Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Differential Activity of Striga hermonthica Seed Germination Stimulants and Gigaspora rosea Hyphal Branching Factors in Rice and Their Contribution to Underground Communication
Cardoso, C. ; Charnikhova, T. ; Jamil, M. ; Delaux, P.M. ; Verstappen, F.W.A. ; Amini, M. ; Lauressergues, D. ; Ruyter-Spira, C.P. ; Bouwmeester, H.J. - \ 2014
PLoS ONE 9 (2014)8. - ISSN 1932-6203
arbuscular mycorrhizal fungi - strigolactone production - structural requirements - phosphorus deficiency - phosphate deficiency - gesnerioides seeds - plant hormones - root parasites - red-clover - inhibition
Strigolactones (SLs) trigger germination of parasitic plant seeds and hyphal branching of symbiotic arbuscular mycorrhizal (AM) fungi. There is extensive structural variation in SLs and plants usually produce blends of different SLs. The structural variation among natural SLs has been shown to impact their biological activity as hyphal branching and parasitic plant seed germination stimulants. In this study, rice root exudates were fractioned by HPLC. The resulting fractions were analyzed by MRM-LC-MS to investigate the presence of SLs and tested using bioassays to assess their Striga hermonthica seed germination and Gigaspora rosea hyphal branching stimulatory activities. A substantial number of active fractions were revealed often with very different effect on seed germination and hyphal branching. Fractions containing (-)-orobanchol and ent-2'-epi-5-deoxystrigol contributed little to the induction of S. hermonthica seed germination but strongly stimulated AM fungal hyphal branching. Three SLs in one fraction, putative methoxy-5-deoxystrigol isomers, had moderate seed germination and hyphal branching inducing activity. Two fractions contained strong germination stimulants but displayed only modest hyphal branching activity. We provide evidence that these stimulants are likely SLs although no SL-representative masses could be detected using MRM-LC-MS. Our results show that seed germination and hyphal branching are induced to very different extents by the various SLs (or other stimulants) present in rice root exudates. We propose that the development of rice varieties with different SL composition is a promising strategy to reduce parasitic plant infestation while maintaining symbiosis with AM fungi.
New strigolactone mimics: structure-activity relationship and mode of action as germinating stimulants for parasitic weeds.
Zwanenburg, B. ; Nayak, S.K. ; Charnikhova, T. ; Bouwmeester, H.J. - \ 2013
Bioorganic and Medicinal Chemistry Letters 23 (2013)18. - ISSN 0960-894X - p. 5182 - 5186.
seed-germination - orobanche-minor - plant hormones - am fungi - striga-hermonthica - red-clover - analogs - inhibition - ring - phelipanche
Strigolactones (SLs) are new plant hormones with varies important bio-functions. This Letter deals with germination of seeds of parasitic weeds. Natural SLs have a too complex structure for synthesis. Therefore, there is an active search for SL analogues and mimics with a simpler structure with retention of activity. SL analogues all contain the D-ring connected with an enone moiety through an enol ether unit. A new mechanism for the hydrolysis SL analogues involving bidentate bound water and an a,ß-hydrolase with a Ser-His-Asp catalytic triad has been proposed. Newly discovered SL mimics only have the D-ring with an appropriate leaving group at C-5. A mode of action for SL mimics was proposed for which now supporting evidence is provided. As predicted an extra methyl group at C-4 of the D-ring blocks the germination of seeds of parasitic weeds.
Strigolactone Biosynthesis in Medicago truncatula and Rice Requires the Symbiotic GRAS-Type Transcription Factors NSP1 and NSP2
Liu, W. ; Kohlen, W. ; Lillo, A. ; Camp, R. op den; Ivanov, S. ; Hartog, M. ; Limpens, E.H.M. ; Jamil, M. ; Smaczniak, C. ; Kaufmann, K. ; Yang, W.C. ; Hooiveld, G.J.E.J. ; Charnikhova, T. ; Bouwmeester, H.J. ; Bisseling, T. ; Geurts, R. - \ 2011
The Plant Cell 23 (2011)10. - ISSN 1040-4651 - p. 3853 - 3865.
arbuscular mycorrhizal fungi - affymetrix genechip data - tiller bud outgrowth - quality assessment - lotus-japonicus - germination stimulants - transduction pathway - phosphate deficiency - parasitic plants - red-clover
Legume GRAS (GAI, RGA, SCR)-type transcription factors NODULATION SIGNALING PATHWAY1 (NSP1) and NSP2 are essential for rhizobium Nod factor-induced nodulation. Both proteins are considered to be Nod factor response factors regulating gene expression after symbiotic signaling. However, legume NSP1 and NSP2 can be functionally replaced by nonlegume orthologs, including rice (Oryza sativa) NSP1 and NSP2, indicating that both proteins are functionally conserved in higher plants. Here, we show that NSP1 and NSP2 are indispensable for strigolactone (SL) biosynthesis in the legume Medicago truncatula and in rice. Mutant nsp1 plants do not produce SLs, whereas in M. truncatula, NSP2 is essential for conversion of orobanchol into didehydro-orobanchol, which is the main SL produced by this species. The disturbed SL biosynthesis in nsp1 nsp2 mutant backgrounds correlates with reduced expression of DWARF27, a gene essential for SL biosynthesis. Rice and M. truncatula represent distinct phylogenetic lineages that split approximately 150 million years ago. Therefore, we conclude that regulation of SL biosynthesis by NSP1 and NSP2 is an ancestral function conserved in higher plants. NSP1 and NSP2 are single-copy genes in legumes, which implies that both proteins fulfill dual regulatory functions to control downstream targets after rhizobium-induced signaling as well as SL biosynthesis in nonsymbiotic conditions.
Tomato strigolactones are derived from carotenoids and their biosynthesis is promoted by phosphate starvation
Lopez Raez, J.A. ; Charnikhova, T. ; Gomez-Roldan, M.V. ; Matusova, R. ; Kohlen, W. ; Vos, C.H. de; Verstappen, F.W.A. ; Puech-Pages, V. ; Becard, G. ; Mulder, P.P.J. ; Bouwmeester, H.J. - \ 2008
New Phytologist 178 (2008)4. - ISSN 0028-646X - p. 863 - 874.
arbuscular mycorrhizal fungi - root parasitic plants - germination stimulants - abscisic-acid - red-clover - orobanche - striga - weeds - maize - manipulation
Strigolactones are rhizosphere signalling compounds that mediate host location in arbuscular mycorrhizal (AM) fungi and parasitic plants. Here, the regulation of the biosynthesis of strigolactones is studied in tomato (Solanum lycopersicum). Strigolactone production under phosphate starvation, in the presence of the carotenoid biosynthesis inhibitor fluridone and in the abscisic acid (ABA) mutant notabilis were assessed using a germination bioassay with seeds of Orobanche ramosa; a hyphal branching assay with Gigaspora spp; and by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) analysis. The root exudates of tomato cv. MoneyMaker induced O. ramosa seed germination and hyphal branching in AM fungi. Phosphate starvation markedly increased, and fluridone strongly decreased, this activity. Exudates of notabilis induced approx. 40% less germination than the wild-type. The LC-MS/MS analysis confirmed that the biological activity and changes therein were due to the presence of several strigolactones; orobanchol, solanacol and two or three didehydro-orobanchol isomers. These results show that the AM branching factors and parasitic plant germination stimulants in tomato root exudate are strigolactones and that they are biosynthetically derived from carotenoids. The dual activity of these signalling compounds in attracting beneficial AM fungi and detrimental parasitic plants is further strengthened by environmental conditions such as phosphate availability.
Isolated Isoflavones do not affect the circulating insulin-like growth factor system in men at increased colorectal cancer risk
Vrieling, A. ; Rookus, M.A. ; Kampman, E. ; Bonfrer, J.M.G. ; Korse, C.M. ; Doorn, J. van; Lampe, J.W. ; Cats, A. ; Witteman, B.J.M. ; Leeuwen, F.E. van; van't Veer, L.J. ; Voskuil, D.W. - \ 2007
The Journal of Nutrition 137 (2007)2. - ISSN 0022-3166 - p. 379 - 383.
estrogen replacement therapy - red-clover - factor-i - postmenopausal women - binding protein-3 - soy protein - clinical characteristics - premenopausal women - antioxidant status - human health
Epidemiological studies show that increased insulin-like growth factor (IGF)-I concentrations are related to increased colorectal cancer risk. A reduced colorectal cancer risk has been associated with isoflavones, which might affect the IGF-system because of their weak estrogenic activity. We conducted a randomized, placebo-controlled, double-blind crossover study to investigate the effect of an 8-wk isolated isoflavone supplementation (84 mg/d) on serum concentrations of total IGF-I, free IGF-I, total IGF-II, IGF binding protein (BP)-1, IGFBP-2, and IGFBP-3. Additionally, we investigated whether IGF-system component differences were related to concentrations of the more potent estrogenic isoflavone metabolite, equol. Our study population consisted of 37 men with a family history of colorectal cancer or a personal history of colorectal adenomas. Isoflavone supplementation did not significantly affect serum total IGF-I concentrations (relative difference between serum total IGF-I concentrations after isoflavone supplementation and after placebo: ¿1.3%, 95% CI ¿8.6 to 6.0%). Neither free IGF-I, nor total IGF-II, IGFBP-1, IGFBP-2, or IGFBP-3 concentrations were significantly altered. Interestingly, the change in serum IGF-I concentrations after isoflavone supplementation was negatively associated with serum equol concentrations (r = ¿0.49, P = 0.002). In conclusion, isolated isoflavones did not affect the circulating IGF-system in a male high-risk population for colorectal cancer. However, to our knowledge, this is the first study that suggests isoflavones might have an IGF-I lowering effect in equol producers only. This underlines the importance of taking into account equol status in future isoflavone intervention studies
Voluntary intake of silages in dairy cows depending on chemical composition and in vitro gas production characteristics
Hetta, M. ; Cone, J.W. ; Bernes, G. ; Gustavsson, A.M. ; Martinsson, K. - \ 2007
Livestock Science 106 (2007)1. - ISSN 1871-1413 - p. 47 - 56.
rumen fermentation characteristics - nylon bag degradability - neutral detergent fiber - grass-silage - production profiles - ruminant feeds - food-intake - red-clover - prediction - digestion
A study was conducted to investigate the possibilities to develop models for predicting the relative silage dry matter intake (SDMI) in dairy cows utilising information on chemical composition and in vitro gas production (GP) kinetics of silages. In five experiments, each with an average of 38 lactating dairy cows, SDMI was recorded for 15 grass silages made from primary growth and regrowth swards of timothy (Phleum pratense L.). The silages were characterised by chemical analysis and by utilising an automated in vitro GP recording technique with end point measurements of substrate residues. The silage samples were analysed both as dried and wet samples to evaluate the effects of sample preparation techniques on GP kinetics and their relations to SDMI. Relationships between feed variables and SDMI were investigated utilising simple linear and multiple regression. The wet silage samples had higher cumulative GP and different GP curves compared to the dried samples. The linear relationships between, GP variables, harvest number (first or second cut) of the grass, chemical characteristics of the silages and the relative SDMI show that the GP technique is a powerful tool to detect silage quality. By using the parameters from the dried samples the multiple regression analysis resulted in a relationship, relative SDMI (kg per 100 kg live weight (LW)) per day=0.071+0.0029 x NDFD-0.266 x C (R-2 =0.82, S.D.=0.06). NDFD is the degradability of the neutral detergent fibre (NDF) (g/kg NDF) and C is the variable that regulates the switching characteristics of the GP profiles. By using the wet silage samples the multiple relationship did not include any GP variable; relative SDMI (kg per 100 kg LW per day) = 1.86-0.008 x acetic acid (g/kg DM) + 0.024 x ethanol (g/kg DM) (R-2=0.62, S.D.=0.08). The results from the regression analysis and the experience of the laborious sample preparation technique for wet samples, give the conclusion that dried silage samples are recommended for determining feed characteristics using the GP technique in intake studies. (c) 2006 Published by Elsevier B.V.
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