Publications

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the potential of a phyllosilicate (palabora vermiculite) as buffer in dairy cattle diets.four rumen-fistulated holstein cows were used to determine the ability of vermiculite to alter rumen fermentation, rumen fluid dilution rate, milk production, and nutrient utilization in a 4 x 4 latin square experiment. treatments consisted of 1) basal diet (70% concentrate:30% eragrostis curvula hay), 2) basal + .6% nahco3 + 1.8% vermiculite, 3) basal + 1.2% nahco3, and 4) basal + 3.6% vermiculite. feed intake and milk production were not affected, but the nahco3 treatments tended to increase m ...19892545754
the behavior of multiple independent managers and ecological traits interact to determine prevalence of weeds.management of damaging invasive plants is often undertaken by multiple decision makers, each managing only a small part of the invader's population. as weeds can move between properties and re-infest eradicated sites from unmanaged sources, the dynamics of multiple decision makers plays a significant role in weed prevalence and invasion risk at the landscape scale. we used a spatially explicit agent-based simulation to determine how individual agent behavior, in concert with weed population ecol ...201323734483
increased apomixis expression concurrent with genetic and epigenetic variation in a newly synthesized eragrostis curvula polyploid.eragrostis curvula includes biotypes reproducing through obligate and facultative apomixis or, rarely, full sexuality. we previously generated a "tetraploid-dihaploid-tetraploid" series of plants consisting of a tetraploid apomictic plant (t), a sexual dihaploid plant (d) and a tetraploid artificial colchiploid (c). initially, plant c was nearly 100% sexual. however, its capacity to form non-reduced embryo sacs dramatically increased over a four year period (2003-2007) to reach levels of 85-90%. ...201424710346
nutritional and sensory evaluation of injera prepared from tef and eragrostis curvula (schrad.) nees. flours with sorghum blends.injera is a fermented, sour bread consumed as a staple food in eritrea and ethiopia. the bread can be prepared from various cereals but tef [eragrostis tef (zucc.) trotter] is the most preferred ingredient. this study assessed the acceptability of injera prepared using grains of a closely related but underutilized grass, eragrostis curvula (schrad.) nees. the nutritive value of the grains was compared and the sensory attributes of injera made from flours of tef (control) and e. curvula, each com ...201627489554
evaluation of six candidate dna barcode loci for identification of five important invasive grasses in eastern australia.invasive grass weeds reduce farm productivity, threaten biodiversity, and increase weed control costs. identification of invasive grasses from native grasses has generally relied on the morphological examination of grass floral material. dna barcoding may provide an alternative means to identify co-occurring native and invasive grasses, particularly during early growth stages when floral characters are unavailable for analysis. however, there are no universal loci available for grass barcoding. ...201728399170
expressed sequence tag analysis and development of gene associated markers in a near-isogenic plant system of eragrostis curvula.eragrostis curvula (schrad.) nees is a forage grass native to the semiarid regions of southern africa, which reproduces mainly by pseudogamous diplosporous apomixis. a collection of ests was generated from four cdna libraries, three of them obtained from panicles of near-isogenic lines with different ploidy levels and reproductive modes, and one obtained from 12 days-old plant leaves. a total of 12,295 high-quality ests were clustered and assembled, rendering 8,864 unigenes, including 1,490 cont ...200818196464
drought tolerance of selected eragrostis species correlates with leaf tensile properties.previous studies on grass leaf tensile properties (behaviour during mechanical stress) have focused on agricultural applications such as resistance to trampling and palatability; no investigations have directly addressed mechanical properties during water stress, and hence these are the subject of this study.200616621860
influence of protein type and level on nitrogen and forage use in cows consuming low-quality forage.minimal quantities of ruminally degradable protein from supplements may improve supplement use efficiency of ruminants grazing dormant forages. in exp. 1, n retention, ruminal nh(3), serum urea n, and ndf digestibility were evaluated for 12 ruminally cannulated cows (bos spp.) in an incomplete latin square design with 3 periods of 42 d each. cows were fed weeping lovegrass [eragrostis curvula (schrad.) nees] hay (4.1% cp, 75% ndf, om basis) at 1.3 % bw/d and offered 1 of 3 sources of cp [urea, c ...201222287680
translocation of magnaporthe oryzae effectors into rice cells and their subsequent cell-to-cell movement.knowledge remains limited about how fungal pathogens that colonize living plant cells translocate effector proteins inside host cells to regulate cellular processes and neutralize defense responses. to cause the globally important rice blast disease, specialized invasive hyphae (ih) invade successive living rice (oryza sativa) cells while enclosed in host-derived extrainvasive hyphal membrane. using live-cell imaging, we identified a highly localized structure, the biotrophic interfacial complex ...201020435900
a highly divergent south african geminivirus species illuminates the ancient evolutionary history of this family.we have characterised a new highly divergent geminivirus species, eragrostis curvula streak virus (ecsv), found infecting a hardy perennial south african wild grass. ecsv represents a new genus-level geminivirus lineage, and has a mixture of features normally associated with other specific geminivirus genera.200919321000
establishment of three new genera in the family geminiviridae: becurtovirus, eragrovirus and turncurtovirus.the family geminiviridae includes plant-infecting circular single-stranded dna viruses that have geminate particle morphology. members of this family infect both monocotyledonous and dicotyledonous plants and have a nearly global distribution. with the advent of new molecular tools and low-cost sequencing, there has been a significant increase in the discovery of new geminiviruses in various cultivated and non-cultivated plants. in this communication, we highlight the establishment of three new ...201424658781
overexpression and purification of pwl2d, a mutant of the effector protein pwl2 from magnaporthe grisea.the rice blast disease caused by the ascomycete magnaporthe grisea continues to cause a tremendous impact in rice (oryza sativa) cultures around the world. elucidating the molecular basis of the fungus interactions with its host might help increase the general understanding of the pathogen-host relationship. at the moment of invasion, the fungus secretes effectors that modify host defenses and cellular processes as they successively invade living rice cells. pwl2, an effector protein, is a known ...201020438845
putative aspergillus niger-induced oxalate nephrosis in sheep.a sheep farmer provided a maize-based brewer's grain (mieliemaroek) and bales of eragrostis curvula hay to ewes and their lambs, kept on zero-grazing in pens. the 'mieliemaroek' was visibly mouldy. after 14 days in the feedlot, clinical signs, including generalised weakness, ataxia of the hind limbs, tremors and recumbency, were noticed. six ewes died within a period of 7 days. a post mortem examination was performed on 1 ewe. the carcass appeared to be cachectic with mild effusions into the bod ...200919653520
development of plant regeneration and transformation protocols for the desiccation-sensitive weeping lovegrass eragrostis curvula.a tissue culture protocol, suitable for transformation, was established for the pasture grass eragrostis curvula. callus was generated in the dark from leaf and seed tissues on a medium comprising ms salts supplemented with 2 mg/l 2,4-d, 0.01 mg/l bap and 2% sucrose. plant regeneration occurred via organogenesis on the same medium with 6% and 3% sucrose for shoot and root formation, respectively. optimal regeneration (50 plantlets per callus) occurred when light of 45 micromol/m2 per s was used. ...200515776238
embryogenic cell suspensions from different explants and cultivars of eragrostis curvula (schrad.) nees.the aim of this work was the establishment of embryogenic calli and cell suspensions from different explants and cultivars of weeping lovegrass, eragrostis curvula (schrad.) nees, to be used as targets for biolistic transformation. calli were initiated from immature inflorescences, seeds, embryos, leaf bases and root tips. modified ms medium (murashige and skoog, 1962) was used for calli induction and proliferation. cell suspensions were established and maintained in aaf medium (wang et al., 199 ...200111590889
15n estimates of dinitrogen fixation in alfalfa-weeping lovegrass swards under field conditions.information on the amount and proportion of alfalfa (medicago sativa l.) n derived from symbiotic n2 fixation is required in order to exploit this source of n in alfalfa-weeping lovegrass (eragrostis curvula schrad nees) pastures in semiarid argentina. a field experiment was conducted to determine n2 fixation by a legume grown alone or in two different associations with weeping lovegrass, using pure or associated lovegrass as the reference crop. on average, alfalfa derived over 80% of its n from ...19969017853
persistence of the effects of early experience on consumption of low-quality roughage by sheep.the aim of this study was to determine the effects of experience early in life with cured weeping lovegrass (eragrostis curvula) (low-quality roughage) or fresh oats (avena sativa) (high-quality roughage) on voluntary intake and nitrogen retention when sheep ate a low-quality roughage 9 mo after initial exposure. from 1 to 5 mo of age, experienced wethers (ew) grazed cured weeping lovegrass, whereas inexperienced wethers (iw) grazed fresh oats (initial exposure). then both ew and iw were fed sor ...19968726727
amino acid profile and intestinal digestibility in dairy cows of rumen-undegradable protein from various feedstuffs.three lactating cows fitted with rumen cannulas and three cows fitted with proximal duodenal cannulas were used to determine the effect of in situ rumen degradation on the aa profile of rumen-undegraded protein of 12 feedstuffs. intestinal digestibility of rumen-undegraded protein was determined using the mobile bag technique. the absorbable aa profile of rumen-undegraded protein for each feedstuff was compared with profiles of the original feedstuff and the rumen-exposed undegraded protein. bra ...19948182178
effects of early experience on voluntary intake of low-quality roughage by sheep.this study determined 1) how experience early in life with cured weeping lovegrass (eragrostis curvula) (low-quality roughage) or fresh oats (avena sativa) (high-quality roughage) affected consumption of low- or high-quality roughage by lambs later in life and 2) whether this early dietary experience affected passage of undigested residues through the digestive tract and digestion of low-quality roughage. from 1 to 5 mo of age, experienced lambs (el) were grazing cured weeping lovegrass, whereas ...19948056663
identification, cloning, and characterization of pwl2, a gene for host species specificity in the rice blast fungus.genetic analysis of host specificity in the rice blast fungus (magnaporthe grisea) identified a single gene, pwl2 (for pathogenicity toward weeping lovegrass), that exerts a major effect on the ability of this fungus to infect weeping lovegrass (eragrostis curvula). the allele of the pwl2 gene conferring nonpathogenicity was genetically unstable, with the frequent appearance of spontaneous pathogenic mutants. pwl2 was cloned based on its map position. large deletions detected in pathogenic mutan ...19957549480
studies on haemonchus contortus. x. the effect of trichostrongylus axei in merinos on artificial pastures.a recently established eragrostis curvula pasture 1,1 ha in size at hennops river in the transvaal highveld was contaminated from 6 october 1976 until 20 may 1977 by 30 weaned merinos, each infested with 7 000 infective larvae of h. contortus. on 2 november 1976 3 groups of weaned merinos and again on 10 january 1977 a further group of merinos were infested with 40 000 infective larvae of trichostrongylus axei. from 19 november a single group of sheep, predosed with t. axei, and a control group ...19846462632
the non-significant effect of feeding level, growth rate and age on libido of young afrikaner bulls.afrikaner bulls (n = 30) between 9,5 and 15 months old, were allocated to 2 dietary treatments fed ad libitum. diet 1 consisted of 70% concentrate and 30% eragrostis curvula hay (11,4 mj me kg-1 dm) and diet 2 of 40% concentrate and 60% e. curvula hay (9,3 mj me kg-1 dm). five libido tests were conducted per bull between the ages of 16 and 28 months. bulls were pre-stimulated for 10 min by close contact with previously synchronised oestrous heifers. three bulls were then simultaneously allowed a ...19892634771
magnaporthe grisea genes for pathogenicity and virulence identified through a series of backcrosses.we have identified genes for pathogenicity toward rice (oryza sativa) and genes for virulence toward specific rice cultivars in the plant pathogenic fungus magnaporthe grisea. a genetic cross was conducted between the weeping lovegrass (eragrostis curvula) pathogen 4091-5-8, a highly fertile, hermaphroditic laboratory strain, and the rice pathogen o-135, a poorly fertile, female-sterile field isolate that infects weeping lovegrass as well as rice. a six-generation backcrossing scheme was then un ...19912016048
variation in cytosine methylation patterns during ploidy level conversions in eragrostis curvula.in many species polyploidization involves rearrangements of the progenitor genomes, at both genetic and epigenetic levels. we analyzed the cytosine methylation status in a 'tetraploid-diploid-tetraploid' series of eragrostis curvula with a common genetic background by using the msap (methylation-sensitive amplified polymorphism) technique. considerable levels of polymorphisms were detected during ploidy conversions. the total level of methylation observed was lower in the diploid genotype compar ...200919160057
host range and selectivity of the hemiparasitic plant thesium chinense (santalaceae).thesium chinense is a hemiparasitic plant that is common in grassland habitats of eastern asia. although the physiology of thesium has been well studied in attempts to control its weedy habit, there have been few ecological investigations of its parasitic life history. thesium chinense is thought to parasitize species of poaceae, but evidence remains circumstantial.200818492736
gene expression in diplosporous and sexual eragrostis curvula genotypes with differing ploidy levels.the molecular nature of gene expression during the initiation and progress of diplosporous apomixis is still unknown. moreover, the basis of the close correlation between diplospory and polyploidy is not clarified yet. a comparative expression analysis was performed based on expressed sequence tags (ests) sequencing and differential display in an eragrostis curvula diplosporous tetraploid genotype (t, 4x apo), a sexual diploid derivative obtained from tissue culture (d, 2x sex) and an artificial ...200818311543
restoration of drastically eroded land using coal fly ash and poultry biosolid.a 3-year field study was conducted at a 12 ha soil-borrow area adjacent to the columbia metropolitan airport, south carolina to investigate the restorative effects of co-application of coal fly ash (fa) and a poultry biosolid (pb). fa was applied at 0, 22, 280, 560 and 1120 mg (tonne) ha(-1), and pb at 5 and 10 mg ha(-1). the area was seeded with erosion-control species atlantic coastal panic grass (panicum amarum var amarum l.), sericea (lespedeza cuneata var. appalow [dumont] g. don.) and weep ...200212398338
genome polymorphisms and gene differential expression in a 'back-and-forth' ploidy-altered series of weeping lovegrass (eragrostis curvula).molecular markers were used to analyze the genomic structure of an euploid series of eragrostis curvula, obtained after a tetraploid dihaploidization procedure followed by chromosome re-doubling with colchicine. considerable levels of genome polymorphisms were detected between lines. curiously, a significant number of molecular markers showed a revertant behavior following the successive changes of ploidy, suggesting that genome alterations were specific and conferred genetic structures characte ...200716919366
plastic traits of an exotic grass contribute to its abundance but are not always favourable.in herbaceous ecosystems worldwide, biodiversity has been negatively impacted by changed grazing regimes and nutrient enrichment. altered disturbance regimes are thought to favour invasive species that have a high phenotypic plasticity, although most studies measure plasticity under controlled conditions in the greenhouse and then assume plasticity is an advantage in the field. here, we compare trait plasticity between three co-occurring, c(4) perennial grass species, an invader eragrostis curvu ...201222536448
aerospora of an eragrostis curvula pasture in south africa.a qualitative and quantitative survey was made of the aerospora above an eragrostis curvula (schrad.) nees pasture. the pasture, which lay adjacent to a field of panicum coloratum l. where an outbread of ovine photosensitivity had occurred, was not grazed during the survey. a burkard volumetric spore trap was used to sample the aerospora continuously for 10 months. twenty components of the aerospora were recognized: spores of 9 genera of fungi (cladosporium, alternaria, epicoccum, drechslera, pi ...1979460819
dri-grass: a new experimental platform for addressing grassland ecosystem responses to future precipitation scenarios in south-east australia.climate models predict shifts in the amount, frequency and seasonality of rainfall. given close links between grassland productivity and rainfall, such changes are likely to have profound effects on the functioning of grassland ecosystems and modify species interactions. here, we introduce a unique, new experimental platform - dri-grass (drought and root herbivore interactions in a grassland) - that exposes a south-eastern australian grassland to five rainfall regimes [ambient (amb), increased a ...201627703458
comparative digestibility by cattle versus sheep: effect of forage quality.the objective was to determine the effect of forage quality on apparent total tract digestibility and ruminal fermentation in cattle versus sheep. five yearling english crossbred (hereford × angus) steers (440.4 ± 35.6 kg of initial bw) and 5 yearling whiteface (rambouillet × columbia × debouillet) wethers (44.4 ± 4.6 kg of initial bw), each fitted with a ruminal cannula, were randomly assigned to 1 of 3 forage sources within ruminant specie, and the study was conducted over 3 periods. for forag ...201424663196
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