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PubMed2003

Introgression of crown rust (Puccinia coronata) resistance from meadow fescue (Festuca pratensis) into Italian ryegrass (Lolium multiflorum) and physical mapping of the locus.

Resistance was found in the meadow fescue (Festuca pratensis) to crown rust (Puccinia coronata), originating from ryegrasses (Lolium spp). A backcrossing programme successfully transferred this resistance into diploid Italian ryegrass (Lolium multiflorum) and genomic in situ hybridisation (GISH) was used to identify the introgressed fescue chromosome segment. The resistant (R) plants in two BC3 lines all carried an introgressed segment on a single chromosome, which in one of the lines was confined to the short arm of the chromosome. Susceptible (S) plants either contained no introgressed chromosome segment or a segment which was physically smaller than the segments in resistant plants. Using GISH the resistance locus could be physically mapped to the midpoint of a short arm. Segregation ratios of the progeny of BC3 plants, when crossed as R x S and R x R, were in agreement with the hypothesis that the resistance was controlled by a single gene or very closely linked genes. No R plants were produced by crossing S x S plants.

Basidiomycota↗
PubMed1999

A polymorphic duplicated locus for cytosolic PGI segregating in sheep's fescue (Festuca ovina L.)

Normally sheep's fescue (Festuca ovina) carries a single locus encoding the cytosolic enzyme phosphoglucoisomerase (PGI). However, at several localities in southern Sweden plants with more than two different alleles have been found by isozyme studies. Crossing experiments and subsequent progeny analyses revealed two unlinked loci. The additional locus was polymorphic for two alleles with different electrophoretic mobilities. Two of the numerous alleles at the primary locus had the same mobility. A complex gene coding for both electrophoretic types was also found to map to the additional locus, but no such complex gene has been found at the primary locus. The genes at the additional locus can be lacking, or present in hemizygous or homozygous form. Allozymes encoded by the additional locus readily form heterodimers with those encoded by the primary locus, thus giving rise to multibanded isozyme patterns. This segregating, polymorphic gene duplication may well represent a rare case where the initial stage of the evolution of a new gene can be directly studied.

Journal Article↗
PubMed2000

Effects of distance and pollen competition on gene flow in the wind-pollinated grass Festuca pratensis Huds.

Pollen dispersal and gene flow in the grass meadow fescue (Festuca pratensis Huds.) were studied using two populations which were homozygous for different allozymes at the Gpi-2 locus. The populations were established in a concentric donor-acceptor field experiment. Gene flow was found mainly to be affected by the distance between the donor and acceptor plants. Analysing 21 132 acceptor plant progenies, gene flow was shown to decrease rapidly with distance to the donor field up to 75 m, and beyond this distance much more slowly. The ability of donor pollen to fertilize acceptor plants depended very much on the density of the acceptor plants. Pairs of acceptor plants produced more compatible pollen locally, and captured significantly less donor pollen than single-plants. Despite the higher seed production of acceptor plants planted in pairs, the absolute number of heterozygous seeds carrying the donor allele was always lower than for single-plants. Wind direction had only a slight effect upon the type of pollen captured. Because of pollen production within the two plant populations being continuous and overlapping, the time when anthesis occurred had little effect on gene flow between the populations. Vigorous and tall acceptor plants with many panicles, high seed yield and high 1000-seed weight were able to capture more donor pollen than shorter plants. The results may be used to assess the risk of gene flow and to develop strategies for monitoring the spread of transgenes from genetically modified grasses.

Gene Frequency↗
PubMed2003

Improved forage digestibility of tall fescue (Festuca arundinacea) by transgenic down-regulation of cinnamyl alcohol dehydrogenase.

Lignification of cell walls during plant development has been identified as the major factor limiting forage digestibility and concomitantly animal productivity. cDNA sequences encoding a key lignin biosynthetic enzyme, cinnamyl alcohol dehydrogenase (CAD), were cloned from the widely grown monocotyledonous forage species tall fescue (Festuca arundinacea Schreb.). Recombinant tall fescue CAD expressed in E. coli exhibited the highest V(max)/K(m) values when coniferaldehyde and sinapaldehyde were used as substrates. Transgenic tall fescue plants carrying either sense or antisense CAD gene constructs were obtained by microprojectile bombardment of single genotype-derived embryogenic suspension cells. Severely reduced levels of mRNA transcripts and significantly reduced CAD enzymatic activities were found in two transgenic plants carrying sense and antisense CAD transgenes, respectively. These CAD down-regulated transgenic lines had significantly decreased lignin content and altered ratios of syringyl (S) to guaiacyl (G), G to p-hydroxyphenyl (H) and S to H units. No significant changes in cellulose, hemicellulose, neutral sugar composition, p-coumaric acid and ferulic acid levels were observed in the transgenic plants. Increases of in vitro dry matter digestibility of 7.2-9.5% were achieved in the CAD down-regulated lines, thus providing a novel germplasm to be used for the development of grass cultivars with improved forage quality.

Journal Article↗
PubMed1977

Effect of polyploidy on phosphoglucose isomerase diversity in Festuca microstachys.

Studies of the inheritance of electrophoretic banding patterns in Festuca microstachys support the hypothesis that three closely related loci, one located in each of the three ancestral genomes, code the multiple phosphoglucose isomerase (glucosephosphate isomerase; D-glucose-6-phosphate ketol-isomerase, EC 5.3.1.9) variants found in this hexaploid species. The close relationship among the three loci is indicated by the observation that hybrid enzymes of intercistronic origin form when the loci in different genomes carry alleles coding homodimers with unlike migration rates. Homozygous individuals fixed for different alleles in different genomes produce hybrid enzymes and, when self-fertilized, they breed true for isozyme patterns normally found only in the heterozygotes of diploid species. Biochemical diversity due to this "fixed heterozygosity" is high in F. microstachys; although this species is more than 99% self-fertilized the proportion of individuals with at least one heterodimer exceeded 61% in all of the 16 natural populations studied and it exceeded 92% in 11 of the populations. This great biochemical diversity may contribute to the ability of F. microstachys to survive in the wide range of habitats in which it is found over western North America.

Alleles↗
PubMed1975

Separation of Chlorophyll Degradation from Other Senescence Processes in Leaves of a Mutant Genotype of Meadow Fescue (Festuca pratensis L.).

Chlorophyll levels in l-cm sections of the youngest fully expanded leaves of normal (Y) Festuca pratensis L. declined almost to zero over a period of 6 days after excision. Chlorophyll in a mutant genotype (NY) remained near the initial level for the whole of this period. Abscisic acid promoted pigment loss in Y but had no significant effect on chlorophyll in NY. Kinetin retarded pigment loss in Y but was ineffective in NY. Other biochemical changes associated with leaf senescence-reduction in protein content and the appearance of novel isoenzymes of alpha-naphthyl acetate esterases-occurred in both genotypes. Abscisic acid accelerated protein breakdown, whereas kinetin inhibited the loss of protein in both genotypes. The mutation thus appears to be expressed as a highly specific lesion in pigment metabolism. We concluded that pigment breakdown, which is widely used as an index of leaf senescence, may not be an inevitable part of the aging process.

Journal Article↗
PubMed1980

Photosynthesis of Grass Species Differing in Carbon Dioxide Fixation Pathways: V. RESPONSE OF PANICUM MAXIMUM, PANICUM MILIOIDES, AND TALL FESCUE (FESTUCA ARUNDINACEA) TO NITROGEN NUTRITION.

The response of apparent photosynthesis to N nutrition was studied in the C(3) grass, tall fescue (Festuca arundinacea Schreb.), in the C(4) species Panicum maximum Jacq., and in Panicum milioides Nees ex Trin., a species with characteristics intermediate between C(3) and C(4) photosynthetic types. Plants were grown in culture solution containing 1, 5, 50, and 200 milligrams N per liter. Apparent photosynthesis was measured on the youngest fully expanded leaves at 320 microliters of CO(2) per liter of air and 21% O(2). Leaf conductance was calculated from transpiration measurements, and CO(2) compensation concentrations were also estimated. Several leaf anatomical characteristics were studied on plastic-embedded material. Leaf N content was determined on leaves which were used in photosynthesis measurements.Apparent photosynthesis increased in a linear fashion with increases in leaf N content in all three species. The increase in apparent photosynthesis per unit increase in leaf N was over twice as great in P. maximum (9.7 milligrams CO(2) per square decimeter per hour for each increase of 1% leaf N) as in P. milioides and tall fescue. Apparent photosynthesis and its response to N level were similar in P. milioides and tall fescue, but at leaf N concentrations above 2%, apparent photosynthesis in these two species was only about one-half of that in P. maximum. Increases in apparent photosynthesis due to higher N levels were accompanied by increases in both leaf and mesophyll conductances in P. maximum, whereas in P. milioides and tall fescue only mesophyll conductance was significantly correlated with leaf N. Water use efficiency (apparent photosynthesis/transpiration) increased in a linear manner with increased leaf N in all three species but was more closely related to leaf N in P. milioides and tall fescue than in P. maximum. High N levels tended to increase leaf thickness and interveinal distance in all three species. The percentage of air space in leaf tissue and the mesophyll cell diameter were either not affected or changed only slightly by N nutrition with the exception that percentage of air space in tall fescue leaves rose from 17.3 to 24.8 with an increase in solution N level from 1 to 200 milligrams per liter. Although P. milioides has been shown to have photosynthetic and leaf anatomical characteristics intermediate to C(3) and C(4) species, its response to N was similar to that of the C(3) grass, tall fescue.

Journal Article↗
PubMed1988

Fructan Content and Synthesis in Leaf Tissues of Festuca arundinacea.

The concentration of fructan in tall fescue (Festuca arundinacea Schreb.) changes during growth and in response to environment. The objective of this research was to compare the fructan concentration and fructosyl-transferase activity of tall fescue leaf tissues. Expanding leaves, inner and outer sheaths, and expanded blades of greenhouse-grown tall fescue plants were assayed for fructan concentration and fructosyl-transferase activity. Leaf sheaths contained significantly more nonstructural carbohydrate than did the expanded blade. Sheaths also contained a greater percentage of fructan with more than six sugar residues (long chain fructan), than either the expanded blade or expanding leaf. Expanding leaves contained a greater concentration of fructose and oligosaccharides than did sheath or blade tissues. Expanding leaves also had the greatest fructosyl-transferase activity measured either as radiolabel incorporated into fructans in tissue pieces or protein extracts. Activity of fructosyl-transferase was greater in expanding leaf tissue than in sheath tissues.

Journal Article↗
PubMed1990

Detection of Kestoses and Kestose-Related Oligosaccharides in Extracts of Festuca arundinacea, Dactylis glomerata L., and Asparagus officinalis L. Root Cultures and Invertase by C and H Nuclear Magnetic Resonance Spectroscopy.

A previous study (KL Forsythe, MS Feather [1989] Carbohydr Res 185: 315-319) showed that (13)C nuclear magnetic resonance spectroscopy can be used to detect and identify mixtures of 1-kestose and neokestose after conversion to the acetate derivatives. In this study, unequivocal assignments are made for the anomeric carbon and proton signals for the above two trisaccharide acetates as well as for 6-kestose hendecaacetate and for nystose tetradecaacetate (a 1-kestose-derived tetrasaccharide). A number of oligosaccharide fractions were isolated from several plant species, converted to the acetates, and nuclear magnetic resonance spectra obtained. Using the above reference data, the following information was obtained. The trisaccharide fraction from Dactylis glomerata L. stem tissue and Asparagus officinalis L. roots contain both 1-kestose and neokestose, and the tetrasaccharide fractions contain three components, one of which is nystose. Penta- and hexasaccharide acetates were also isolated from A. officinalis L. roots and were found to contain, respectively, four and at least five components. All components of both of the above species appear to contain a kestose residue and to be produced by the sequential addition of fructofuranosyl units to these. The trisaccharide fraction from Festuca arundinacea is complex, and contains at least five different components, two of which appear to be 1-kestose and neokestose.

Journal Article↗
PubMed1990

Leaf Senescence in a Nonyellowing Mutant of Festuca pratensis: Metabolism of Cytochrome f.

In a mutant genotype of Festuca pratensis Huds., net degradation of a number of thylakoid membrane proteins during senescence is impaired. Previous studies have suggested that the highly hydrophobic intrinsic chlorophyll-binding proteins were the definitive subjects of the metabolic lesion. In the present study we find that cytochrome f, as determined by haem-staining, Western blotting, enzyme-linked immunosorbent assay, and immunogold electron microscopy, is also abnormally stable in the mutant. The structural feature common to all the proteins in the mutant so far recognized to be abnormally stable is possession of a tetrapyrrole prosthetic group. It is suggested that degradation of chlorophyll and haem may regulate degradation of the associated apoproteins, and hence has an important role to play in membrane protein turnover and in mobilisation of amino acids during chloroplast disassembly.

Journal Article↗
PubMed1996

An attempt to reproduce 'mal seco' in horses by feeding them Festuca argentina.

'Mal seco' is an almost invariably fatal disease of horses in Argentina and Chile, which resembles grass sickness, a dysautonomia of horses in Europe. The aetiology of mal seco remains unknown. An attempt to reproduce the disease was made by feeding horses with Festuca argentina, a plant considered to be toxic to animals and which was consistently found in the diet of nine horses suffering from mal seco. Three horses were fed with F argentina ad libitum for 28 days. The plant was infected with an endophytic fungus, whose morphological characteristics were in agreement with descriptions of Acremonium chlamydosporioides. No clinical abnormalities were observed in two of the horses, but one died on the fifth day of the trial after becoming incoordinated, unsteady and ataxic in the fore- and hindlimbs. No gross changes were observed post mortem in any of the horses, with the exception of a small number of Fasciola hepatica in the liver of the horse which died, and a moderate number of Gasterophilus species in the stomach of all three horses. No histopathological changes were observed in any of the organs examined, including several autonomic ganglia, brain including most brain stem nuclei, spinal cord, liver, kidney, stomach and small and large intestine. The results of this study suggest that F argentina is either not implicated in the aetiology of mal seco or produces its effects only when they are triggered by other unknown factors.

Acremonium↗
PubMed1984

Comparison of Festuca leaf streak virus antigens with those of three other rhabdoviruses infecting the Gramineae.

Leaf tissue from plants infected with Festuca leaf streak virus was extracted with a buffer containing a nonionic detergent; this treatment released the G protein from the nucleocapsid of virions. The extract was tested with antiserum by double immunodiffusion for G protein and by immunosorbent electron microscopy with 'decoration' for nucleocapsid antigens. Clear homologous reactions were obtained. No heterologous reactions were observed with similar preparations of barley yellow striate mosaic, northern cereal mosaic, and cereal chlorotic mottle viruses.

Antigens, Viral↗
PubMed2001

A simple thin-layer chromatographic method for the detection of ergovaline in leaf sheaths of tall fescue (Festuca arundinacea) infected with Neotyphodium coenophialum.

A relatively simple and inexpensive thin-layer chromatographic (TLC) method is described for the detection and semiquantitative measurement of ergovaline in leaf sheaths of tall fescue (Festuca arundinacea). Samples were finely ground and extracted with methanol. The extracts were filtered and the methanol was evaporated. The aqueous residue was extracted with hexane, followed by chloroform at pH 9. The chloroform extract was concentrated and further purified on a preparative silica gel TLC plate, developed with toluene/ethyl acetate/acetonitrile (50:10:40). The ergovaline band was scraped and eluted with methanol. The eluant was concentrated and an aliquot was applied to a silica gel TLC plate. The plate was developed successively with chloroform/acetone/acetic acid (90:10:5) and chloroform/ethanol (9:1). Ergovaline was visualized with p-dimethylaminobenzaldehyde and sulfuric acid. Semiquantitation of ergovaline was achieved by comparison with a known standard of ergotamine, which was shown to have the same Rf as ergovaline in this system. Spike recovery of ergotamine averaged 60%, with a limit of detection of 200 microg/kg of dry tall fescue leaf sheaths. The method was applied to 15 tall fescue samples with varying degrees of fungal infection, and ergovaline was identified in all contaminated samples with endophyte infection above 15%. Thin-layer chromatography may be also applicable for tall fescue seed, where the ergovaline content is usually higher and the amount of interfering pigments is much lower.

Acremonium↗
PubMed1981

The intranuclear relationship between centromere volume and chromosome size in Festuca scariosa X drymeja.

In the hybrid Festuca scarisoa X drymeja where pairing is incomplete at pachytene, there is preferential pairing between the longer chromosomes of the complement. EM serial-section reconstruction of nuclei at zygotene and pachytene reveals that there is equally pronounced preferential pairing between larger centromeres. This evidence suggests that the longer chromosomes have large centromeres and that centromere volume is correlated with chromosome length. Confirmation of this comes from the comparison of the frequency distributions of observed centromere volumes and those predicted on the basis of chromosome length. Although there is a positive correlation between centromere volume and chromosome length, it is not possible to identify the centromeres of each individual chromosome within the complement because (a) the differences between the lengths of each chromosome are small and (b) the estimates of relative centromere volumes vary significantly between cells.

Cell Nucleus↗
PubMed2004

Gangrenous ergotism in cattle grazing fescue (Festuca elatior L.) in South Africa.

The 1st outbreak of fescue toxicosis in South Africa was recently confirmed in a Brahman herd at Perdekop, near Standerton, in Mpumalanga province, South Africa. Within 3 weeks of being placed on a fescue pasture in mid-winter, 50 of 385 cattle developed lameness and/or necrosis of the tail. The farmer had established Festuca elatior L. (tall fescue, Iewag variety) on c. 140 ha for winter grazing. Fescue may be infected by an endophyte, Neotyphodium coenophialum, which produces ergot alkaloids, in particular ergovaline. Ergovaline concentrations in basal leaf sheaths and grass stems collected during the outbreak ranged from 1720-8170 ppb on a dry-matter basis.

Animals↗
PubMed2000

Effect of nitrogen supply and defoliation on loss of organic compounds from roots of Festuca rubra.

The aim of this study was to determine the effects of N-supply and defoliation on rhizodeposition from Festuca rubra, in the context of whole-plant C- partitioning and root morphology. Plants were grown for 36 d in axenic sand microcosms continuously percolated with nutrient solutions of either high or low N concentration (2 mM or 0.01 mM NH(4)NO(3), respectively). The effects of partial defoliation at weekly intervals were determined at high and low N. At low N, dry matter accumulation in roots and shoots was reduced significantly (P<0.001), with proportionately increased partitioning to roots, in comparison with the high N treatment. Root morphology was also affected by N-treatment; at low N, lower biomass production was offset by increased specific root length (P<0.001), reducing the magnitude of the significant (P=0.002) increase in total root length at high N. Cumulative release of organic C from roots of F: rubra over the experimental period was not altered significantly by N-treatment. However, as a proportion of net C-assimilation, rhizodeposition was significantly (P<0.001) greater at low N than at high N. Defoliation transiently (3-5 d) increased the release of soluble organic compounds from roots at each N-supply rate, and increased significantly (P<0.001) cumulative rhizodeposition over the experimental period. These effects of N-supply and defoliation on rhizodeposition are of importance in understanding interactions between plant and microbial productivity in grazed grasslands, and in interpretation of concurrent effects on microbially driven nutrient cycling processes in these systems.

Nitrogen↗
PubMed1985

[Survival of Azospirillum in the rhizosphere of Festuca arundinacea].

In two experiments Festuca seeds (4 or 20 seeds/pot in first or second experiment respectively) were inoculated with Azospirillum strains (sp 7, mutant streptomycin resistant and G strain) in controlled laboratory conditions. Two illumination regimes were employed (197 and 274 microE. m-2.s-1, respectively). sp 7 cell number was determined during both experiments. The total number of diazotrophic bacteria was also determined on different dates. In both experiments the control pots received the same number of autoclaving bacteria. The results suggested that: (i) sp 7 number decreased in both experiments to 4 - 5% from initial number in 22 and 23 day after inoculation. This suggests that the plant density and illumination range employed did not affect the inoculum survival; (ii) the evolution of the number of different native diazotrophics strains, along the experiment, showed that this microbial number decrease in inoculated and control pots was related to the initial number.

Poaceae↗