbstract:The newly designed strigol analogue Nijmegen 1 (rac 7) was prepared in high overall yield starting from N-phthaloylglycine. This relatively simple analogue exhibits high bioactivity in the stimulation of germination of seeds of the parasitic weeds Striga Hermonthica and Orobanche crenata. Nijmegen 1 was resolved in its enantiomers 7 and ent 7 by using the homochiral latent D-rings ent 11 and ent 12. The enantiomers 7 and ent 7 show significant differences in germination activity. Keywords: Striga; Orobanche; germination; strigol analogue
-
asymmetric synthesis of all stereoisomers of the strigol analogue gr24 dependence of absolute configuration on stimulatory activity of Striga Hermonthica and orobanche crenata seed germination
Journal of Agricultural and Food Chemistry, 1997Co-Authors: Jan Willem Thuring, Gerard H L Nefkens, Binne ZwanenburgAbstract:All four optically pure stereoisomers of the strigol analogue GR24 were prepared via two different routes. In the first approach enantiopure ABC-fragments 4 were used as the chiral source, whereas in the alternative route both antipodes of the latent D-ring 6 were employed. Bioassays revealed significant differences in activity between the four stereoisomers in the stimulation of germination of the parasitic weeds Striga Hermonthica and Orobanche crenata. Keywords: Striga; Orobanche; germination, GR24
-
N-phthaloylglycine-derived strigol analogues. Influence of the D-ring on seed germination activity of the parasitic weeds Striga Hermonthica and Orobanche crenata
Journal of Agricultural and Food Chemistry, 1997Co-Authors: Jan Willem Thuring, Gerard H L Nefkens, H.h. Bitter, M.m. De Kok, A.m.d.a. Van Riel, Binne ZwanenburgAbstract:Several strigol analogues with modifications in the D-ring were synthesized and assayed for germination stimulatory activity of seeds of Striga Hermonthica and Orobanche crenata. All of these D-ring analogues are derived from N-phthaloylglycine as the common ABC-fragment. It was concluded that the correct structure of the 2(5H)-furanone D-ring is essential to retain full biological activity. Keywords: Striga; Orobanche; germination; strigol analogue
Jan Willem Thuring - One of the best experts on this subject based on the ideXlab platform.
-
synthesis of a phthaloylglycine derived strigol analogue and its germination stimulatory activity toward seeds of the parasitic weeds Striga Hermonthica and orobanche crenata
Journal of Agricultural and Food Chemistry, 1997Co-Authors: Gerard H L Nefkens, Jan Willem Thuring, Marco F M Beenakkers, Binne ZwanenburgAbstract:The newly designed strigol analogue Nijmegen 1 (rac 7) was prepared in high overall yield starting from N-phthaloylglycine. This relatively simple analogue exhibits high bioactivity in the stimulation of germination of seeds of the parasitic weeds Striga Hermonthica and Orobanche crenata. Nijmegen 1 was resolved in its enantiomers 7 and ent 7 by using the homochiral latent D-rings ent 11 and ent 12. The enantiomers 7 and ent 7 show significant differences in germination activity. Keywords: Striga; Orobanche; germination; strigol analogue
-
asymmetric synthesis of all stereoisomers of the strigol analogue gr24 dependence of absolute configuration on stimulatory activity of Striga Hermonthica and orobanche crenata seed germination
Journal of Agricultural and Food Chemistry, 1997Co-Authors: Jan Willem Thuring, Gerard H L Nefkens, Binne ZwanenburgAbstract:All four optically pure stereoisomers of the strigol analogue GR24 were prepared via two different routes. In the first approach enantiopure ABC-fragments 4 were used as the chiral source, whereas in the alternative route both antipodes of the latent D-ring 6 were employed. Bioassays revealed significant differences in activity between the four stereoisomers in the stimulation of germination of the parasitic weeds Striga Hermonthica and Orobanche crenata. Keywords: Striga; Orobanche; germination, GR24
-
N-phthaloylglycine-derived strigol analogues. Influence of the D-ring on seed germination activity of the parasitic weeds Striga Hermonthica and Orobanche crenata
Journal of Agricultural and Food Chemistry, 1997Co-Authors: Jan Willem Thuring, Gerard H L Nefkens, H.h. Bitter, M.m. De Kok, A.m.d.a. Van Riel, Binne ZwanenburgAbstract:Several strigol analogues with modifications in the D-ring were synthesized and assayed for germination stimulatory activity of seeds of Striga Hermonthica and Orobanche crenata. All of these D-ring analogues are derived from N-phthaloylglycine as the common ABC-fragment. It was concluded that the correct structure of the 2(5H)-furanone D-ring is essential to retain full biological activity. Keywords: Striga; Orobanche; germination; strigol analogue
Kipngeno J. Rugutt - One of the best experts on this subject based on the ideXlab platform.
-
In vitro germination of Striga Hermonthica and Striga aspera seeds by 1-aminocyclopropane-1-carboxylic acid
Natural Product Research, 2003Co-Authors: Kipngeno J. Rugutt, Joseph K. Rugutt, Dana K. BernerAbstract:Treatment of conditioned seeds of four isolates of Striga Hermonthica and one isolate of Striga aspera with various concentrations of the ethylene precursor, 1-aminocyclopropane-1-carboxylic acid (ACC), caused complex stimulation of germination patterns. GR 24, the strigol analogue served as a positive control and its stimulatory activity was comparable to that of ACC. When conditioned Striga seeds were treated with negative control that did not contain ACC, the stimulatory effect was lost. Overall, the germination data suggested a hormonal mode of action by ACC, which involves indirect stimulation of biosynthesis of ethylene that then triggers seed germination. The various mechanisms that have been proposed for the chemical and biological oxidation of ACC to generate ethylene are discussed.
-
Stimulation of Striga Hermonthica Seed Germination by 11β,13-Dihydroparthenolide
Journal of Agricultural and Food Chemistry, 1997Co-Authors: Joseph K. Rugutt, Kipngeno J. RuguttAbstract:Germination tests of Striga Hermonthica seeds were performed using 11β,13-dihydroparthenolide (DHP), a sesquiterpene lactone from Ambrosia artemisifolia (common ragweed). In each test series aqueous solutions with acetone or methanol were used as negative controls. Test solutions of the strigol analogue 2-methyl-4-((2-oxo-2,3,3a,8b-tetrahydro-4H-indeno[1,2-b]furan-3-ylidene)methoxy)-but-2-en-4-olide (GR 24) in methanol as carrier system were used as positive controls. A decrease in concentration of DHP from 10 -3 to 10 -20 M resulted in several unusual minima and maxima of stimulatory activities, suggesting that the mode of action of DHP could be hormonal. The crystal structure of DHP was determined by X-ray crystallography, and the use of molecular modeling in predicting the biologically active conformations is proposed.
Gerard H L Nefkens - One of the best experts on this subject based on the ideXlab platform.
-
synthesis of a phthaloylglycine derived strigol analogue and its germination stimulatory activity toward seeds of the parasitic weeds Striga Hermonthica and orobanche crenata
Journal of Agricultural and Food Chemistry, 1997Co-Authors: Gerard H L Nefkens, Jan Willem Thuring, Marco F M Beenakkers, Binne ZwanenburgAbstract:The newly designed strigol analogue Nijmegen 1 (rac 7) was prepared in high overall yield starting from N-phthaloylglycine. This relatively simple analogue exhibits high bioactivity in the stimulation of germination of seeds of the parasitic weeds Striga Hermonthica and Orobanche crenata. Nijmegen 1 was resolved in its enantiomers 7 and ent 7 by using the homochiral latent D-rings ent 11 and ent 12. The enantiomers 7 and ent 7 show significant differences in germination activity. Keywords: Striga; Orobanche; germination; strigol analogue
-
asymmetric synthesis of all stereoisomers of the strigol analogue gr24 dependence of absolute configuration on stimulatory activity of Striga Hermonthica and orobanche crenata seed germination
Journal of Agricultural and Food Chemistry, 1997Co-Authors: Jan Willem Thuring, Gerard H L Nefkens, Binne ZwanenburgAbstract:All four optically pure stereoisomers of the strigol analogue GR24 were prepared via two different routes. In the first approach enantiopure ABC-fragments 4 were used as the chiral source, whereas in the alternative route both antipodes of the latent D-ring 6 were employed. Bioassays revealed significant differences in activity between the four stereoisomers in the stimulation of germination of the parasitic weeds Striga Hermonthica and Orobanche crenata. Keywords: Striga; Orobanche; germination, GR24
-
N-phthaloylglycine-derived strigol analogues. Influence of the D-ring on seed germination activity of the parasitic weeds Striga Hermonthica and Orobanche crenata
Journal of Agricultural and Food Chemistry, 1997Co-Authors: Jan Willem Thuring, Gerard H L Nefkens, H.h. Bitter, M.m. De Kok, A.m.d.a. Van Riel, Binne ZwanenburgAbstract:Several strigol analogues with modifications in the D-ring were synthesized and assayed for germination stimulatory activity of seeds of Striga Hermonthica and Orobanche crenata. All of these D-ring analogues are derived from N-phthaloylglycine as the common ABC-fragment. It was concluded that the correct structure of the 2(5H)-furanone D-ring is essential to retain full biological activity. Keywords: Striga; Orobanche; germination; strigol analogue
S. K. Kim - One of the best experts on this subject based on the ideXlab platform.
-
Yield losses in maize due to Striga Hermonthica in West and Central Africa
International Journal of Pest Management, 2002Co-Authors: S. K. Kim, V. O. Adetimirin, R. DossouAbstract:Striga Hermonthica (Del.) Benth. is the most important species of parasitic weed affecting cereal crop production in Africa. Yield losses due to the parasite and yield advantages offered by tolerant maize varieties were estimated from experiments conducted in West and Central Africa between 1983 and 1989. The experiments were carried out under natural infestation in experiment stations and farmers' fields, and under uniform artificial infestation in the screenhouse. TZB and PR7843, the two most widely grown open-pollinated (OP) varieties in West and Central Africa, were susceptible to Striga with yield losses of 68 and 79%, respectively. Yield losses of 100 randomly drawn (hybrid and OP) varieties averaged 68%. Yield loss was determined by the level of tolerance of the host variety and by the severity of infestation. Tolerant varieties suffered lower yield reductions and, often, produced 2.0 - 2.5 times the yield of susceptible varieties, especially under high infestation. Grain yield was significantly co...
-
Effects of Striga Hermonthica on yield components in maize.
The Journal of Agricultural Science, 2000Co-Authors: V. O. Adetimirin, M. E. Aken'ova, S. K. KimAbstract:A split-plot experiment was conducted in 1992 and 1993 at Mokwa in the southern Guinea savanna zone of Nigeria to determine the responses of maize yield components to infestation by parasitic weed Striga Hermonthica (Del.) Benth. and identify the most important yield components under Striga parasitism. Infestation treatments (infested v . non-infested) and hybrids [9022-13 (highly tolerant), 8644-31 (moderately tolerant), 8321-21 (moderately susceptible) and 8338-1 (highly susceptible)] were the main and subplots, respectively. Striga significantly reduced grain yield and all the yield components considered. Pre-flowering stress due to Striga parasitism was higher than post-flowering stress and resulted in higher reduction for ears per plant (44%) than reductions for other yield components (12–29%). The numbers of yield components for which the hybrids exhibited the highest percentage reduction increased with the degree of susceptibility to Striga . Thus, 8338-1, the highly susceptible hybrid, suffered more severe reductions in a larger number of yield components than the other hybrids. Number of ears per plant was a major yield component and accounted for an overwhelming proportion ( R 2 = 0·95) of the variation in grain yield under Striga . Reductions in maize grain yield and its components were more severe under the moisture stress that occurred in 1992.
-
Genetics of Maize Tolerance of Striga Hermonthica
Crop Science, 1994Co-Authors: S. K. KimAbstract:A parasitic weed, Striga Hermonthica (Del.) Benth., infects millions of hectares of arable land in sub-Saharan Africa, and it threatens production of cereal crops. The objectives of this study were to investigate inheritance in maize (Zea mays L.) inbred lines of tolerance and resistance to S. Hermonthica, based on visible host plant symptoms and Striga emergence counts. A diallel cross involving 10 inbreds was tested under Striga infested fields at Mokwa, Nigeria, for 5 yr. Host plant response was rated on a scale of 1 (no symptoms) to 9 (plants dead or dying) [...]