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The contamination of soil and water by metals such as mercury (Hg) and cadmium (Cd) has been increasing in recent years, because of anthropogenic activities such as mining and agriculture, respectively. In this work, the changes in the rhizosphere microbiome of Lolium perenne L. during the phytoremediation of soils contaminated with Hg and Cd were evaluated. For this, two soil types were sampled, one inoculated with mycorrhizae and one without. The soils were contaminated with Hg and Cd, and L. perenne seeds were sown and harvested after 30 days. To assess changes in the microbiome, DNA isolation tests were performed, for which samples were subjected to two-step PCR amplification with specific 16S rDNA V3-V4 primers (337F and 805R). With mycorrhizae, changes had been found in the absorption processes of metals and a new distribution. While with respect to microorganisms, families such as the Enterobacteriaceae have been shown to have biosorption and efflux effects on metals such as Hg and Cd. Mycorrhizae then improve the efficiency of removal and allow the plant to better distribute the absorbed concentrations. Overall, L. perenne is a species with a high potential for phytoremediation of Cd- and Hg-contaminated soils in the tropics. Inoculation with mycorrhizae modifies the phytoremediation mechanisms of the plant and the composition of microorganisms in the rhizosphere. Mycorrhizal inoculation and changes in the microbiome were associated with increased plant tolerance to Cd and Hg. Microorganism-assisted phytoremediation is an appropriate alternative for L. perenne. [ABSTRACT FROM AUTHOR]

With developments in industry, petroleum and heavy metal pollution are increasingly affecting soil, significantly harming the environment, biosecurity, and human health. Therefore, the remediation of contaminated soil is becoming increasingly important. In this study, ryegrass (Lolium perenne L.) was planted in petroleum–heavy metal co-contaminated soil with the application of nitrogen and phosphorus fertilizers. Three treatments were set up: uncontaminated soil + ryegrass (SH); petroleum–heavy metal co-contaminated soil + ryegrass (SPGH); and petroleum–heavy metal co-contaminated soil + ryegrass + nitrogen and phosphorus fertilizer (SPGH + NP). The results showed that the petroleum–heavy metal co-contamination promoted increases in the root length, surface area, volume, and diameter of ryegrass roots, increasing the below-ground biomass and decreasing the photosynthetic pigment content in the early stages of the experiment. The ratios of chlorophyll a/b and chlorophyll/carotenoid also increased. However, the application of fertilizer reduced the length, surface area, volume, and diameter of ryegrass roots in the co-contaminated soil, and the below-ground biomass decreased while the above-ground biomass increased. Furthermore, the photosynthetic pigment content was significantly higher than that in the unfertilized treatment and the chlorophyll a/b ratio decreased while the chlorophyll/carotenoid ratio increased. Therefore, fertilizers could alleviate the toxic effects of petroleum–heavy metal combined pollution on ryegrass roots and promote the synthesis of chlorophyll and other pigments, thus reducing the inhibitory effect of petroleum–heavy metal combined pollution on ryegrass growth and facilitating the remediation of the polluted soil. [ABSTRACT FROM AUTHOR]

Physical fractionation of a municipal solid waste compost was performed by a dry sieving process to obtain two particle size fractions (> 1.6 mm and 0.8–1.6 mm). The compost with the two particle sizes and the whole unfractionated compost were applied to field soil, and the effect of different size fractions of compost on the growth and physiological characteristics of Lolium perenne L. were investigated. The results showed that the plant height and shoot biomass of L. perenne were higher in the treatments with the whole compost and > 1.6 mm size fraction compared with the control throughout the growing season, but the difference between treatments decreased gradually. The chlorophyll content in these two treatments was also higher than that in the control. The biomass, chlorophyll b, and total chlorophyll content of the second harvest were 23.8%, 82.1%, and 13.9%, respectively, higher in the > 1.6 mm size fraction treatment than in the control. In addition, L. perenne had a dark green color and uniform plants in the > 1.6 mm fraction treatment, which scored the highest in the comprehensive evaluation of turf quality. Plants treated with the coarse fraction of > 1.6 mm showed a strong photosynthetic capacity and maintained a high protective enzyme activity and proline content to improve stress resistance. [ABSTRACT FROM AUTHOR]

The successful introduction of isopentenyl transferase (IPT) gene into perennial ryegrass, cultivars Numan and Grassland using Agrobacterium tumefaciens via three explants (callus, seed and meristem tip) under three individual experiment was evaluated. In the first experiment, the calli were inoculated with LBA4404 Agrobacterium strain under vacuum, heat and in combination of both at 42 °C for 5 min followed by vacuum treatment (390 mm Hg pressure) for 15 min. Sonication-assisted Agrobacterium-mediated transformation (SAAT) was applied for seed and meristem tip transformation of perennial ryegrass for the first time. Results showed positive effects of heat treatment on transformation efficiency during Agro-infection in both cultivars. However, heat shock treatment was more effective in ʻGrasslandʼ than ʻNumanʼ (14.2% vs 9.2%). In addition, high transformation efficiency of about 46.65% and 29.15% was observed using meristem tip explants of ʻGrasslandʼ and ʻNumanʼ based on IPT and RD29A positive PCR results, respectively. Seed transformation efficiency in ʻGrasslandʼ and ʻNumanʼ under SAAT method reached to 37.5% and 16.65%, respectively. Results of these experiments revealed that LBA4404 strain was more efficient than GV3101 in transformation of both perennial ryegrass cultivars. The DNA-blot analysis confirmed that a single T-DNA copy of the IPT gene was integrated into the genomic DNA of the positive transgenic T0 plants which obtained from callus and meristem tip explants of ʻGrasslandʼ after heat and SAAT treatment, respectively. Because monocots are not the host of Agrobacterium tumefaciens, this novel protocol can be used in further experiments on genetic transformation of perennial ryegrass cultivars. [ABSTRACT FROM AUTHOR]

Alkaloid concentration of perennial ryegrass herbage is affected by endophyte strain and host plant genotype. However, previous studies suggest that associations between host and endophyte also depends on environmental conditions, especially those affecting nutrient reserves and that water-soluble carbohydrate (WSC) concentration of perennial ryegrass plants may influence grass-endophyte associations. In this study a single transgenic event, with altered expression of fructosyltransferase genes to produce high WSC and biomass, has been crossed into a range of cultivar backgrounds with varying Epichloë endophyte strains. The effect of the association between the transgenic trait and alkaloid production was assessed and compared with transgene free control populations. In the vast-majority of comparisons there was no significant difference between alkaloid concentrations of transgenic and non-transgenic plants within the same cultivar and endophyte backgrounds. There was no significant difference between GOI+ (gene of interest positive) and GOI− (gene of interest negative) populations in Janthritrem response. Peramine concentration was not different between GOI+ and GOI− for 10 of the 12 endophytes-cultivar combinations. Cultivar Trojan infected with NEA6 and Alto with SE (standard endophyte) exhibited higher peramine and lolitrem B (only for Alto SE) concentration, in the control GOI− compared with GOI+. Similarly, cultivar Trojan infected with NEA6 and Alto with NEA3 presented higher ergovaline concentration in GOI−. Differences in alkaloid concentration may be attributable to an indirect effect in the modulation of fungal biomass. These results conclude that the presence of this transgenic insertion, does not alter the risk (toxicity) of the endophyte-grass associations. Endophyte-host interactions are complex and further research into associations with high WSC plant should be performed in a case by case basis. [ABSTRACT FROM AUTHOR]

Aims: During the first days after harvest of Lolium perenne L., N remobilized from roots and stubble forms the main N source for regrowth. Low N uptake from the soil during this period may lead to N loss if N fertilizer is applied too soon. Furthermore, temporary N deprivation has been found to stimulate root growth. We therefore hypothesized that a strategic delay in N application after harvest may improve N-use efficiency of L. perenne grassland by increasing root biomass and reducing N loss. Methods: In a laboratory and field experiment with L. perenne, we delayed N fertilizer application after harvest for 0, 3, 6, 9 and 12 days, repeated this for up to six harvest cycles, and determined effects on herbage yield, herbage N uptake and root biomass. Results: In both experiments, delaying N application for up to 12 days had no significant effect on root biomass or total herbage N uptake, but it significantly reduced total herbage yield in the laboratory experiment. Total yield tended to be highest when N application was delayed for 3 days. Two growth periods in the field experiment showed significantly higher N uptake when N application was delayed, possibly due to rainfall-induced N losses in the treatments with shorter delay. Conclusions: Our results do not provide evidence that delaying N application improves N-use efficiency of L. perenne grassland by increasing root biomass. However, strategic timing of N fertilizer application based on rainfall forecasts could contribute to improve N-use efficiency by reducing N losses from leaching and denitrification. [ABSTRACT FROM AUTHOR]

White clover/perennial ryegrass mixtures ( Trifolium repens L., Lolium perenne L.) are potential understory candidates for temperate agroforestry systems. A 2-year artificial shade experiment was conducted to determine the effects of shade on herbage production and quality and on changes in sward composition under field conditions. Wooden frames covered by shade cloth or a slatted structure were used on the sward to mimic different shade patterns of trees. The sward was exposed to 30, 50, and 80 % reduction in sun irradiance as well as a non-shaded control (0 % reduction). Total annual herbage production was highest in non-shaded swards in second and third year after establishment (8 and 16 t DM ha, respectively) and declined with increased shade (up to 70 % with 80 % shade). Compared to the control (24 t ha), 50 % shade cloth and 50 % slatted structure reduced biennial herbage production by 4 and 7 t ha, respectively. A decline in clover content of up to 93 % under severe shade compared to the control in the second year of the field experiment highlighted the sensitivity of clover to reduced radiation. No differences in forage nutritive qualities were detected in response to shade intensity during either growing season. On a dry matter basis, average biennial quality values were 2.7 % N, 41.8 % NDF, 34.4 % ADF, and 4.7 % ADL. The findings of the biennial field experiment confirm a white clover/perennial ryegrass sward is a suitable understory under light to moderate shade conditions; however, within a temperate agroforestry practice under dense shade, sward productivity and clover content will rapidly decline. Long-term effects of shade on white clover/perennial ryegrass mixtures as an understory in temperate agroforestry systems need to be evaluated in future research activities. [ABSTRACT FROM AUTHOR]

The effects of sodium nitroprusside (SNP, a donor of NO) on cadmium (Cd) toxicity in ryegrass seedlings ( Lolium perenne L.) were studied by investigating the symptoms, plant growth, chlorophyll content, lipid peroxidation, H-ATPase enzyme and antioxidative enzymes. Addition of 100 μM CdCl caused serious chlorosis and inhibited the growth of ryegrass seedlings, and dramatically increased accumulation of Cd in both shoots and roots, furthermore, the absorption of macro and micronutrients were inhibited. Addition of 50, 100, 200 μM SNP significantly decreased the transport of Cd from roots to shoots, alleviated the inhibition of K, Ca, Mg and Fe, Cu, Zn absorption induced by Cd, reduced the toxicity symptoms and promoted the plant growth. The accumulation of reactive oxygen species (ROS) significantly increased in ryegrass seedlings exposed to Cd, and resulted in the lipid peroxidation, which was indicated by accumulated concentration of thiobarbituric acid-reactive substances. Addition of 50, 100, 200 μM SNP significantly decreased the level of ROS and lipid peroxidation. Activities of antioxidant enzymes also showed the same changes. Addition of 50, 100, 200 μM SNP increased activities of superoxide dismutase, peroxidase, catalase and ascorbate peroxidase in ryegrass seedlings exposed to Cd. Addition of 100 μM SNP had the most significant alleviating effect against Cd toxicity while the addition of 400 μM SNP had no significant effect with Cd treatment. [ABSTRACT FROM AUTHOR]

This study was conducted to investigate the combined effects of elevated CO levels and cadmium (Cd) on the root morphological traits and Cd accumulation in Lolium multiflorum Lam. and Lolium perenne L. exposed to two CO levels (360 and 1 000 μl/L) and three Cd levels (0, 4, and 16 mg/L) under hydroponic conditions. The results show that elevated levels of CO increased shoot biomass more, compared to root biomass, but decreased Cd concentrations in all plant tissues. Cd exposure caused toxicity to both Lolium species, as shown by the restrictions of the root morphological parameters including root length, surface area, volume, and tip numbers. These parameters were significantly higher under elevated levels of CO than under ambient CO, especially for the number of fine roots. The increases in magnitudes of those parameters triggered by elevated levels of CO under Cd stress were more than those under non-Cd stress, suggesting an ameliorated Cd stress under elevated levels of CO. The total Cd uptake per pot, calculated on the basis of biomass, was significantly greater under elevated levels of CO than under ambient CO. Ameliorated Cd toxicity, decreased Cd concentration, and altered root morphological traits in both Lolium species under elevated levels of CO may have implications in food safety and phytoremediation. [ABSTRACT FROM AUTHOR]

Variability and future alterations in regional and global climate patterns may exert a strong control on the carbon dioxide (CO) exchange of grassland ecosystems. We used 6 years of eddy-covariance measurements to evaluate the impacts of seasonal and inter-annual variations in environmental conditions on the net ecosystem CO exchange (NEE), gross ecosystem production (GEP), and ecosystem respiration (ER) of an intensively managed grassland in the humid temperate climate of southern Ireland. In all the years of the study period, considerable uptake of atmospheric CO occurred in this grassland with a narrow range in the annual NEE from −245 to −284 g C m y, with the exception of 2008 in which the NEE reached −352 g C m y. None of the measured environmental variables (air temperature (Ta), soil moisture, photosynthetically active radiation, vapor pressure deficit (VPD), precipitation (PPT), and so on) correlated with NEE on a seasonal or annual scale because of the equal responses from the component fluxes GEP and ER to variances in these variables. Pronounced reduction of summer PPT in two out of the six studied years correlated with decreases in both GEP and ER, but not with NEE. Thus, the stable annual NEE was primarily achieved through a strong coupling of ER and GEP on seasonal and annual scales. Limited inter-annual variations in Ta (±0.5°C) and generally sufficient soil moisture availability may have further favored a stable annual NEE. Monthly ecosystem carbon use efficiency (CUE; as the ratio of NEE:GEP) during the main growing season (April 1-September 30) was negatively correlated with temperature and VPD, but positively correlated with soil moisture, whereas the annual CUE correlated negatively with annual NEE. Thus, although drier and warmer summers may mildly reduce the uptake potential, the annual uptake of atmospheric CO, in this intensively managed grassland, may be expected to continue even under predicted future climatic changes in the humid temperate climate region. [ABSTRACT FROM AUTHOR]

Ice recrystallization inhibition (IRI) proteins are thought to play an important role in conferring freezing tolerance in plants. Two genes encoding IRI proteins, LpIRI- a and LpIRI- b, were isolated from a relatively cold-tolerant perennial ryegrass cv. Caddyshack. Amino acid alignments among the IRI proteins revealed the presence of conserved repetitive IRI-domain motifs (NxVxxG/NxVxG) in both proteins. Quantitative reverse transcriptase PCR (qRT-PCR) analysis indicated that LpIRI- a was up-regulated approximately 40-fold while LpIRI- b was up-regulated sevenfold after just 1 h of cold acclimation, and by 7 days of cold acclimation the transcripts had increased 8,000-fold for LpIRI- a and 1,000-fold for LpIRI- b. Overexpression of either LpIRI- a or LpIRI- b gene in Arabidopsis increased survival rates of the seedlings following a freezing test under both cold-acclimated and nonacclimated conditions. For example, without cold acclimation a −4°C treatment reduced the wild type’s survival rate to an average of 73%, but resulted in survival rates of 85–100% for four transgenic lines. With cold acclimation, a −12°C treatment reduced the wild type’s survival rate to an average of 38.7%, while it resulted in a survival rate of 51–78.5% for transgenic lines. After cold acclimation, transgenic Arabidopsis plants overexpressing either LpIRI- a or LpIRI- b gene exhibited a consistent reduction in freezing-induced ion leakage at −8, −9, and −10°C. Furthermore, the induced expression of the LpIRI-a and LpIRI-b proteins in transgenic E. coli enhanced the freezing tolerance in host cells. Our results suggest that IRI proteins play an important role in freezing tolerance in plants. [ABSTRACT FROM AUTHOR]

Winter hardiness is a quantitative trait and the lack of it limits geographic distribution of ryegrass. Improving winter hardiness is an important breeding goal in ryegrass breeding programs. An understanding of the genetic basis for the component traits of winter hardiness would allow more efficient selection. A three-generation interspecific population of an annual × perennial ryegrass consisting of 152 progenies was used to map quantitative trait loci (QTL) that control winter hardiness-related traits including fall growth (FG), freezing tolerance (FT), and winter survival (WS) over 2 years. A total of 39 QTL were identified for the three traits from both the female parental (MFA) and the male parental (MFB) maps, of which 13 were for FG, 6 for FT, and 20 for WS. The proportion of phenotypic variation explained by individual QTL ranged from 10.4 to 22.1%. Both FG and FT were positively correlated with WS. Common QTL were detected between FG, FT, and WS. The QTL associated with WS on linkage groups (LGs) 4 and 5, and the QTL for FT on LG 5 were consistently identified over years and maps. These consistent QTL might serve as potential tools for marker-assisted selection to improve ryegrass winter hardiness. [ABSTRACT FROM AUTHOR]

Annual ( Lolium multiflorum Lam.) and perennial ( Lolium perenne L.) ryegrasses are two important forage and turfgrass species. Improving the digestibility of forage by decreasing fiber content is a major goal in forage crop breeding programs. An annual × perennial ryegrass interspecific hybrid population was used to map quantitative trait loci (QTLs) for fiber components, neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL), and crude protein (CP). Samples were harvested three times in August and September 2003 and August 2004, respectively. Simple interval mapping was used to detect QTLs from both the male and female parental maps previously developed for the population. Fiber components were all correlated positively with each other and were negatively correlated with CP. The largest correlations were between NDF and ADF with r = 0.86, 0.72, and 0.82 for each of the three harvests. All four traits showed intermediate broad-sense heritability values ranging from 0.35 to 0.72. A total of 63 QTLs were detected for the four traits measured over the three harvests from both the female and male maps. Coincident QTLs were detected on linkage groups (LGs) 2, 6, and 7 for NDF, LGs 1, 2, and 7 for ADF, LGs 6 and 7 for ADL, and LG 2 for CP, respectively. Coincident QTLs were also detected on LGs 2, 6, and 7 for NDF and ADF, providing evidence of the genetic basis of the observed high level of phenotypic correlation. The QTLs on LGs 2, 6, and possibly 7 for fiber components were co-located on the same LG as several lignin biosynthetic genes from perennial ryegrass. [ABSTRACT FROM AUTHOR]

The dehydration- responsive element binding proteins (DREB1)/ C-repeat (CRT) binding factors (CBF) function as transcription factors and bind to the DRE/CRT cis-acting element (core motif: G/ACCGAC) commonly present in cold-regulated ( COR) genes and subsequently upregulate the expression of such genes in Arabidopsis. We identified a DREB1A/CBF3-like gene, designated LpCBF3, from perennial ryegrass ( Lolium perenne L.) by using RT-PCR and RACE (rapid amplification of cDNA end). The LpCBF3 gene contains all the conserved domains known to exist in other CBF genes. A comprehensive phylogenetic analysis using known and computationally identified CBF homologs in this study revealed that all monocot CBF genes are separately clustered from eudicot CBF genes and the LpCBF3 is the ortholog of rice OsDREB1A/CBF3 gene. Similar to other DREB1A/CBF3 homologs, expression of the LpCBF3 is induced by cold stress, but not by abscisic acid (ABA), drought, or salinity. Overexpression of the LpCBF3 cDNA in Arabidopsis induced expression of the Arabidopsis DREB1A/CBF3 target COR genes, COR15a and RD29A, without cold acclimation. Ion leakage in leaves of the overexpression transgenic plants was significantly reduced, an indication of enhanced freezing tolerance. Our data demonstrated that LpCBF3 not only resembles DREB/CBF genes of Arabidopsis, but is also capable of functioning as a transcriptional regulator in Arabidopsis, a species distant to the grass family. [ABSTRACT FROM AUTHOR]

Perennial ryegrass ( Lolium perenne L.) is the most important grass species for temperate grassland agriculture. The level and distribution of genetic variation in gene bank ecotype collections is still largely unknown but of great interest for the planning of breeding programs. The objectives of this study were to (i) assess the molecular diversity of Polish ecotypes of perennial ryegrass, and (ii) compare the relationship between this group and German ecotypes and European cultivars investigated previously. A total number of 166 polymorphic marker bands were detected among the 171 individual plants of the 9 Polish ecotypes. In a joint analysis with 9 Polish and 22 German ecotypes, and 22 European cultivars 172 polymorphic RAPD markers could be found. Genetic distance among the Polish ecotypes ranged from 0.31 to 0.51, while for all 53 populations a broader range was detected (0.25–0.67). An analysis of molecular variance (AMOVA) revealed a much larger variation within populations (71%) than among them (29%). The Polish ecotypes contained the highest within population variation (74%). The largest among group difference (15%) was found between the Polish ecotypes versus all other accessions. We conclude that the Polish ecotypes represent a valuable genetic resource for enlarging the genetic variation in the West European germplasm pool of perennial ryegrass. [ABSTRACT FROM AUTHOR]

Silvopastoral systems comprise part of the continued expansion of conifer plantings on grassland in New Zealand. Greater understanding of the short term dynamics of soil organic P in such systems will further our knowledge about soil carbon and phosphorus relationships which will enable improved nutrient management in the field. A glasshouse experiment was carried out to examine the short-term effects (36 weeks) of combinations of radiata pine (Pinus radiata), lucerne (Medicago sativaL.) and perennial ryegrass (Lolium perenneL.) grown in the same soil type with a range of carbon (C) and phosphorus (P) levels on plant P uptake and the specific mineralisation rate (SMR). The SMR is defined as net mineralisation rate (i.e. gross mineralisation less microbial and geochemical uptake) and calculated from organic P decline as a percentage of organic P in the original soil before planting. This included an investigation of the effect of tree ectomycorrhizal (EM) hyphae on soil organic P. Plant P uptake was positively correlated with water soluble organic carbon (WSOC) and SMR, which in turn was closely related to soil C levels. The soils with high WSOC and C levels (which also contained high levels of labile inorganic and organic P) enabled high P uptake. Although P uptake was the greatest under radiata pine, the trees tended to deplete inorganic P to a lesser extent than the forages. When tree and forage species were combined, P uptake by forages was similar to when the forages were grown alone. The various soil and plant treatments significantly affected SMR. The two low C soils, showed the greatest organic P mineralisation while a high C soil, which contained significant levels of bicarbonate extracted inorganic P at planting and was under a long established undisturbed pasture, showed the least mineralisation. Trees grown alone showed the greatest SMR, EM hyphae and trees with lucerne were slightly lower than trees alone, while the forages showed the lowest SMR. The findings of this study showed that changes in organic P are strongly influenced by interactions between plant species (radiata pine, lucerne, ryegrass) and soil properties as determined by land use and management. [ABSTRACT FROM AUTHOR]

Polymorphisms in electrophoretic patterns obtained by isoelectric focusing (IEF) were examined to evaluate their suitability for cultivar identification in perennial ryegrass ( Lolium perenne L.). It was possible to discriminate 64 (94%) of 68 cultivars by combining results from esterase and total protein analysis. Discrimination was based on quantitative differences (relative band intensity) rather than on qualitative differences (presence or absence of bands). Esterase patterns from different recent (fresh to seven years old) seed lots of the same perennial ryegrass cultivars were very stable. Occasionally, minor differences in band intensity were observed between recent and old (up to 30 years old) seed lots of a cultivar. Storage of meal samples up to two years at −20 °C had no effect on the total protein patterns. No correlation was found between esterase patterns and ploidy level, cultivar type (pasture or turf), heading date or breeding company. Esterase patterns appeared to be unsuitable markers for the selection of reference cultivars for distinctiveness, uniformity, and stability (DUS) testing, because no correlation was found between cultivars on the basis of esterase banding patterns and morphological characteristics. [ABSTRACT FROM AUTHOR]

Three widely used cultivars of each of the species Festuca pratensis Huds., Lolium perenne L., and Dactylis glomerata L. were investigated by means of randomly amplified polymorphic DNA (RAPD) markers and vegetative growth traits in order to investigate genetic variability within each cultivar and to compare the level of diversity among cultivars and species. RAPD markers allowed a clear separation of the three species. Genetic variability based on RAPD markers was considerably lower for F. pratensis cultivars than for L. perenne and D. glomerata cultivars which showed similar levels of variability. The proportion of variability due to variation within cultivars, determined by an analysis of molecular variance, was lower in F. pratensis (64.6%) than in L. perenne (82.4%) and D. glomerata (85.1%). A comparison of F. pratensis and L. perenne, based on vegetative growth traits, confirmed the differences in genetic variability within cultivars. F. pratensis showed lower coefficients of genetic variation for eight of ten traits when compared to L. perenne. This study demonstrates considerable differences in genetic variability which may have consequences for the adaptability and persistency of individual cultivars. [ABSTRACT FROM AUTHOR]

Stable transformation of perennial ryegrass ( Lolium perenne L.) was achieved by biolistic bombardment of a non embryogenic cell suspension culture, using the hpt and gusA gene. The transformation yielded on the average 5 callus lines per bombardment (1.4×10 cells). Stable integration of the genes into the plant genome was demonstrated by Southern analysis of DNA, isolated from hygromycin-resistant callus lines. The gusA reporter gene, which was regulated by the constitutive promoter of the rice gene GOS2, was expressed in both transient and stable transformation assays, indicating that this promoter is suitable for expression of a transferred gene in perennial ryegrass. Long-term GUS expression was observed in ca. 40% of the callus lines, whereas the other callus lines showed instability after 6 months and 1 year of culture. [ABSTRACT FROM AUTHOR]

The Plant Genetic Resources Unit (PGRU) of the Institute of Grassland and Environmental Research, Welsh Plant Breeding Station (IGER, WPBS), UK, and the Grassland Research Station, ZubrŨí (GRS, Z), in 1992 part of OSEVA Research Institute for Fodder Crops, Troubsko (OSEVA, RIFC), Czechoslovakia, carried out a collaborative plant collecting expedition in Czechoslovakia between 10 August and 29 August 1992. 14 geographical sub-regions of Czechoslovakia were covered with centres of collection in Bohemia, Moravia and Slovakia. The expedition concentrated on a range of vegetation from managed semi-natural grassland to wild, un-managed grassland. The IGER team collected mainly vegetative samples and the GRS, Z team collected seed samples of forage grass and legume populations. Detailed collection site data was recorded at every site. Samples were collected from 67 sites. Vegetative collections of Lolium spp. (34 populations) and Trifolium spp. (39 populations) and seed collectio ns of other species (57 populations) were made by the IGER team. Seed collections of Lolium spp. (26 populations), Trifolium spp. (19 populations) and other species (28 populations) were made by the GRS, Z team (Table 2). A diverse range of habitats was sampled covering a range of altitude, management systems and ecological conditions. Wild grassland was easily found but semi-natural grassland was uncommon in the collective farming landscape. Entry into a free-market economy is forcing changes on the collective farming system which dominates Czechoslovakian agriculture. Changes in crops and management practices will lead to a further reduction in the area of semi-natural grassland and genetic erosion of the unique forage grass and legume populations in Czechoslovakia. The collecting expedition took place in August 1992, 5 months before Czechoslovakia was divided into the separate states of the Czech Republic and Slovakia. In the text ‘Czechoslovakia’ is used to reflect the situation at the time of the collecting expedition. [ABSTRACT FROM AUTHOR]

Two sets of plants ( Lb and Lc), regenerated from different single-genotype-derived embryogenic suspension cultures of Lolium perenne cv Citadel, were evaluated for agronomic traits in a modified polycross design in the field. Seed from the primary regenerated plants was harvested to evaluate morphological and phenological traits of corresponding progenies in a replicated field experiment. When compared to seed-grown plants of the same cultivar, primary regenerants of the Lb set showed a significant delay in ear emergence and a more-erect growth habit, while primary regenerants from the Lc set showed a significantly higher seed yield. However, progenies of regenerated plants did not differ from those of seed-grown plants. Embryogenic suspension cells of L. perenne have the potential for producing fertile, well-performing, material which can be integrated into breeding programs. [ABSTRACT FROM AUTHOR]

An algorithm of automatic classification is proposed and applied to a large collection of perennial ryegrass wild populations from France. This method is based on an ascendant hierarchical clustering using the Euclidian distance from the principal components extracted from the variance-covariance matrix between 28 agronomic traits. A contiguity constraint is imposed: only those pairs of populations which are defined as contiguous are grouped together into a cluster. The definition of contiguity is based on a geostatistical parameter: the range of the variogramme, i.e. the largest distance above which the variance between pairs of population no longer increases. This method yields clusters that are generally more compact than those obtained without constraint. In most cases the contours of these clusters fit well with known ecogeographic regions, namely, for macroclimatic homogeneous conditions. This suggests that selective factors exert a major influence in the genetic differentiation of ryegrass populations for quantitatively inherited adaptive traits. It is proposed that such a method could provide useful genetic and ecogeographic bases for sampling a core collection in widespread wild species such as forage grasses. [ABSTRACT FROM AUTHOR]

Primary trisomics of perennial ryegrass, Lolium perenne L., were studied for meiotic behaviour, fertility, morphology and trisome transmission. Trisomics differed from each other in mean meiotic association, pollen fertility, seed set and morphology. The combined cytomorphological data suggested that the investigated trisomic plants included trisomes 2 to 7. No pollen transmission of trisomes was detected. Female transmission of trisomes ranged from 12% for tri 3 to 37% for tri 4 with a mean of 24% for the six trisomes. Trisome transmission was not related to either chromosome size or trivalent/univalent frequency, although the larger trisomes formed trivalents more frequently than the smaller trisomes. [ABSTRACT FROM AUTHOR]

The decomposition of perennial ryegrass straw was examined under mesophilic and thermophilic temperatures. Thermophilic conditions were used to define the composting process. The change in lipids, sugars, soluble polysaccharides, cellulose, and lignin was determined during a 45-day incubation. C, H, O, and N steadily decreased in both temperature treatments. The lignin content, as measured by the Klason or 72% HSO method, decreased by 10% under mesophilic and 29% under thermophilic conditions. The Klason lignin C loss was 25 and 39% under mesophilic and thermophilic incubations, respectively. The changes in element (C, N, H, and O) ratios indicated that 94% of the lignin fraction was altered during both low- and high-temperature incubations. The changes in the lignin-like fraction as shown by elemental ratios were more extensive than those indicated by the Klason method, showing that this lignin determination has limited value in describing plant residue decomposition. The decomposition of the straw components and the concomitant degradation of the lignin fraction represent an important decomposition process that facilitates the composting of ryegrass straw with a high C:N ratio. [ABSTRACT FROM AUTHOR]

Copper mine tailings pose many threats to the surrounding environment and human health, and thus, their remediation is fundamental. Coal spoil is the waste by-product of coal mining and characterized by low levels of metals, high content of organic matter, and many essential microelements. This study was designed to evaluate the role of coal spoil on heavy uptake and physiological responses of Lolium perenne L. grown in copper mine tailings amended with coal spoil at rates of 0, 0.5, 1, 5, 10, and 20%. The results showed that applying coal spoil to copper mine tailings decreased the diethylenetriaminepentaacetic acid (DTPA)-extractable Cd, Cu, Pb, and Zn contents in tailings and reduced those metal contents in both roots and shoots of the plant. However, application of coal spoil increased the DTPA-extractable Cr concentration in tailings and also increased Cr uptake and accumulation by Lolium perenne L. The statistical analysis of physiological parameters indicated that chlorophyll and carotenoid increased at the lower amendments of coal spoil followed by a decrease compared to their respective controls. Protein content was enhanced at all the coal spoil amendments. When treated with coal spoil, the activities of superoxide dismutases (SOD), peroxidase (POD), and catalase (CAT) responded differently. CAT activity was inhibited, but POD activity was increased with increasing amendment ratio of coal spoil. SOD activity increased up to 1% coal spoil followed by a decrease. Overall, the addition of coal spoil decreased the oxidative stress in Lolium perenne L., reflected by the reduction in malondialdehyde (MDA) contents in the plant. It is concluded that coal spoil has the potential to stabilize most metals studied in copper mine tailings and ameliorate the harmful effects in Lolium perenne L. through changing the physiological attributes of the plant grown in copper mine tailings. [ABSTRACT FROM AUTHOR]