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Use of random PCR (RAPD) technology to analyse phylogenetic relationships in the Lolium/Festuca complex.

The RAPD PCR technique has been employed to investigate phylogenetic relationships between species of the genera Lolium and Festuca. Several decamer primers were used to generate patterns from groups of genotypes of several different species. The degree of band sharing was used to evaluate genetic distances between species and to construct a phylogenetic tree which is in good overall agreement with classical taxonomy, but contains a number of novel insights. The degree of homoplasy inherent in this approach has been investigated using Southern hybridization. These results are discussed in the context of current work in molecular biosystematics.

Base Sequence↗

Evolutionary dynamics and chromosomal distribution of repetitive sequences on chromosomes of Aegilops speltoides revealed by genomic in situ hybridization.

Simultaneous genomic in situ hybridization (GISH) with probe preannealing was used to detect the relationship between chromosomal position and sequence conservation on Aegilops speltoides var. aucheri chromosomes. DNA of Secale sylvestre, Hordeum spontaneum, Festuca pratensis, Semiarundinaria fastuosa, Arundo donax and Zea mays that represent several main groups of Poaceae were used as probes. Different GISH-banding patterns that characterize diverse evolutionary trajectories in the repetitive DNA fraction and correlate with evolutionary distance between tested species were observed. Fast-evolving sequences were detected in subterminal telomeric and subtelomeric heterochromatic regions, whereas sequences in pericentromeric regions showed high levels of conservation. GISH experiments revealed extensive conservation in NOR regions on chromosomes 1 and 6 which, in fact, appears to be a complicated mix of rDNA clusters and heterochromatin blocks of different nucleotide composition.

Chromosome Banding↗

Graminicide insensitivity correlates with herbicide-binding co-operativity on acetyl-CoA carboxylase isoforms.

The sensitivity of grass species to important classes of graminicide herbicides inhibiting ACCase (acetyl-CoA carboxylase) is associated with a specific inhibition of the multifunctional ACCase located in the plastids of grasses. In contrast, the multisubunit form of ACCase found in the chloroplasts of dicotyledonous plants is insensitive and the minor cytosolic multifunctional isoforms of the enzyme in both types of plants are also less sensitive to inhibition. We have isolated, separated and characterized the multifunctional ACCase isoforms found in exceptional examples of grasses that are either inherently insensitive to these graminicides, or from biotypes showing acquired resistance to their use. Major and minor multifunctional enzymes were isolated from cell suspension cultures of Festuca rubra and the 'Notts A1'-resistant biotype of Alopecurus myosuroides, and their properties compared with those isolated from cells of wild-type sensitive A. myosuroides or from sensitive maize. Purifications of up to 300-fold were necessary to separate the two isoforms. The molecular masses (200-230 kDa) and K(m) values for all three substrates (ATP, bicarbonate and acetyl-CoA) were similar for the different ACCases, irrespective of their graminicide sensitivity. Moreover, we found no correlation between the ability of isoforms to carboxylate propionyl-CoA and their sensitivity to graminicides. However, insensitive purified forms of ACCase were characterized by herbicide-binding co-operativity, whereas, in contrast, sensitive forms of the enzymes were not. Our studies on isolated individual isoforms of ACCase from grasses support and extend previous indications that herbicide binding co-operativity is the only kinetic property that differentiates naturally or selected insensitive enzymes from the typical sensitive forms usually found in grasses.

Acetyl-CoA Carboxylase↗

Endotransglycosylation of xyloglucans in plant cell suspension cultures.

1. A xyloglucan-derived nonasaccharide ([3H]XG9; Glc4,Xyl3,Gal,Fuc) was neither taken up by cultured plant cells nor appreciably hydrolysed by them, but a proportion of it became incorporated into extracellular polymers in all cultures tested (Spinacia, Daucus, Rosa, Acer, Capsicum, Zea and Festuca). 2. In Spinacia these polymers were soluble in 20% (w/v) trichloroacetic acid, had apparent Mr 20,000-30,000, were able to bind reversibly to cellulose powder and were susceptible to hydrolysis by endo-beta-(1----4)-D-glucanase, indicating that they were xyloglucans. 3. The linkage formed between [3H]XG9 and the xyloglucan was alkali-stable and glucanase-labile, indicating that the reaction responsible for the incorporation was a transglycosylation. 4. The reducing terminus of the XG9 moiety remained reducing (convertible into [3H]glucitol by NaBH4) after incorporation into the polymer, showing that the XG9 was the glycosyl acceptor and the polysaccharide the donor. 5. The results provide the first evidence that polymeric xyloglucans are subject in vivo to cleavage followed by transfer of the cut end on the other xyloglucan-related molecules. 6. Similar endotransglycosylation reactions could occur within the primary cell wall, between pairs of high-Mr structural xyloglucan molecules. Such a reaction would provide a mechanism for reversible wall loosening and may thus be relevant to our understanding of plant cell growth.

Carbohydrate Conformation↗

Detection and quantification of group 4 allergens in grass pollen extracts using monoclonal antibodies.

BACKGROUND: Grass pollen extracts are complex mixtures consisting of different major allergenic and non-allergenic components. Phl p 4 is an important allergen, because more than 75% of grass pollen allergic patients produce specific IgE antibodies against group 4 allergens. OBJECTIVE: This study was designed to investigate the specificity of monoclonal antibodies (MoAbs) produced against Phl p 4 and to verify the presence of group 4-like proteins in different grass pollen. Furthermore the usefulness of MoAbs for quantification of group 4 allergens was studied. METHODS: Group 4 analogues were investigated by immunoblotting and ELISA inhibition using three MoAbs. The specificity of antibodies was studied using isolated group 1 and group 5 allergens. Quantification of group 4 allergen was achieved by a two-site solid-phase ELISA. Phl p 4 was purified from whole pollen extract by chromatographic or electrophoretic techniques and used as standard. RESULTS: The MoAbs studied bound strongly to proteins from timothy grass pollen extract at a mw of 55 kDa and a pI of 9.0-9.3. Phl p 4 homologes with similar mw were detected in Dactylis glomerata, Festuca pratensis, Holcus lanatus, Poa pratensis, Lolium perenne. Epitope mapping showed that all three MoAb recognized unrelated regions on Phl p 4. A two-site binding ELISA using MoAbs was developed for determination of Phl p 4 in Phleum pratense extracts. The method was able to evaluate group 4 in mass units with a working range between 150 and 2000 ng/mL. The absolute amounts of group 4 in extracts of several grasses varied considerably but was always-less than 1% of the total protein. CONCLUSION: Group 4 homologes are present in the various grass extracts but to different extents. The group 4 ELISA could be very useful as a additional tool for providing information concerning the composition of grass pollen extracts.

Allergens↗

Subtribe-specific monoclonal antibodies to Lolium perenne.

BACKGROUND AND OBJECTIVES: The ability to measure personal exposure to airborne grass pollen is important in the understanding of allergic diseases. Visual identification is time consuming and it is difficult to distinguish between many grass pollens morphologically. Although grass pollens share common allergenic determinants, we attempted to produce monoclonal antibodies that would distinguish between species, tribes and subfamilies of grasses which would allow immunodetection of pollens. METHODS: Monoclonal antibodies raised against Lolium perenne were screened for specificity against an extended panel of grass pollen extracts using standard ELISA techniques and a novel particle blotting assay using whole pollen grains. RESULTS: Antibodies showing specificity ranging from subfamily to part-tribe specificity were raised. The most specific monoclonal antibodies (numbers 4, 13 and 17) had reactivity to Lolium perenne and Festuca elatior but displayed little cross-reactivity to Phalaris arundinaceae and the rest of the Poeae tribe when tested by ELISA and no detectable cross-reaction when tested with particle blotting. CONCLUSION: Monoclonal antibodies that are functionally specific to only two grasses can be produced and used to discriminate between related grass species.

Allergens↗

Molecular barcodes for soil nematode identification.

Using a molecular barcode, derived from single-specimen polymerase chain reaction (PCR) and sequencing of the 5' segment of the small subunit ribosomal RNA (SSU) gene, we have developed a molecular operational taxonomic unit (MOTU) scheme for soil nematodes. Individual specimens were considered to belong to the same MOTU when the sequenced segment of 450 bases was > 99.5% identical. A Scottish upland Agrostis-Festuca grassland soil was sampled, using both culture-based and random selection methods. One hundred and sixty-six cultured isolates were sequenced, and clustered into five MOTU. From 74 randomly sampled individuals across the study site, 19 MOTU were defined. A subsequent sample of 18 individuals from a single subplot contained eight MOTU, four of which were unique to the single subplot sample. Interestingly, seven of these MOTU were not present in the culture-independent sampling. Overall, a total of 23 MOTU were defined from only 240 sequences. Many MOTU could readily be assigned to classical, morphologically defined taxonomic units using a database of SSU sequences from named nematode species. The MOTU technique allows a rapid assessment of nematode taxon diversity in soils. Correlation with a database of sequences from known species offers a route to application of the technique in ecological surveys addressing biological as well as genetic diversity.

Animals↗

Co-existing grass species have distinctive arbuscular mycorrhizal communities.

Arbuscular mycorrhizal (AM) fungi are biotrophic symbionts colonizing the majority of land plants, and are of major importance in plant nutrient supply. Their diversity is suggested to be an important determinant of plant community structure, but the influence of host-plant and environmental factors on AM fungal community in plant roots is poorly documented. Using the terminal restriction fragment length polymorphism (T-RFLP) strategy, the diversity of AM fungi was assessed in 89 roots of three grass species (Agrostis capillaris, Festuca rubra, Poa pratensis) that co-occurred in the same plots of a field experiment. The impact of different soil amendments (nitrogen, lime, nitrogen and lime) and insecticide application on AM fungal community was also studied. The level of diversity found in AM fungal communities using the T-RFLP strategy was consistent with previous studies based on clone libraries. Our results clearly confirm that an AM fungal host-plant preference exists, even between different grass species. AM communities colonizing A. capillaris were statistically different from the others (P < 0.05). Although grass species evenness changed in amended soils, AM fungal community composition in roots of a given grass species remained stable. Conversely, in plots where insecticide was applied, we found higher AM fungal diversity and, in F. rubra roots, a statistically different AM fungal community.

Analysis of Variance↗

Evolutionary diversification of fungal endophytes of tall fescue grass by hybridization with Epichloë species.

The mutualistic associations of tall fescue (Festuca arundinacea) with seed-borne fungal symbionts (endophytes) are important for fitness of the grass host and its survival under biotic and abiotic stress. The tall fescue endophytes are asexual relatives of biological species (mating populations) of genus Epichloë (Clavicipitaceae), sexual fungi that cause grass choke disease. Isozyme studies have suggested considerable genetic diversity among endophytes of tall fescue. Phylogenetic relationships among seven isolates from tall fescue, three from meadow fescue (a probable ancestor of tall fescue), and nine Epichloë isolates from other host species were investigated by comparing sequences of noncoding segments of the beta-tubulin (tub2) and rRNA (rrn) genes. Whereas each Epichloë isolate and meadow fescue endophyte had only a single tub2 gene, most tall fescue endophytes had two or three distinct tub2 copies. Phylogenetic analysis of tub2 sequences indicated that the presence of multiple copies in the tall fescue endophytes was a consequence of hybridization with Epichloë species. At least three hybridization events account for the distribution and relationships of tub2 genes. These results suggest that interspecific hybridization is the major cause of genetic diversification of the tall fescue endophytes.

Amino Acid Sequence↗

Molecular cloning and characterization of cDNAs encoding cinnamoyl CoA reductase (CCR) from barley (Hordeum vulgare) and potato (Solanum tuberosum).

Cinnamoyl CoA reductase catalyzes the reduction of cinnamic acid CoA esters into their corresponding aldehydes, the first step of the phenylpropanoid pathway specifically dedicated to monolignol biosynthesis. Two cDNA clones encoding cinnamoyl CoA reductase (CCR) have been isolated from Hordeum vulgare (HvCCR) and Solanum tuberosum (StCCR1). Amino acid sequence alignment revealed the motif, NWYCY, representing the active site of CCR, conserved in both the encoded HvCCR and StCCR1 amino acid sequences. The HvCCR encoded protein possesses substantial homology with CCRs isolated and cloned form other sources; the highest identity (89%) was observed with CCR from fescue (Festuca arundicinea). Expression analysis by RT-PCR demonstrated that the HvCCR gene is expressed in barley stem and root tissue while no expression is detected in leaves and flowers. This expression pattern suggests that HvCCR is involved in constitutive lignification. Transcripts of StCCR1 were detected in potato root, leaf and also in stem although at a very low level.

Aldehyde Oxidoreductases↗

Threonine metabolism in sheep. I. Threonine catabolism and gluconeogenesis in mature Blackface wethers given poor quality hill herbage.

In three experiments, mature Blackface wethers were given freeze-stored Agrostis festuca herbage by continuous feeder. In Expt 1, on separate occasions [U-14C]threonine, [U-14C]glucose and NaH14CO3 were infused over 12 h periods to obtain estimates of irreversible loss rate (ILR) of threonine, glucose and carbon dioxide in the plasma and of the exchange of C between these metabolites. In Expts 2 and 3, during periods when glucose and threonine metabolism were examined, glucose loss across the kidneys (23-29 g/d) was induced by infusion of phloridzin. Results from the four sheep used in Expts 1 and 3 are presented as three-pool models. They indicate that threonine ILR (7.8 g/d; 3.1 g C/d) was approximately three times the estimated rate of absorption of exogenous threonine (1 g C/d). Glucose ILR was approximately 76 g/d (mean +/- SE; 30.3 +/- 0.57 g C/d). Only 0.3% of the glucose-C (0.09 g/d) was derived directly from threonine-C (i.e. 3% of the threonine-C ILR). Bicarbonate ILR was 170 +/- 7.3 g C/d, and glucose contributed 11.1 +/- 3.52 g C/d to this, accounting for 51 +/- 4.4% of glucose-C ILR. Threonine contributed 0.20 +/- 0.026 g C/d to the bicarbonate-C ILR, accounting for only 6.4 +/- 0.87% of the threonine-C ILR. When, in Expts 2 and 3, phloridzin was infused, glucose ILR was increased by 28 +/- 1.5% and bicarbonate ILR was increased by 13 +/- 2.4%. Threonine ILR (3.1 g C/d) was not increased, but the metabolic distribution of threonine-C was altered. The transfer of threonine-C into glucose and CO2 was increased by 39 and 69% respectively to 0.125 and 0.45 g C/d, accounting for 4 and 13% of the threonine ILR respectively. Both technical and metabolic considerations which affect interpretation of these results in terms of rates of catabolism of threonine and of quantitative estimates of gluconeogenesis from threonine are discussed.

Animal Feed↗

Effects of ruminant digestion and metabolism on phenolic monomers of forages.

Immature and mature lucerne (Medicago sativa) and tall fescue (Festuca arundinacea) hays were analysed for their lignin and phenolic monomer (hydroxybenzoic and hydroxycinnamic acid derivatives) contents. These hays were given to four sheep with rumen, duodenal and ileal cannulas, and to a steer with rumen and abomasal cannulas, to investigate the extent and sites of digestion of lignin and phenolic monomers. The hays and digesta samples were analysed for alkali and nitrobenzene-extractable phenolic monomers. Lanthanum oxide was used as an external marker in the digestion studies. Urine was also collected for estimates of total phenolic balance. Grass hays contained greater concentrations of alkali-labile phenolic monomers than did legume hays, whereas legume hays had higher levels of nitrobenzene oxidation products. Mature tall fescue hay had greater concentrations of phenolic monomers than did immature tall fescue hay, but corresponding differences with maturity were not observed with lucerne hays. There were quantitative differences between diets in the digestibilities and in the sites of digestion of phenolic monomers. Digestibilities ranged from 0.191 to 1.004 for alkali-labile compounds and from -1.137 to 0.868 for nitrobenzene oxidation products. Composition of lignin was altered during its passage through the digestive tract. The proportion of phenolic monomers not recovered in urine and faeces varied from -1.014 to 0.871 for individual compounds and differed between diets. Soluble phenolic monomers decreased in concentration as digesta passed from the rumen to the abomasum and duodenum, but increased again in the ileum; levels varied with diet. Phenolics were rapidly solubilized in the rumen after feeding. Results indicate that forages differ in their phenolic monomer content and in the digestibility of these compounds. Therefore, lignin is not an inert compound in the digestive tract of ruminants as has been previously reported.

Animals↗

Enzyme supplementation, degradation and metabolism of three U-14C-labelled cell-wall substrates in the fowl.

An experimental model is described that was used for assessing in vivo effects in fowls of exogenous enzyme supplementation on the degradation of plant cell walls to metabolizable monosaccharide residues. It was based on tube-feeding U-14C-labelled cell-wall substrates, cellulose, spinach (Spinacia oleracea) or Festuca, with and without enzyme treatments, and monitoring recovery of 14C radioactivity in exhaled carbon dioxide and excreta in the following 8 h. Normal digestion of cell-wall polysaccharides by endogenous microbial activity was also studied by pretreating birds with an antibiotic mixture intended to deplete their intestinal microflora. The results of this pretreatment appeared to confirm the existence of microbial degradation of cellulose in (conditioned) fowls. Judging from differences in 14CO2 production, effects of exogenous enzyme additions were greatly enhanced with all substrates by combining them with a wet pretreatment, thereby increasing the time-period available for them to act in aqueous conditions. However, estimations of digestibilities of cellulose, hemicellulose and pectin with dry and wet treatments, based on recovery of 14C in excreta, indicated that it was only cellulose digestion that was improved by the wet pretreatment. This suggests that degradation of cellulose, which appeared to be slowest, was limited by the dry treatments, whereas that of hemicellulose and pectin was not. Respective digestibilities of these three cell-wall components, from all treatments combined, were in the proportions 1:1.5:4.2.

Animals↗

Towards sustainable production of protein-rich foods: appraisal of eight crops for Western Europe. PART II: Analysis of the technological aspects of the production chain.

Increased production of plant protein is required to support the production of protein-rich foods which can replace meat in the human diet to reduce the strain that intensive animal husbandry poses on the environment. The suitability of lupin (Lupinus spp.), pea (Pisum sativum), quinoa (Chenopodium quinoa Willd.), triticale (x Triticosecale), lucerne (Medicago sativa), grasses (Lolium and Festuca spp.), rapeseed/canola (Brassica napus) and potato (Solanum tuberosum) for protein production in Western Europe was studied on the basis of a chain-approach. The technological aspects, which are considered in this paper, are the processing methods, and the functional and nutritional properties of the derived protein products. The overall evaluation of the technological prospects of the eight crops as a protein source for Western Europe leads to the conclusion that this part of the production chain is not decisive for that choice. Pea and lupin have a slight advantage over the other crops, because their concentrates and isolates are already commercially available.

Agriculture↗

Potential for phytoremediation of polychlorinated biphenyl-(PCB-)contaminated soil.

Weathered soils contaminated with commercial-grade Aroclor 1260 from three sites in Canada were used to investigate the polychlorinated biphenyl (PCB) phytoextraction potential of nine plant species (Festuca arundinacea, Glycine max, Medicago sativa, Phalaris arundinacea, Lolium multiflorum, Carex normalis, and three varieties of Cucurbita pepo ssp. pepo) under controlled greenhouse conditions. The soils used varied in PCB concentration (90-4200 microg/g) and total organic content (0.06-2.02%). Greenhouse experiments controlled for PCB volatilization through the use of a vented enclosure and by isolating the contaminated soils with parafilm. After 8 wks, PCB concentrations of 47-6700 microg/g were observed in root tissues. Although PCB concentrations in shoot tissues were lower (< 1-470 microg/g), the absolute amounts of PCBs observed in shoot tissue were significant (1.7-290 microg) once shoot biomass was accounted for. Congener signatures indicated that tetra- to hexa-chlorobiphenyls contributed the largest proportions to shoot tissues, but hepta-to nona-chorobiphenyls were also present in measurable amounts. Overall, the results indicate that varieties of C. pepo were more effective at extracting PCBs from soil than other plants screened The evidence suggests that this was mainly due to root uptake of PCBs and tranlocation to the shoots, rather than volatilization of PCBs from soil. All plants screened showed signs of stress in the most highly contaminated soil (4200 microg/g), but not in the two lower PCB contaminated soils (250 and 90 microg/g, respectively). No detectable decreases in soil PCB concentrations were observed in these short-term greenhouse experiments, but the results suggest that this may be achievable through multiple plantings.

Biodegradation, Environmental↗

Effectiveness of phytoremediation as a secondary treatment for polycyclic aromatic hydrocarbons (PAHs) in composted soil.

A greenhouse study was conducted over a 12-month period to investigate the fate of polycyclic aromatic hydrocarbons (PAHs) in soil using phytoremediation as a secondary treatment. The soil was pretreated by composting for 12 weeks, then planted with tall fescue (Festuca arundinacea), annual ryegrass (Lolium multiflorum), and yellow sweet clover (Melilotus officinalis). Two sets of unvegetated controls also were evaluated, one fertilized and one unfertilized. Total PAH concentrations decreased in the tall fescue, annual ryegrass, and yellow sweet clover treatments by 23.9%, 15.3%, and 9.1%, respectively, whereas the control was reduced by less than 5%. The smaller two- and most of the three-ringed compounds--naphthalene, acenaphthylene, acenaphthene, fluorene, and anthracene--were not found in detectable concentrations in any of the treatments. The most probable number analysis for microbial PAH degraders did not show any statistically significant differences among treatments. There were significant differences among treatments (p < 0.05) for the residual concentrations of five of the target PAHs. Root surface area measurements indicated that tall fescue and annual ryegrass both had significantly higher root surface area than yellow sweet clover, although the two species were not significantly different from each other. The tall fescue treatment resulted in the highest root and shoot biomass, followed by annual ryegrass and yellow sweet clover, and also had the highest percent of contaminant removal after 12 months. These results imply a positive relationship between plant biomass development and PAH biodegradation.

Biodegradation, Environmental↗

Toward sustainable production of protein-rich foods: appraisal of eight crops for Western Europe. Part I. Analysis of the primary links of the production chain.

Increased production of plant protein is required to support the production of protein-rich foods that can replace meat in the human diet to reduce the strain that intensive animal husbandry poses to the environment. The suitability of lupin (Lupinus spp.), pea (Pisum sativum), quinoa (Chenopodium quinoa Willd.), triticale (x Triticosecale), lucerne (Medicago sativa), grasses (Lolium and Festuca spp.), rapeseed/canola (Brassica napus), and potato (Solanum tuberosum) for protein production in Western Europe was studied on the basis of a chain approach. The aspects considered are the familiarity of farmers with the cultivation of the crop, prospects for rapid crop improvement, protein production (kg/ha), protein quality (absence of unwanted substances) and familiarity with the usage for human food in Western Europe. Pea, lucerne, and grasses are the most promising, fair prospects are foreseen for lupin, triticale, rapeseed, and potato, whereas the possibilities for quinoa are judged to lag far behind. Estimated protein production for pea, lucerne, and grasses is 1250, 2500, and 2500 kg/ha, respectively.

Agriculture↗

Secondary cell wall deposition causes radial growth of fibre cells in the maturation zone of elongating tall fescue leaf blades.

A gradient of development consisting of successive zones of cell division, cell elongation and cell maturation occurs along the longitudinal axis of elongating leaf blades of tall fescue (Festuca arundinacea Schreb.), a C3 grass. An increase in specific leaf weight (SLW; dry weight per unit leaf area) in the maturation region has been hypothesized to result from deposition of secondary cell walls in structural tissues. Our objective was to measure the transverse cell wall area (CWA) associated with the increase in SLW, which occurs following the cessation of leaf blade elongation at about 25 mm distal to the ligule. Digital image analysis of transverse sections at 5, 15, 45, 75 and 105 mm distal to the ligule was used to determine cell number, cell area and protoplast area of structural tissues, namely fibre bundles, mestome sheaths and xylem vessel elements, along the developmental gradient. Cell diameter, protoplast diameter and area, and cell wall thickness and area of fibre bundle cells were calculated from these data. CWA of structural tissues increased in sections up to 75 mm distal to the ligule, confirming the role of cell wall deposition in the increase in SLW (r2 = 0.924; P < or = 0.01). However, protoplast diameter of fibre cells did not decrease significantly as CWA increased, although mean thickness of fibre cell walls increased by 95 % between 15 and 105 mm distal to the ligule. Therefore, secondary cell wall deposition in fibre bundles of tall fescue leaf blades resulted in continued radial expansion of fibre cells rather than in a decrease in protoplast diameter.

Cell Division↗