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production of oxalic acid by some fungi infected tubers.oxalic acid (as oxalate) was detected in four tubers commonly used for food in nigeria-dioscorea rotundata (white yam), solanum tuberosum (irish potato), ipomoea batatas (sweet potato), and manihot esculenta (cassava). whereas healthy i. batata had the highest oxalic acid content, healthy m. esculenta contained the lowest. when all tubers were artifically inoculated with four fungi-penicillium oxalicum curie and thom, aspergillus niger van tiegh, a. flavus and a. tamarii kita, there was an incre ...19836670294
biocontrol and other beneficial activities of bacillus subtilis isolated from cowdung microflora.bacillus subtilis strains isolated from cowdung (cd) had several beneficial attributes, which included biocontrol, plant growth promotion, sulphur (s) oxidation, phosphorus (p) solubilization and production of industrially important enzymes (amylase and cellulase). the b. subtilis strains from cd inhibited the in vitro growth of fungi, fusarium oxysporum (25-34%) and botryodiplodia theobromae (100%), isolated from the postharvest rots of yam (dioscorea rotundata) tubers. other than biocontrol, b ...200917320363
biocontrol efficacy of bacillus subtilis strains isolated from cow dung against postharvest yam (dioscorea rotundata l.) pathogens.the biocontrol potential of bacillus subtilis isolated from cow dung microflora was investigated in vitro and in vivo against two postharvest yam pathogenic fungi, fusarium oxysporum and botryodiplodia theobromae. b. subtilis strains inhibited the growth of f. oxysporum and b. theobromae in vitro in liquid medium in the range of 49.3-56.6% and in solid medium in the range of 31.0-36.0%, in comparison to the corresponding growth of fungi without bacterial inoculation. the interaction between b. s ...200818663522
permanent genetic resources added to molecular ecology resources database 1 june 2010 - 31 july 2010.this article documents the addition of 205 microsatellite marker loci to the molecular ecology resources database. loci were developed for the following species: bagassa guianensis, bulweria bulwerii, camelus bactrianus, chaenogobius annularis, creontiades dilutus, diachasmimorpha tryoni, dioscorea alata, euhrychiopsis lecontei, gmelina arborea, haliotis discus hannai, hirtella physophora, melanaphis sacchari, munida isos, thaumastocoris peregrinus and tuberolachnus salignus. these loci were cro ...201021565125
indole-3-acetic acid production and effect on sprouting of yam (dioscorea rotundata l.) minisetts by bacillus subtilis isolated from culturable cowdung microflora.bacillus subtilis strains (cm1-cm5) isolated from culturable cowdung microflora were investigated for indole-3-acetic acid (iaa) production in nutrient broth (nb). all the strains tested produced iaa in nb; albeit in very low concentrations (0.09-0.37 mg/l). the addition of l-tryptophan (0.1 - 1.0 g/l) into nb substantially enhanced iaa production (6.1 - 31.5 folds) indicating that l-tryptophan was the precursor for iaa biosynthesis by these bacterial strains. maximum iaa production was observed ...200717650680
food processing methods influence the glycaemic indices of some commonly eaten west indian carbohydrate-rich foods.glycaemic index (gi) values for fourteen commonly eaten carbohydrate-rich foods processed by various methods were determined using ten healthy subjects. the foods studied were round leaf yellow yam (dioscorea cayenensis), negro and lucea yams (dioscorea rotundata), white and sweet yams (dioscorea alata), sweet potato (solanum tuberosum), irish potato (ipomoea batatas), coco yam (xanthosoma spp.), dasheen (colocasia esculenta), pumpkin (cucurbita moschata), breadfruit (artocarpus altilis), green ...200616925852
fermentation of yam: microbiology and sensory evaluation of cooked fermented yam tissues.the microflora of white yam (dioscorea rotundata l.) slices fermented anaerobically in 1.5 percent brine for five days at room temperature were studied. the hydrolysis of the carbohydrate and the subsequent conversion of sugars and minerals by the fermenting microbes contributed much to the increased microbial load especially within the first 72 hours of fermentation. the organisms implicated in the fermentation include the species of pediococcus, lactobacillus and pseudomonas, bacillus subtilis ...19989839834
dietary exposure to aflatoxin in benin city, nigeria: a possible public health concern.a total of 100 samples of various foods comprising of 10 samples each of garri (manihot utilis pohl), beans (phaseolus lunatus), yam flour (dioscorea rotundata), cassava flour (manihot esculentum), melon (citrulus lunatus), onion (allium cepa), rice (oryza sativa), plantain (musa paradisiaca), red pepper (capsicum annuum l., solanaceae) and eggs were screened for the presence of aflatoxins. fifty percent of yam flour; 40% of cassava flour; 30% of garri; 20% of beans and melon and 10% of rice yie ...19911777386
monitoring microbiological and biochemical changes in fermented yam.the microbiological and biochemical changes occurring in yam (dioscorea rotundata l.) tissues fermented in 2% brine under anaerobic conditions at ambient temperature were studied. the ash. fibre and fat contents of the yam tissues were reduced at an average rate of 1.98, 1.72 and 0.42 mg g(-1) d(-1), respectively.lactobacillus andleuconostoc spp., as well as other fermentative microorganisms, showed a tendency to increased growth. the decrease in the total aerobic count after a 4-d fermentation ...199718454335
efficacy of oryza sativa husk and quercus phillyraeoides extracts for the in vitro and in vivo control of fungal rot disease of white yam (dioscorea rotundata poir).tuber rot disease is a major constraint to white yam (dioscorea rotundata) production, accounting for 50-60% of annual yield losses in nigeria. the main method of control using synthetic fungicides is being discouraged due to human and environmental health hazards. the potential of oryza sativa husk (osh) and quercus phillyraeoides (qp) extracts for the in vitro and in vivo control of six virulent rot-causing fungal pathogens, lasiodiplodia theobromae, aspergillus niger, rhizoctonia solani, peni ...201425674452
effects of pratylenchus coffeae and scutellonema bradys alone and in combination on guinea yam (dioscorea rotundata).when guinea yam, dioscorea rotundata poir, was inoculated with pratylenchus coffeae and scutellonema bradys together, there was a 53% suppression of top growth, but when plants were inoculated separately there was a 29% suppression with p. coffeae and a 21% suppression with s. bradys. the reproduction of s. bradys was greatly inhibited when both nematode species were together on the same plant in comparison with that on plants inoculated with s. bradys alone. scutellonema bradys apparently did n ...197619308239
pathogenicity of pratylenchus coffeae, scutellonema bradys, meloidogyne incognita, and rotylenchus reniformis on dioscorea rotundata.low populations (200 specimens per plant) of pratylenchus cofl'eae, scutellonema bradys, meloidogyne incognita, and rotylenchulus reniformis stimulated the development of tops, roots, and tubers of dioscorea rotundata "guinea" yam. we demonstrated experimentally that p. coffeae was responsible for the deterioration in quality of the yam tuber in puerto rico, a condition known as a dry rot of yam. initial populations of 600 p. coffeae, s. bradys, or m. incognita, and populations of 1,000 p. coffe ...197519308127
effect of steam pressure treatment on the physicochemical properties of dioscorea starches.dioscorea alata and dioscorea rotundata starches were subjected to steam pressure treatments (0.35, 0.7, and 1.05 kg cm(-)(2)) for different periods. the total amylose content in the treated starches was not significantly affected, but the soluble amylose content decreased 3-5-fold. reducing values and lambda(max) of the iodine complexes were unaffected. viscosity of the starch paste was reduced by the treatments, and at higher pressures and longer time of treatments, the peak viscosity values w ...199910564040
high genetic diversity, distant phylogenetic relationships and intraspecies recombination events among natural populations of yam mosaic virus: a contribution to understanding potyvirus evolution.to evaluate the genetic diversity and understand the evolution of yam mosaic virus (ymv), a highly destructive pathogen of yam (dioscorea sp.), sequencing was carried out of the c-terminal part of the replicase (nib), the coat protein (cp) and the 3'-untranslated region (3'-utr) of 27 ymv isolates collected from the three main cultivated species (dioscorea alata, the complex dioscorea cayenensis-dioscorea rotundata and dioscorea trifida). ymv showed the most variable cp relative to eight other p ...200010640564
spatial distribution of total phenolic content, enzymatic activities and browning in white yam (dioscorea rotundata) tubers.browning in raw and processed yams resulting from enzymes, polyphenol oxidase (ppo) and peroxidase (pod), activities is a major limitation to the industrial utilization of dioscorea varieties of yams. two elite cultivars of d. rotundata species were selected to study the spatial distribution of total phenols and enzymes (ppo and pod) activities. the intensities of tissue darkening in fresh yam chips prepared from the tuber sections of cultivars during frozen storage were also studied. total phen ...201425328234
use of cpssrs for the characterisation of yam phylogeny in benin.the dioscorea cayenensis - dioscorea rotundata species complex is the most widely cultivated yam in west africa. this species complex has been described as deriving from wild yams belonging to the enanthiophyllum section through domestication by african farmers. to study patterns of yam evolution and to establish phylogenetic relationships existing between wild and cultivated species sampled in benin, we investigated changes in chloroplast dna simple sequence repeats (cpssr) in 148 yam accession ...200516094435
segregation patterns of isozyme loci and microsatellite markers show the diploidy of african yam dioscorea rotundata (2n = 40).the cultivated yam species dioscorea rotundata (2n = 40) has been considered by most authors as a tetraploid species with a basic chromosome number of ten. in this paper, we analysed the segregation of two isozyme loci and six microsatellite markers in the progeny of a self-fertilised monoecious plant. for the eight markers, segregation patterns could be explained by only two genetic models: diploidy or tetraploidy with two null alleles. given the nature of studied markers, the most parsimonious ...200515931507
molecular marker based taxonomy and phylogeny of guinea yam (dioscorea rotundata - d. cayenensis).four different molecular techniques were used to assess relationships among 21 accessions of guinea yam (dioscorea rotundata and dioscorea cayenensis) and 21 accessions belonging to seven putative progenitor species. random amplified polymorphic dna (rapd) and microsatellite-primed pcr (mp-pcr) analysis yielded 246 informative characters that were transformed into a matrix of pairwise distances and analyzed by neighbor joining or split decomposition. both methods gave congruent results. well-sep ...199718464876
promiscuous arbuscular mycorrhizal symbiosis of yam (dioscorea spp.), a key staple crop in west africa.yam (dioscorea spp.) is a tuberous staple food crop of major importance in the sub-saharan savannas of west africa. optimal yields commonly are obtained only in the first year following slash-and-burn in the shifting cultivation systems. it appears that the yield decline in subsequent years is not merely caused by soil nutrient depletion but might be due to a loss of the beneficial soil microflora, including arbuscular mycorrhizal fungi (amf), associated with tropical "tree-aspect" savannas and ...200919343374
agrobacterium-mediated genetic transformation of yam (dioscorea rotundata): an important tool for functional study of genes and crop improvement.although genetic transformation of clonally propagated crops has been widely studied as a tool for crop improvement and as a vital part of the development of functional genomics resources, there has been no report of any existing agrobacterium-mediated transformation of yam (dioscorea spp.) with evidence of stable integration of t-dna. yam is an important crop in the tropics and subtropics providing food security and income to over 300 million people. however, yam production remains constrained ...201425309562
microwave and blanch-assisted drying of white yam (dioscorea rotundata).the effect of microwave and blanch pretreatments on the drying kinetics and quality of white yam (dioscorea rotundata) was investigated. yam cubes destined for hot air drying at temperatures 70-90°c were predried in a domestic microwave or blanched in hot water for 1-5 min. microwave pretreatment time had a positive significant effect on drying rate but both pretreatments had a negative influence on the ascorbic acid content and the nonenzymatic browning. the optimum drying conditions were a mic ...201526788300
design of bilayer tablets using modified dioscorea starches as novel excipients for immediate and sustained release of aceclofenac sodium.bilayer tablets of aceclofenac sodium were developed using carboxymethylated white yam (dioscorea rotundata) starch (cwy) for a fast release layer (2.5, 5.0, and 7.5% w/w), and acid-hydrolyzed bitter yam (dioscorea dumetorum) starch (aby) for a sustaining layer (27% w/w). sodium starch glycolate (ssg) and hydroxypropyl methyl cellulose (hpmc) were used as standards. the starches were characterized using fourier transform infrared spectroscopy (ft-ir), particle size, swelling power, densities and ...201425628566
cryopreservation of dioscorea rotundata poir.: a comparative study with two cryogenic procedures and assessment of true-to-type of regenerants by rapd analysis.the aim of this study was to develop a cryopreservation protocol for dioscorea rotundata with maintenance of genetic stability of regenerated plants after cryopreservation. in vitro shoot tips were cryopreserved using vitrification and encapsulation-dehydration to compare the efficacy of the two methods. both methods produced high levels of plant regeneration from cryopreserved shoot tips. the regeneration level obtained using vitrification (71%) was not significantly different from that obtaine ...200818946554
changes in biochemical constituents and induction of early sprouting by triadimefon treatment in white yam (dioscorea rotundata poir.) tubers during storage.the ability of triadimefon (tdm), a triazolic fungicide, to alter the biochemical constituents and thereby minimizing the days required for sprouting in white yam (dioscorea rotundata poir.) tubers during storage under (30+/-2) degrees c in the dark, was studied. tdm at 20 mg/l was given to tubers by dipping the tubers in treatment solution containing 20 mg/l tdm on 10, 25 and 40 d after storage (das). starch, sugars, protein, amino acid contents as well as protease and alpha-amylase activities ...200717444605
biochemical origin of browning during the processing of fresh yam (dioscorea spp.) into dried product.this study was undertaken to follow the kinetics of polyphenoloxidase (ppo), peroxidase (pod), and phenolic compounds during yam blanching at different temperatures and after drying and to identify by high-performance liquid chromatography (hplc) the main phenolic compounds present in yam products. ppo activity was 50% higher in nonprocessed freeze-dried florido (dioscorea alata) than in nonprocessed freeze-dried deba (dioscorea rotundata). it decreased progressively during blanching. forty-five ...200515796594
evaluation of starches obtained from four dioscorea species as binding agent in chloroquine phosphate tablet formulations.starches obtained from four dioscorea species namely dioscorea dumetorum (bitter), dioscorea oppositifolia (chinese), dioscorea alata (water), and dioscorea rotundata (white) have been evaluated as binding agents in chloroquine phosphate tablet formulations in comparison with official corn starch. the compressional properties of the formulations were analyzed using density measurements and the heckel and kawakita equations. the mechanical properties of the tablets were assessed using tensile str ...201123960747
potential health benefits of water yam (dioscorea alata).yam is the third most important root and tuber crop in the tropics but few species are grown as health food and/or for medicinal purposes. to ascertain the potential health benefits and alternate usage of the species, 20 varieties of dioscorea alata (water yam) were investigated for their total dietary fiber (tdf), dry matter and amylose contents as well as selected minerals in comparison with dioscorea rotundata, the preferred species in yam-growing areas. the tdf content varied widely ranging ...201324056383
a sequence-independent strategy for amplification and characterisation of episomal badnavirus sequences reveals three previously uncharacterised yam badnaviruses.yam (dioscorea spp.) plants are potentially hosts to a diverse range of badnavirus species (genus badnavirus, family caulimoviridae), but their detection is complicated by the existence of integrated badnavirus sequences in some yam genomes. to date, only two badnavirus genomes have been characterised, namely, dioscorea bacilliform al virus (dbalv) and dioscorea bacilliform sn virus (dbsnv). a further 10 tentative species in yam have been described based on their partial reverse transcriptase (r ...201627399761
biochemical changes occurring during growth and storage of two yam species.the biochemical changes occurring during growth and storage of two yam cultivars (dioscorea rotundata cv. oshei and dioscorea dumetorum cv. jakri) were studied. tubers were harvested at monthly intervals from the fourth to the tenth month after 50% emergence of the planted yam sets. for storage studies, oshei and jakri tubers were harvested 9.5 and 9 months post-emergence, respectively. these were stored under prevailing tropical ambient conditions (18-31 degrees c, 62-100% rh) for 1,2,3 and 4 m ...19968833173
phases of dormancy in yam tubers (dioscorea rotundata).the control of dormancy in yam (disocorea spp.) tubers is poorly understood and attempts to shorten the long dormant period (i.e. cause tubers to sprout or germinate much earlier) have been unsuccessful. the aim of this study was to identify and define the phases of dormancy in dioscorea rotundata tubers, and to produce a framework within which dormancy can be more effectively studied.200616446288
next-generation sequencing based genotyping, cytometry and phenotyping for understanding diversity and evolution of guinea yams.genotyping by sequencing (gbs) is used to understand the origin and domestication of guinea yams, including the contribution of wild relatives and polyploidy events to the cultivated guinea yams. patterns of genetic diversity within and between two cultivated guinea yams (dioscorea rotundata and d. cayenensis) and five wild relatives (d. praehensilis, d. mangenotiana, d. abyssinica, d. togoensis and d. burkilliana) were investigated using next-generation sequencing (genotyping by sequencing, gbs ...201424981608
effect of the mode of incorporation on the disintegrant properties of acid modified water and white yam starches.acid modified starches obtained from two species of yam tubers namely white yam - dioscorea rotundata l. and water yam - d. alata l. dial2 have been investigated as intra- and extra-granular disintegrants in paracetamol tablet formulations. the native starches were modified by acid hydrolysis and employed as disintegrant at concentrations of 5 and 10% w/w and their disintegrant properties compared with those of corn starch bp. the tensile strength and drug release properties of the tablets, asse ...201223960789
sucrose treatment and explant water content: critical factors to consider in development of successful cryopreservation protocols for shoot tip explants of the tropical species dioscorea rotundata (yam).a study was conducted to determine the optimum methods for conditioning explants to be used in the development of a simple protocol for long-term conservation of the germplasm of dioscorea rotundata via cryopreservation. shoot tips from cultures maintained in vitro were exposed to high concentrations of sucrose prior to silica gel-based dehydration and vitrification solution-based cryopreservation protocols. explant water contents were determined, and ultrastructural studies were also carried ou ...200919750245
isolation and characterization of microsatellites for the yam dioscorea cayenensis (dioscoreaceae) and cross-amplification in d. rotundata.dioscorea cayenensis and dioscorea rotundata are among the most important yam species for the humid and sub-humid tropics. we isolated nine polymorphic microsatellite markers using a microsatellite-enriched genomic library technique. the nine primer pairs were validated in 22 d. cayenensis accessions, and were tested for transferability in 26 d. rotundata accessions. the number of bands ranged from 2 to 4, with a mean of 3.11. d. cayenensis gave primer polymorphism information content values ran ...201424782090
responses of antioxidant potentials in dioscorea rotundata poir. following paclobutrazol drenching.the effect of paclobutrazol (pbz) treatments on the antioxidant metabolism of white yam (dioscorea rotundata poir.) was investigated in the present study. pbz @ 15 mg l(-1) plant(-1) was given to plants by soil drenching, 30, 60, and 90 days after planting (dap). the non-enzymatic antioxidant contents like ascorbic acid (aa), reduced glutathione (gsh) and alpha-tocopherol (alpha-toc), activities of antioxidant enzymes like superoxide dismutase (sod), ascorbate peroxidase (apx), polyphenol oxidas ...200717923373
clonal diversity and estimation of relative clone age: application to agrobiodiversity of yam (dioscorea rotundata).clonal propagation is a particular reproductive system found in both the plant and animal kingdoms, from human parasites to clonally propagated crops. clonal diversity provides information about plant and animal evolutionary history, i.e. how clones spread, or the age of a particular clone. in plants, this could provide valuable information about agrobiodiversity dynamics and more broadly about the evolutionary history of a particular crop. we studied the evolutionary history of yam, dioscorea r ...201324219837
characterization of an isometric virus isolated from yam (dioscorea rotundata) in nigeria suggests that it belongs to a new species in the genus aureusvirus. 201424085328
evaluation of the material and tablet formation properties of modified forms of dioscorea starches.starches obtained from four different dioscorea species-namely, white yam (dioscorea rotundata), bitter yam (dioscorea dumetorum), chinese yam (dioscorea oppositifolia), and water yam (dioscorea alata)-were modified by cross-linking, hydroxypropylation, and dual modification-cross-linking followed by hydroxypropylation. the physicochemical, material, and tablet properties of the modified starches were investigated with the aim of understanding their properties to determine their potential use fo ...200919832640
cryopreservation for the 'in perpetuity' conservation of yam and cassava genetic resources.cryopreservation via droplet vitrification showed high efficiency for cassava meristems (79 pecent average recovery) when these were excised from in vitro seedlings. the efficiency of the process dropped considerably (to > 23 percent) when meristems were excised from field-grown plants, thus precluding the use of such explants for routine cryobanking. in yam, large disparities were observed in the ability of meristems to produce a shoot after cryopreservation ranging from 0 to 60 percent, depend ...201323625079
quality characteristics and acceptability of 'amala' (yam-based thick paste) as influenced by particle size categorization of yam (dioscorea rotundata) flour.the study was essentially an investigation on the influence of size-categorized yam (dioscorea rotundata) flour on the quality characteristics and acceptability of amala (yam-based thick paste). yam flour was separated into three major particle size categories (i.e. 75-150 µm, 150-300 µm and whole meal [<300 µm]), while the physicochemical properties of each category were evaluated and flour samples finally used to prepare amala. both the protein and ash contents of the yam flours were found to ...201323239762
purification and characterization of invertase inhibitors from dioscorea rotundata tuber.three invertase inhibitors (a), (b) and (c) from dioscorea rotundata tuber were resolved on deae-cellulose ion exchanger. two of the inhibitors, (b) and (c), were proteins and homogenous on polyacrylamide gels mr 21,000 +/- 85 and 26,982 +/- 40/36,307 +/- 50 respectively. the inhibitors (b) and (c) were inactivated at 60 degrees c and had activity-ph optima at 5.2 and 6.4 respectively. (b) and (c) were non competitive inhibitors of invertase from yam and other sources.19921284434
aetiology of yam (dioscorea rotundata) tuber rots held in traditional stores in nigeria: importance of fusarium spp. and yam beetle.the extent and causes of yam (dioscorea rotundata) tuber rots were investigated in igalaland, nigeria. rots were found to be associated with prior physical damage in almost all cases. numerous fungal species were isolated from the infected lesions of which fusarium spp. predominated, not botrydiplodia theobromae as previously reported in other studies. none of the fungi was able to infect undamaged yams in laboratory experiments. the damage was caused by both biotic and abiotic factors of which ...19979352665
variation, heritability and genetic advance of eight characters in white yam.phenotypic and genotypic coefficients of variation, heritability, and genetic advance were estimated for: time to vine emergence, leaf size, leaf virus infection, plant leafiness, shoot height, vine dry weight, number of tubers per hill and tuber yield per hill in white yam (dioscorea rotundata poir.) using plants recently derived from seedlings (sp) as well as those that have been clonally propagated for 3-5 years (cp). estimates for these parameters were much lower in sp than in cp plants. mea ...198324263630
granular nematicides for control of the yam nematode, scutellonema bradys, and relevant residues in raw tubers.four granular nentaticides were evaluated for control of the yam nematode, scutellonema bradys (steiner &lehew) andrassy, on guinea yam, dioscorea rotundata poir, under field conditions prevelant in the tropics. a single application of nematicides (sidedressing) at the rate of 2 kg ai/ha as postplanting treatment at the onset of the rainy season depressed numbers of s. bradys attacking yams during the growing season and significantly increased tuber yields over untreated. the efficacy, based on ...198219295699
the disintegration of yam tuber gamma-glutamyl transpeptidase during tuber storage.as an attempt to understand some aspects of the protein catabolism in the resting yam (dioscorea rotundata) tuber with respect to the storage problems of the tuber, gamma-glutamyl transpeptidase (gamma-gtp) was isolated from healthy tubers after aerobic storage for varying periods. the molecular weight was determined by sds-gel electrophoresis and the activity by spectrophotometry using gamma-glutamyl alpha-naphthylamide as substrate. molecular weight and activity were plotted versus duration of ...19816123212
a genetic linkage map of guinea yam ( dioscorea rotundata poir.) based on aflp markers.a genetic linkage map of the tetraploid white yam ( dioscorea rotundata poir.) was constructed based on 341 co-dominantly scored amplified fragment length polymorphism (aflp) markers segregating in an intraspecific f(1) cross. the f(1) mapping population was produced by crossing a landrace cultivar tdr 93-1 as female parent to a breeding line tdr 87/00211 as the male parent. the marker segregation data were split into maternal and paternal data sets, and separate genetic linkage maps were constr ...200212582485
effects of selected process parameters in extrusion of yam flour (dioscorea rotundata) on physicochemical properties of the extrudates.raw yam (dioscorea rotundata) flour was cooked and extruded in a brabender single-screw laboratory scale extruder. response surface methodology using an incomplete factorial design was applied with various combinations of barrel temperature [100, 125, 150 degrees c], feed moisture content [18, 22, 26%] and screw speed [100, 150, 200 rpm]. initial viscosity at 30 degrees c, water solubility index, expansion and hardness were determined. the highest values of initial viscosity were at the highest ...200010795575
histopathology of root-knot nematode (meloidogyne incognita) infection on white yam (dioscorea rotundata) tubers.white yam tissues naturally and artificially infected with root-knot nematodes were fixed, sectioned, and examined with a microscope. infective second-stage juveniles of meloidogyne incognita penetrated and moved intercellularly within the tuber. feeding sites were always in the ground tissue layer where the vascular tissues are distributed in the tubers. giant cells were always associated with xylem tissue. they were thin walled with dense cytoplasm and multinucleated. the nuclei of the giant c ...198819290181
mycoflora of tuber surface of white yam (dioscorea rotundata poir) and postharvest control of pathogens with bacillus subtilis.bacillus subtilis (enrenberg) cohn was investigated for its antagonistic properties against surface mycoflora of yam (dioscorea rotundata poir) tubers in storage. yam tubers inoculated with a spore suspension of b. subtilis in potato dextrose broth using a knapsack sprayer showed a drastic reduction in the range and number of mycoflora, including pathogens of the tuber surface in contrast to the control tubers, during the five-month storage period in a traditional yam barn. however, b. subtilis ...200312733628
origin and phylogeny of guinea yams as revealed by rflp analysis of chloroplast dna and nuclear ribosomal dna.the origin and phylogeny of the guinea yams, consisting of the white yam (dioscorea rotundata poir.) and the yellow yam (d. cayenensis lamk.), has been investigated. fourteen cultivars of guinea yams were sampled with 12 accessions from seven wild yam species. a total of 26 accessions were surveyed for restriction fragment length polymorphisms (rflp) in chloroplast dna (cpdna) and nuclear ribosomal dna (rdna) using seven restriction endonucleases and various heterologous probes. chloroplast dna ...199224202749
genome sequencing of the staple food crop white guinea yam enables the development of a molecular marker for sex determination.root and tuber crops are a major food source in tropical africa. among these crops are several species in the monocotyledonous genus dioscorea collectively known as yam, a staple tuber crop that contributes enormously to the subsistence and socio-cultural lives of millions of people, principally in west and central africa. yam cultivation is constrained by several factors, and yam can be considered a neglected "orphan" crop that would benefit from crop improvement efforts. however, the lack of g ...201728927400
complete genome sequence of a new member of the genus badnavirus, dioscorea bacilliform rt virus 3, reveals the first evidence of recombination in yam badnaviruses.yams (dioscorea spp.) host a diverse range of badnaviruses (genus badnavirus, family caulimoviridae). the first complete genome sequence of dioscorea bacilliform rt virus 3 (dbrtv3), which belongs to the monophyletic species group k5, is described. this virus is most closely related to dioscorea bacilliform sn virus (dbsnv, group k4) based on a comparison of genome sequences. recombination analysis identified a unique recombination event in dbrtv3, with dbsnv likely to be the major parent and di ...201729134336
molecular basis of african yam domestication: analyses of selection point to root development, starch biosynthesis, and photosynthesis related genes.after cereals, root and tuber crops are the main source of starch in the human diet. starch biosynthesis was certainly a significant target for selection during the domestication of these crops. but domestication of these root and tubers crops is also associated with gigantism of storage organs and changes of habitat.201729025393
characterizing genotypic variation in biochemical composition, anti-nutritional and mineral bioavailability of some nigerian yam (dioscorea spp.) land races.the aim of this study was to characterize 43 genotypes from five yam species [dioscorea rotundata (poir), dioscorea alata (linn), dioscorea bulbifera (linn), dioscorea cayenensis (lam) and dioscorea dumetorum (kunith) pax] which are major land races in nigeria in terms of their chemical composition, nutritional, anti-nutritional and mineral bioavailability. findings showed that there was genotypic variation in terms of chemical composition, mineral profile and bioavailability of the minerals amo ...201829358812
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