Long-term Partitioning, Storage and Remobilization of 14C Assimilated by Trifolium repens (cv. Blanca)

The fourth fully expanded leaf on the main stolon of white cloverplants was exposed to ¹⁴CO₂. Thereafter, quantitative and fractionalanalysis of the partitioning, storage and remobilization afterdefoliation of the ¹⁴C labelled assimilate was sequentiallyconducted over a 2- to 3-week period. In undefoliated plants, most ¹⁴C reached its final destinationwithin 24 h of feeding. Forty percent of assimilated ¹⁴C waslost through respiration, while the rest was exported, predominantlyto meristems, but also to roots, stolons and leaves. The ¹⁴Cinitially translocated to meristems was subsequently recoveredin stolon and leaf tissue as the plants matured. Approximately 10% of assimilated ¹⁴C was invested into long-termstorage in roots and stolons. These reserves were remobilizedafter both partial and total defoliation, and a portion of theremobilized ¹⁴C was incorporated into new growth, Partly defoliatedplants regrew more rapidly than totally defoliated plants, butmore ¹⁴C reserve depletion took place in the totally defoliatedtreatment. Reserve depletion took place from both stolons androots, but stolon reserves were preferentially utilized. Bothhigh and low molecular weight storage compounds were involved. Trifolium repens, white clover, assimilate partitioning, storage, remobilization, defoliation     

Partitioning of sugars in Lolium perenne (perennial ryegrass) during drought and on rewatering

Simulated swards of perennial ryegrass ( Lolium perenne ) growing in 1-m³ soil blocks in the glasshouse were either well watered or deprived of water for 57 d and then rewatered. The first aim was to measure effects of drought on sugar (water-soluble carbohydrate) composition of laminae and sheaths of mature laminae, and bases and laminae of young (growing) leaves. The second aim was to use pulse labelling with ¹⁴CO₂ to follow the partitioning of recently-fixed assimilates, and the assembly and consumption of reserve sugars (fructans). Over the last 7 d of drought growth almost stopped, old leaves died faster than they were replaced, and total sugar (which had doubled in concentration during drought) was rapidly consumed. Leaf laminae had lower content of total sugars and of large fructan (DP>5) than did growing bases and sheaths. Drought greatly reduced the rate at which sugar was exported from the laminae to the sheaths and growing leaf bases, and the rate at which it was converted to fructan. Nevertheless, fructan accumulated over the first 50 d of drought. Rewatering did not result in depolymerization and remobilization of sugars that had been formed during the last 7 d of drought, but stimulated their further assembly into high-DP fructans. Our hypothesis, that accumulation of neo-kestose (a DP-3 fructan) in droughted laminae was a symptom of sugar remobilization just before death, was disproved. It is concluded that sugar reserves contribute to drought resistance only under extreme conditions. The specific role of fructan in dry environments might be to improve regrowth when drought is relieved, rather than to enhance growth during drought.     

The Partitioning of Photosynthetically Assimilated 14C into Amino Acids in Wheat 1. Partitioning During Transport to the Grain

When ¹⁴CO₂ was fed to flag leaf laminae at 20 d post-anthesis,the transport organs between the leaf and the grains containedappreciable ¹⁴C in glutamine, glutamate, serine, alanine, threonineand glycine. Smaller amounts of ¹⁴C were present in gamma-aminobutyricacid (GABA), aspartate and cysteine. Other amino acids whichwere labelled in the source leaf were not labelled in the transportorgans. The export of labelled glutamine, serine, glycine andthreonine from the source leaf was favoured in comparison tothe other amino acids mentioned. Threonine accumulated, andwas subsequently metabolised, in the rachis. [¹⁴C]GABA alsoaccumulated in the rachis. In the grains, the relative amountof soluble [¹⁴C]alanine increased with chase time. This wasprobably due to de novo synthesis and reflected the specialrole of alanine in grain nitrogen metabolism. Wheat, Triticum aestivum, ¹⁴CO₂, amino acids, transport, carbon metabolism     

Co-transformed, diploid Lolium perenne (perennial ryegrass), Lolium multiflorum (Italian ryegrass) and Lolium temulentum (darnel) plants produced by microprojectile bombardment

A total of 37 plants (30 Lolium multiflorum Lam., 6 L. perenne L., 1 L. temulentum L.) were regenerated from cell suspension colonies bombarded with plasmid DNAs encoding a hygromycin resistance gene (HYG) expressed under a CaMV35S promoter and a β-glucuronidase (GUS) gene expressed under a truncated rice actin1 promoter and first intron, or a maize ubiquitin promoter and first intron. Resistant plants were regenerated under hygromycin selection and transferred to soil. PCR analysis showed that the co-transformation frequency of the GUS gene varied from 33% to 78% of transformants, while histochemical staining of leaf tissue from soil-grown plants showed that the co-expression frequency varied from 37% to 50%. The transgenic nature of the plants was demonstrated by Southern hybridisation analysis, which also showed that the non-selected (GUS) gene was generally present at a higher copy number than the selected (HYG) gene. Received: 10 October 1997 / Revision received: 18 March 1998 / Accepted: 29 November 1998     

Carbonate recrystallization in root-free soil and rhizosphere of Triticum aestivum and Lolium perenne estimated by 14C labeling

The photo- and bio-degradation of dissolved organic matter (DOM) in water from the Broad River were investigated in laboratory experiments using a solar simulator to control the intensity and exposure of samples to irradiation. The water samples included a natural assemblage of microorganisms, and the daily exposure of samples to irradiation was varied to distinguish the relative contributions of photochemical and biological degradation. Concentrations of dissolved organic carbon (DOC) and specific components of DOM, including chromophoric DOM (CDOM), lignin phenols and amino acids, were monitored to investigate the reactivity and predominant pathway of degradation of these DOM components. Biodegradation was primarily responsible for the overall remineralization of DOC and losses of the amino acid component of DOM, whereas photodegradation was primarily responsible for losses of the chromophoric and lignin phenol components of DOM. The rates of photodegradation of lignin phenols were strongly influenced by the presence of methoxy groups on the aryl ring. Syringyl (S) phenols have two methoxy substitutions, vanillyl (V) phenols have one methoxy substitution, and p-hydroxy (P) phenols are not substituted with methoxy groups. Photochemical decay constants were highest for S phenols, lowest for P phenols and followed a consistent pattern (S > V > P) in the experiments. The carbon-normalized yields of amino acids and lignin phenols were found to be useful molecular indicators of the highly reactive (i.e. labile) components of biodegradable and photodegradable DOM, respectively.     

Uptake of glycine by non-mycorrhizal Lolium perenne.

Plants of Lolium perenne were grown in sterile solution culture. 15N-labelled glycine (Gly) coupled with gas chromatograph mass spectrometry was used to prove that non-mycorrhizal plants of L. perenne are capable of acquiring N in the form of intact Gly. It was estimated that a minimum of 80% of Gly-N uptake, over a 3 h period, was as intact Gly, though possible processes resulting in deviation from this estimate are discussed. The relative incorporation of 15N derived from Gly uptake into serine (Ser) compared with other amino acids in the root amino acid pool suggested the enzyme serine:glyoxylate aminotransferase was at least partly responsible for the synthesis of Ser from Gly. Defoliation was shown to reduce Gly uptake by L. perenne. The addition of either 25 mol x m(-3) sucrose or 50 mol x m(-3) glucose to the uptake solution of defoliated plants increased Gly-N uptake compared with both defoliated plants without sugars and with undefoliated plants. Addition of a glucose analogue, 3-O-methyl-D-glucopyranose, that is absorbed but not metabolized by plants, did not affect Gly uptake by defoliated plants. Increasing pH from 3.5 to 9.2 caused a reduction in Gly uptake. Results of the effects of defoliation and pH are consistent with Gly uptake by L. perenne being by an energy-dependent proton symport. When either or Gly were supplied to plants at equimolar concentrations, uptake was five times greater than that of Gly at pH 6 and 13 times greater at pH 9.     

Assimilation of 14CO2 by the Inflorescence of Poa annua L. and Lolium perenne L.

The relative assimilatory activity of the inflorescence, itsindividual components, and the leaves of flowering tillers ofPoa annua L. and Lolium perenneL. was determined over the periodfrom inflorescence emergence to seed shedding. The pattern of¹⁴CO₂ fixation was similar for both species and the inflorescencewas by far the most important assimilatory organ of the reproductivetiller, particularly over the latter period of seed developmentas leaf senescence progressed. With the exception of the seedsall parts of the inflorescence showed significant assimilatoryactivity and the lemmas and paleas accounted for 40–50per cent of the total ¹⁴C fixed by the inflorescence in bothspecies. The importance of the grass inflorescence as a photosyntheticstructure is discussed in relation to similar studies on cereals. Poa annua, Lolium perenne, carbon dioxide assimilation, inflorescence     

Induction of cytoplasmic male-sterility into ryegrass (Lolium perenne)

Summary Data are presented which indicate that a cytoplasmic/genetic type male sterility has been induced into backcross progeny derived from intergeneric hybridization between Festuca pratensis (female parent) and Lolium perenne. Large numbers of male sterile genotypes have been obtained in all the backcross generations examined. The frequency and purity of maintainer genotypes is low and requires further breeding and selection. Analysis of data suggest that at least two loci are involved in fertility restoration. Conclusions regarding the genetic model are tentative and require further analyses.     

The typification of Lolium perenne L. and Loliutn temulentum L. (Poaceae)

LOOS, B. P. & JARVIS, C. E., 1992. The typification of Lolium perenne and Lolium temulentum (Poaceae). The typification of the Linnaean species Lolium perenne and Lolium temulentum has been studied. Lolium perenne is typified by material in LINN, as proposed by Terrell, but it has been necessary to select a lectotype for L. temulentum , and material in the Burser herbarium (UPS) has been chosen for this purpose. The study shows that although Linnaeus used awns as a diagnostic character to distinguish the two species, he was aware of the intraspecific variability in this character.     

Deamination of 4-Aminopyrimidine Nucleosides by Extracts of Rye Grass (Lolium perenne)

A deaminase specific for 4-aminopyrimidine nucleosides has been found in rye grass. Lolium perenne. The pH optimum, temperature stability, Km values and specificity was determined.

A new and more accurate method for following the course of deamination is reported. This method depends on the shift in maximum absorbance wavelength of the mixture containing the 4-aminopyrimidine nucleoside and its deaminated product.

     

Development of phosphogluco-isomerase isozymes in perennial ryegrass (Lolium perenne)

The development of isozymes of phosphogluco-isomerase (PGI; D-glucose-6-phosphate ketol isomerase EC 5.3.1.9.) in perennial ryegrasses was followed from dry seed through to leaf senescence using starch gel electrophoretic separations. Root isozymes were also examined. Two forms of the enzyme were found, one (PGI/2) being present in all tissues and at all stages of the life cycle. The other (PGI/1) had two zones of activity, one of which was detected only in light-exposed tissue. Normal development of this form could be inhibited by growing seedlings on distilled water. Some alleles of PGI/2 not previously reported for ryegrasses are also described.     

Effects of zinc and influence of Acremonium lolii on growth parameters, chlorophyll a fluorescence and antioxidant enzyme activities of ryegrass (Lolium perenne L. cv Apollo)

The effects of zinc on growth, mineral content, chlorophyll a fluorescence, and detoxifying enzyme activity (ascorbate peroxidase (APX), EC 1.11.1.11; superoxide dismutase (SOD), EC 1.15.1.1) of ryegrass infected or not by Acremonium lolii, and treated with nutrient solution containing 0-50 mM ZnSO(4) were studied. The introduction of zinc induces stress with a decrease in growth at 1, 5 and 10 mM ZnSO(4) and a cessation of growth at 50 mM ZnSO(4), in ryegrass plants infected by A. lolii or not. This decrease in growth may be due to an accumulation of zinc in leaves. Nevertheless, symbiotic plants showed higher values in tiller number, an advantage conferred by the fungus. After 24 d of Zn exposure, leaf fresh weights and leaf water content were lower in plants growing with Zn in the culture medium and no advantage was conferred by the fungus to its host. An increase in Zn supply resulted in a decrease of the Ca, K, Mg, and Cu content of the leaves, a reduction in the quantum yield of electron flow throughout photosystem II (DeltaF/F(1)(m))and a lowering of the efficiency of photosynthetic energy conversion (F(v)/F(m)), compared to control plants. To counter this zinc stress, detoxifying enzymes APX and SOD increased (100%) when Zn reached the value of 50 mM in the nutrient solution. At 10 mM ZnSO(4), the presence of the fungus in the plant led to an increase in the threshold toxicity of plants to zinc by a diminution of APX activity.     

Growth of Ryegrass (Lolium perenne L.) Exposed to SO2: II. CHANGES IN THE DISTRIBUTION OF PHOTO ASSIMILATED 14C

Perennial ryegrass (Lolium perenne L.) cv. S23 was exposed to0, 50, and400 µg m– ³ SO₂ for a 29 d period, harvested,and then exposed under the same regime for a further 22 d periodof regrowth. Leaves from plants representing each exposure concentrationwere photosynthetically fed ¹⁴CO₂ for 5 min at the end of eachperiod. A significant increase in photoassimilation of ¹⁴CO₂and retention of ^I4C, concomitant with significant decreasesin [¹⁴C]glycine and [¹⁴C]serine with increasing SO₂ concentration,implied that there was an inhibition of the photorespiratorypathway. At the second harvest, leaves from plants exposed to400 µg m– ³ SO₂ also exhibited significant increasesin [¹⁴C]sucrose and [¹⁴C]fructose.     

黑麦草(Lolium perenne L.)内生真菌的检测、分离及鉴定

从多年生黑麦草(LoliumperenneL.)5个品种———SR4000、Pinnacle、Topgun、CalypsoⅡ、Justus中分离出61个菌株。次培养后,所得形态稳定的菌株可分为4个形态群,依据其形态特征及APPCR的结果,确定其中的57个分离菌株为Neotyphodiumlolii。     

The Partitioning of Photosynthetically Assimilated 14C into Amino Acids in Wheat: 2. Distribution in Amino Acids of Wheat Grain Fractions

Changes in the distribution of ¹⁴C between free and bound aminoacids in wheat grains (Triticum aestivum L. cv. Arkas) at 10and 20 d post-anthesis are described. After ¹⁴CO₂, labellingof the flag leaf, ¹⁴C was initially more rapidly transferredto the grains of 20 d post-anthesis plants than for 10 d post-anthesisplants. However, after a 460 min chase period in the light theamount of ¹⁴C in the grains of the younger and older plantswere similar. In the younger, more rapidly growing grains, agreater proportion of the ¹⁴C was incorporated into structuraltissue and starch. ¹⁴C accumulation in the grains continuedduring the dark in the younger grains but not in the older grains. Although the overall ¹⁴C distribution between the free aminoacid and protein pools of the grain was similar for both treatments,the distribution within the albumin, prolamin and globulin fractionsand between the individual non-bound amino acids differed. Ofthe protein fractions, the albumins were initially the mostheavily labelled but after 460 min chase the prolamins containedmore ¹⁴C. The majority of the ¹⁴C in the albumin and globulinfractions after 280 min chase was in hydrolysable, non-aminoacid compounds. In both tissues, the free amino acid pools lostradioactivity in the dark but the solid residues and proteinscontinued to function as ¹⁴C sinks. Daily fluctuations in the radioactivity in free and bound alanineare consistent with the role of free alanine as a diurnal metabolicnitrogen pool. Wheat, Triticum aestivum¹⁴CO₂, amino acids, proteins, carbon metabolism     

Influence of initial levels of carbohydrates, fructans, nitrogen, and soluble proteins on regrowth of Lolium perenne L. cv. Bravo following defoliation

An experiment was designed to evaluate the role of N and C reserves on regrowth of Lolium perenne cv. Bravo following defoliation. By using two nitrogen fertilization levels together with three photoperiodic conditions, plants with variable contents of water-soluble carbohydrates (43-216 mg g^-1 DW in stubble) and contrasting amounts of nitrogen (7-49 mg g^-1 DW) were obtained. Plants were severely defoliated and regrowth was followed for 28 d under the same environmental conditions. The yield of leaf dry matter at the end of the regrowth period was not related to the initial level of carbohydrate reserves. However, levels of fructan in leaf sheaths and in elongating leaf bases strongly influenced the shoot yield during the first 2 d following defoliation. Fructan exohydrolase activity increased 2-3-fold in sheaths and 3.5-5-fold in elongation leaf bases, suggesting that not only fructans from sheaths but also fructans from immature cells may be used as substrates for growth. In contrast, no direct relationship was found between shoot production and nitrogen or soluble protein accumulation in source organs during early regrowth. A significant correlation existed with the initial amount of soluble proteins in sheaths and in elongating leaf bases after only 6 d of regrowth.     

Isolation and partial characterization of two antigenic glycoproteins from rye-grass (Lolium perenne) pollen.

Two glycoproteins have been purified from a buffer extract of rye-grass (Lolium perenne) pollen. Both migrated as single bands on sodium dodecyl sulphate/polyacrylamide gels. Glycoprotein 1 (0.8 mg/g of pollen) had a apparent mol.wt. of 33 000 and contained 95% protein and 5% carbohydrate. The monosaccharides glucose, galactose, mannose, arabinose and N-acetylglucosamine were present in the proportions 3:3:1:2:1. Glycoprotein 2 (0.4 mg/g of pollen) had an apparent mol. wt. of 68000 and contained 88% protein and 12% carbohydrate. The monosaccharides glucose, galactose, mannose, fucose, xylose, arabinose and N-acetylglucosamine were present in the proportions 4:7:13:5:8:6:6. This glycoprotein bound concanavalin A and Lotus tetragonolobus (asparagus pea) lectin. Radioallergosorbent (RAST) inhibition tests showed that Glycoprotein 1 is an effective allergen, whereas Glycoprotein 2 has less allergenic activity. A method for performing both lectin-binding assays and RAST inhibition tests using microtitre trays is described.     

Physicochemical characterization of cellulose from perennial ryegrass leaves (Lolium perenne)

In this study, we investigated the physicochemical properties of the cellulosic preparations obtained from both untreated perennial ryegrass leaves and de-juiced leaves. It was found that treatment at 22 degrees C with 18% NaOH and 18% KOH for 2h, and 10% NaOH and 10% KOH for 16 h yielded 28.2%, 28.8%, 22.7%, 23.4%, respectively, of 'cellulose' residue from untreated ryegrass leaves and 35.7%, 36.8%, 32.8% and 34.6%, respectively, from the de-juiced leaves. For each cellulosic fraction, the glucose content was 71.6%, 69.6%, 67.8%, 66.7%, 69.7%, 68.6%, 63.9% and 61.7%, respectively. The structure of the cellulose samples was examined using FTIR and CP/MAS (13)C NMR spectroscopy and X-ray diffraction. The cellulosic preparations were free of bound lignin except for noticeable amounts of residual hemicelluloses (28.4-38.3%), and had intrinsic viscosities between 275.1 and 361.0 mL/g, along with molecular weights from 144,130 to 194,930 g/mol. This study found that the cellulose samples isolated from both de-juiced ryegrass leaves and the untreated leaves had a much lower percent crystallinity (33.0-38.6%) than that from wood-based fibres (60-70%) and had much shorter fibres (0.35-0.49 mm) than those of either cereal straws, bagasse or wood. In addition, a partial disruption of the hydrogen bonds and microfibrils may occur during the de-juicing process by mechanical activity, which results in a decreased cellulose crystallinity and fibre length. These findings are significant in relation to hydrolysing ryegrass cellulose for bio-ethanol production.