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PubMed2001

[Construction of genetic map in sorghum and fine mapping of the germination stimulant production gene response to Striga asiatica].

Sorghum is the fifth important crop in the world. It is also the major food resource in African countries. Striga asiatica is a parasitism weed on sorghum and some other important crops. In this report, two sorghum lines with the difference in response to Striga asiatica, SRN39 (lower Germination Stimulant-GermStim production) and Shanguihong (high GermStim production), were selected as the parents for the construction of a recombinant inbred (RI) population. Ninety-four RI lines were collected for the molecular analysis and GermStim production evaluation. A genetic map was constructed with 251 molecular markers that distributed on 10 different linkage groups. The map covers sorghum genome of 1,779 cm with an average map distance of 7.1 cm between linked markers. It is one of the complete sorghum molecular map in the world. Co-segregation analysis indicated that the germination stimulant gene (GermStim) was located on linkage group J, which was at a distance of 13 cm from the closed marker. Further RAPD analysis between two parents and two DNA pools different in the amount of germination stimulant production, several polymorphic DNA fragments were identified and cloned. Mapping results showed two of them flanked with the GermStim gene at a distance of 1.6 cm and 2.1 cm respectively.

Chromosome Mapping↗
PubMed2003

Antioxidant activity of the ethanolic extract of Striga orobanchioides.

Plants containing flavonoids have been reported to possess strong antioxidant properties. The ethanolic extract of Striga orobanchioides was screened for in vitro and in vivo antioxidant properties using standard procedures. The ethanol extract exhibited IC(50) values of 18.65+/-1.46 and 11.20+/-0.52 micro g/ml, respectively in DPPH and nitric oxide radical inhibition assays. These values were less than those obtained for ascorbic acid and rutin, used as standards. In the in vivo experiments the extract treatment at 100mg/kg body weight dose caused a significant increase in the level of the catalase in the liver and the kidneys. A significant increase in the level of SOD in the liver was observed. The treatment also caused a significant decrease in the TBA-RS and increase in the ascorbic acid levels. These results suggest strong antioxidant potentials of the ethanolic extract of S. orobanchioides.

Animals↗
PubMed2003

Analysis of strigolactones, germination stimulants for striga and orobanche, by high-performance liquid chromatography/tandem mass spectrometry.

A simple and rapid analytical method for strigolactones, germination stimulants for the root parasitic weeds witchweed (Striga spp.) and broomrape (Orobanche spp.), has been developed using high-performance liquid chromatography connected to tandem mass spectrometry (LC/MS/MS). The natural strigolactones (strigol, sorgolactone, orobanchol, and alectrol) were clearly separated and identified by LC/MS/MS. As low as 0.1 pg/microL of strigol and 0.5 pg/microL of sorgolactone could be quantified, whereas 1 pg/microL was needed for the quantification of orobanchol (S/N > 10). Using this method, it was found that red clover produces orobanchol and alectrol but not strigol. The roots of red clover seedlings were found to produce 13, 70, 58, and 65 pg of orobanchol/plant 1, 2, 3, and 4 weeks after germination, respectively.

Chromatography, High Pressure Liquid↗
PubMed2002

Control of witchweed Striga hermonthica by intercropping with Desmodium spp., and the mechanism defined as allelopathic.

During investigations into the control of insect damage to maize crops in subsistence farming in Kenya, which involved intercropping with repellent plants, the fodder legumes silverleaf (Desmodium uncinatum) and greenleaf (D. intortum) were also found to reduce dramatically the infestation of maize by parasitic witchweeds such as Striga hermonthica. This effect was confirmed by further field testing and shown to be significantly greater than that observed with other legumes, e.g., cowpea, as were the concomitant yield increases. The mechanism was investigated, and although soil shading and addition of nitrogen fertilizer showed some benefits against S. hermonthica infestation, a putative allelopathic mechanism for D. uncinatum was observed. In screenhouse studies, a highly significant reduction in S. hermonthica infestation was obtained when an aqueous solution, eluting from pots in which D. uncinatum plants were growing, was used to irrigate pots of maize planted in soil seeded with high levels of S. hermonthica. Growth of the parasitic weed was almost completely suppressed. whereas extensive infestation occurred with the control eluate. Laboratory investigations into the allelopathic effect of D. uncinatum, using samples of water-soluble chemical components exuded from cleaned roots, demonstrated that this involved a germination stimulant for S. hermonthica and also an inhibitor for haustorial development.

Crops, Agricultural↗
PubMed2003

Characterization of nitrogen relationships between Sorghum bicolor and the root-hemiparasitic angiosperm Striga hermonthica (Del.) Benth. using K15 NO3 as isotopic tracer.

The role of the host in the nitrogen nutrition of Striga hermonthica (Del.) Benth. (Scrophulariaceae) parasitic on Sorghum bicolor cv. SH4 Arval has been investigated using (15)N-nitrate as the tracer. It is shown that, when nitrate is absorbed only by the roots of the host plant, a rapid transfer of nitrogen to the parasite can be detected. The xylem sap of S. hermonthica contained approximately equal amounts of nitrate and amino acids, mostly glutamine and asparagine. Infection altered the free amino acid profile of the host tissues, leading notably to a large increase in asparagine and a decrease in glutamine. The haustoria of S. hermonthica, although rich in nitrate, showed a low concentration of free amino acids, particularly lacking in asparagine and glutamine. The roots of S. hermonthica, in contrast, were rich in both asparagine and glutamine while, in the shoots, asparagine constituted 80% of the total FAA pool. Asparagine was also found to be the primary (15)N-enriched amino acid in the shoots of S. hermonthica while, interestingly, it was glutamate that was most strongly enriched in the roots. It is concluded that nitrogen nutrition in S. hermonthica is based on a supply of both nitrate and amino acids from the host. This implies a non-specific transfer in the transpiration stream. Nitrate reduction probably occurs mainly in the leaves of the parasite. Assimilation also occurs in S. hermonthica and excess nitrogen is stored as the non-toxic nitrogen-rich compound, asparagine. This specific trait of nitrogen metabolism of the parasite is discussed in relation to the effect of nitrogen fertilization on reducing infestation.

Algorithms↗
PubMed2006

Impact of nitrate supply in C and N assimilation in the parasitic plant Striga hermonthica (Del.) Benth (Scrophulariaceae) and its host Sorghum bicolor L.

The threshold of tolerance for nitrate of the parasitic weed Striga hermonthica (Del.) Benth and the host plant Sorghum bicolor L. was determined by estimating the impact of increasing nitrate loads on plant growth and various parameters of C and N assimilation. Nitrate supply improved chlorophyll (Chl) content and photosystem II (PSII) photochemistry of infected S. bicolor that, in comparison to S. hermonthica, displayed a low imbalance between C and N assimilation when nitrate was supplied up to 1500 mg N per plant. Indeed, nitrate supplies increased strongly the leaf N:C ratio of the parasite. The higher nitrate load induced strong accumulation of nitrate, nitrite and ammonium, and consequently the death of S. hermonthica. Nevertheless, lower nitrate loads (up to 500 mg N per S. bicolor in this study) promoted leaf expansion, PSII photochemistry and N metabolism of S. hermonthica mature (M) plants, as attested by the significant rise in soluble protein and free amino-acid contents. Following these N supplies, the nitrate tolerance of S. hermonthica was correlated with an increase in PSII activity and a high incorporation of N excess into asparagine. This confirmed the central role of asparagine in the N metabolism of S. hermonthica, although this detoxification pathway was insufficient to limit ammonium accumulation under higher nitrate loads.

Asparagine↗
PubMed2005

Confirmation and quantification of strigolactones, germination stimulants for root parasitic plants Striga and Orobanche, produced by cotton.

The germination stimulants for root parasitic plants Striga and Orobanche produced by cotton (Gossypium hirsutum L.) were examined in detail. Seeds of cotton were germinated and grown on glass wool wetted with sterile distilled water in sterile filter units. The root exudate was collected daily and extracted with ethyl acetate. Each of these ethyl acetate extracts was analyzed directly by high-performance liquid chromatography linked with tandem mass spectrometry (LC/MS/MS). The results demonstrate that cotton roots exuded strigol and strigyl acetate, but no other known strigolactones such as orobanchol and alectrol. The production of strigol was detected even in the root exudate collected during the first 24 h of incubation and reached a maximum 5-7 days later. The average exudation of strigol and strigyl acetate during the incubation period was ca. 15 and 2 pg/plant/day, respectively, indicating that strigol mainly contributed to germination stimulation by the cotton root exudate.

Germination↗
PubMed2004

In vitro and in vivo antimalarial studies of Striga hermonthica and Tapinanthus sessilifolius extracts.

The antimalarial activities of the methanol extracts of Striga hermonthica (whole plant) and Tapinanthus sessilifolius (leaves), commonly used in Northern Nigeria for the treatment of malaria, were evaluated. In the in vitro antiplasmodial analysis, the extracts of T. sessilifolius and S. hermonthica utilized in the study, displayed mild to weak activities with IC50 values of 200.5 and 274.8 microg/ml respectively. This was investigated, using the multidrug resistant Plasmodium falciparum, K1 strain, in the parasite lactate dehydrogenase assay. The murine model in vivo antimalarial activity of the tested extracts, using chloroquine-sensitive Plasmodium berghei (ANKA P1), in the 4-day suppressive test, showed that both plants had intrinsic antimalarial properties, that were dose-dependent. At a dose of 400mg/kg weight of mice, extract of S. hermonthica exhibited a higher intrinsic antimalarial activity (68.5 % suppression) than that of T. sessilifolius (51.3 %). Chloroquine, the standard reference drug, had an average suppression of 78.0 % at a dose of 10 mg/kg weight of mice while normal saline was used as control. Preliminary phytochemical screening of the extracts indicated the presence ofsaponins, tannins, flavonoids, volatile oils and cardiac glycosides.

Animals↗
PubMed2000

Antifertility and hormonal properties of flavones of Striga orobanchioides.

The two flavones, apigenin and luteolin, isolated from Striga orobanchioides, were investigated for endocrine and contraceptive properties. Graded doses of these compounds (5-25 mg/kg body weight/day) when administered from day 1 to day 4 of pregnancy showed dose-dependent and significant anti-implantation activity. The mean effective Dose 100% (MED(100)) for both compounds was found to be 25 mg/kg body weight. Oral administration of these compounds caused a significant increase in uterine weight in immature ovariectomised rats. It also caused a significant increase in uterine diameter, thickness of the endometrium and its epithelial cell height when compared with those of control rats. The uterotrophic potency was less than that of ethinyl estradiol. Simultaneous administration of these compounds with ethinyl estradiol caused a significant increase in uterine weight, uterine diameter, thickness of the endometrium and height of endometrial epithelium. The extent of these changes was also less than that in only ethinyl estradiol-treated rats. Hence the compounds exhibited estrogenic properties at their contraceptive dose level when given alone. However, along with ethinyl estradiol, they exhibited slight anti-estrogenic activity.

Animals↗
PubMed1997

Antiandrogenic effect of Striga orobanchioides.

The ethanolic extract of the whole plant of Striga orobanchioides given for 7 days to immature male rats at a dose level of 200 mg/kg body weight caused a significant decrease in the weight of the testes, epididymis, seminal vesicles and the ventral prostate. It also produced degenerative changes of Leydig cells, their nucleus, the seminiferous tubules and a significant decrease in the number of spermatocytes and spermatids. The seminiferous tubules of the treated rats are shrunken and compactly arranged. The antiandrogenic or antispermatogenic effect of the extract is discussed.

Androgen Antagonists↗
PubMed1999

Dose-response of seeds of the parasitic weeds Striga and Orobanche toward the synthetic germination stimulants GR 24 and Nijmegen 1.

Striga and Orobanche seeds germinate in response to a host-derived germination stimulant. Dose-response curves of the synthetic strigolactone analogues GR 24 and Nijmegen 1 were determined, and their activities were compared to that of the naturally occurring stimulant sorgolactone. Typical sigmoidal curves were obtained. ED(50) values for GR 24 were in the order of 10(-)(9)-10(-)(8) mol/L; for Nijmegen 1 these values were 3 orders of magnitude higher. Both synthetic stimulants are appreciably active at low concentrations and merit investigation as agents for the suicidal germination approach (i.e., treatment of the soil with stimulant in the absence of a host).

Dose-Response Relationship, Drug↗
PubMed1990

Vegetative/Parasitic transition: control and plasticity in striga development.

Striga asiatica (Scrophulariaceae), an obligate parasite of grasses including many of the world's major grain crops, switches from vegetative to parasitic development by the differentiation of the root meristem into the host attachment organ, the haustorium. This change was induced in culture by the exposure to a single, low molecular weight signal molecule, 2,6-dimethoxy-p-benzo-quinone. A concentration of 10(-6) molar quinone and an exposure time of >/=6 hours were required before the developmental process could be completed. With shorter exposure times, haustorial development was prematurely aborted and meristematic elongation was reestablished. The new meristem was capable of developing a second haustorium if reexposed to the signal molecule. These results are discussed in terms of the transition to the parasitic phase and the general control of plant cellular development.

Journal Article↗
PubMed1994

Antifertility activity of Striga orobanchioides.

Four successive solvent extracts of the whole plant Striga orobanchioides have been screened for antifertility activity in albino rats. Of these the ethanolic extract was found to be most effective in causing significant anti-implantation activity. The antifertility activity was reversible on withdrawal of treatment with the extract. The ethanolic extract at 200 mg/kg showed estrogenic activity. Histological studies of the uterus were carried out to confirm this estrogenic activity.

Animals↗
PubMed1990

Antifertility activity of striga lutea--Part I.

The petroleum ether and chloroform extracts of the whole plant striga lutea have been found to possess significant antifertility activity in mice. Both these extract exhibited complete and partial resorption of implants at a dose of 100 mg/kg and 50 mg/kg body weight, respectively. Histological studies of the uterus and ovary were carried out to confirm the antifertility activity of these extracts.

Animals↗
PubMed1990

Antifertility efficacy of the plant Striga lutea (Scrophulariacae) on rats.

Acacetin and luteolin, the flavones isolated from the whole plant S. lutea, have been investigated for endocrine and contraceptive properties in the pre-implantation stage of pregnancy. Graded doses of these compounds, in gum acacia suspension, by oral administration from day 1 to day 4 of pregnancy showed dose-dependent anti-implantation activity (5-25 mg/kg body weight/day). MED100 was found to be 25 mg/kg body weight in the day 1-4 regimen in rats for both the compounds. In another study, a single oral dose of these compounds (10 mg/kg body weight) on day 1, 2 or 3 of pregnancy prevented 100% implantation. The compounds exhibited estrogenic property at their contraceptive dose level but failed to show antiestrogenic activity.

Animals↗
PubMed2001

Antihistaminic and mast cell stabilizing activity of Striga orobanchioides.

The ethanolic and aqueous extracts of the whole plant of S. orobanchioides were evaluated for antihistaminic and mast cell stabilizing activities. Both extracts inhibited histamine-induced contractions of the guinea-pig ileum at the concentration range of 2.5-25 microg/ml in a dose-related manner. At 25 microg/ml, both extracts inhibited the response of histamine (0.5 microg/ml) almost completely. The effect of these two extracts on the degranulation rate of sensitized peritoneal cells of albino rats when challenged with antigen (horse serum) was studied. Triple vaccine was used as adjuvant. Ketotifen and prednisolone were used for comparison. The ethanolic extract at 100 and 200 mg/kg body weight was found to significantly inhibit degranulation of mast cells to an extent of 52.14+/-3.24 and 67.96+/-3.70%, respectively. At the same doses, the aqueous extract showed 42.09+/-2.91 and 60.67+/-3.50% reduction in degranulation of mast cells, respectively. Hence, both extracts markedly protected the rats against antigen-induced challenge of mast cells.

Administration, Oral↗