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1.
Perennial grasses provide forage and environmental benefits in the agricultural systems of southern Australia, but persistent cultivars are lacking for the lower rainfall inland margins (<600 mm average annual rainfall). Potential new cultivars of cocksfoot (Dactylis glomerata L.), tall fescue (Festuca arundinacea Schreb. = syn. Lolium arundinaceum (Schreb.) Darbysh.) and phalaris (Phalaris aquatica L.) have been developed in response to this need. These and older cultivars were evaluated for persistence at five sites in south‐eastern Australia from 2009 to 2013. A wide range in rainfall was experienced, but survival was principally reduced by a severe spring–summer–autumn drought in the final year in which all species began to decline in persistence once the spring 2012 to autumn 2013 cumulative climatic moisture deficit became higher than about 700 mm and declined very severely at deficits over 1000 mm. The highly summer‐dormant cocksfoot ssp. hispanica control cultivar Kasbah showed outstanding survival of this event in the cropping zone of southern New South Wales, but not at the drier of two sites with acidic soils in central Victorian where all cocksfoot cultivars showed similar survival. Potential new summer‐active tall fescue cultivars survived well at the higher rainfall Victorian site and under high rainfall in northern NSW. All tall fescue cultivars experienced high mortality during a period of high moisture stress in the spring of the establishment year in southern NSW, but the Mediterranean cultivar Grasslands Flecha MaxP gradually recovered. Differences among phalaris cultivars were not large with new cultivars of North African origin being marginally more persistent at the drier site in southern NSW. Comparisons with results from the Mediterranean Basin are discussed. Although there was no clear evidence of differences in persistence between the new and old cultivars, some of the new cultivars were considered to show potential for commercial release.  相似文献   

2.
Perennial grass‐based pastures are uncommon in phased cropping rotations in south‐eastern Australia, where rainfall often limits production and persistence. The high reliance on pure legume‐based pastures limits overall pasture productivity and has adverse effects on environmental parameters such as weed incursion and ground cover. A field experiment was monitored over 5 years to examine the relative productivity of the temperate perennial grasses, phalaris (Phalaris aquatica) and cocksfoot (Dactylis glomerata) and determine whether contrasting seasonal activity enhances their persistence when grown in mixtures with lucerne (Medicago sativa) and annual legumes. Phalaris swards were shown to increase cumulative aboveground biomass by up to 96% and 32%, and in year 5 reduce annual grass emergence by between sevenfold and threefold compared to annual legume and lucerne/annual legume mixed swards, respectively. Only swards that included phalaris maintained ground cover above 70% in each autumn of the experimental period. Swards based on the highly summer dormant cocksfoot cultivar, Kasbah, were generally less productive over all, despite the cocksfoot showing a high level of persistence and good recovery following drought. Grass‐based swards that included lucerne were observed to produce ~35% greater legume biomass than a sward sown only to annual legumes. Cumulative legume biomass was greatest in lucerne swards in the absence of perennial grasses. The experiment was unable to demonstrate a consistent benefit in production and persistence associated with contrasting seasonal growth patterns. However, mixtures containing a range of functional types were consistently shown to enhance productivity over the duration of the experiment compared to less diverse swards. The potential to substantially increase forage productivity and ground cover, while reducing incursion by annual grass weeds, by including well‐adapted perennial grasses in mixtures with lucerne and annual legumes should be utilized.  相似文献   

3.
Increased recovery and recycling of manure phosphorus (P) by crops on dairy farms is needed to minimize environmental problems. The main objective of this study was to compare P utilization by orchardgrass (Dactylis glomerata L.) and tall fescue (Festuca arundinaceae Schreb.) from dairy manure or inorganic fertilizer. The study was conducted from 1994 to 2000 at the Cornell University Baker Farm, Willsboro, NY, on a somewhat poorly drained Kingsbury clay (very–fine, illitic, mesic Aeric Epiaqualfs). The design was a split‐plot in a randomized complete block with two manure rates (16 800 and 33 600 kg ha?1) and one nitrogen (N) fertilizer rate (84 kg N ha?1 at spring greenup and 56 kg N ha?1 prior to each regrowth harvest) as the main plots and grass species as subplots replicated six times. Fertilizer P [Ca(H2PO4)2] was applied to the fertilizer treatment in 1995 and 1996 at 11 kg P ha?1 year?1. Orchardgrass P removal averaged 21 % higher than tall fescue P removal for the spring harvest, but orchardgrass averaged 24 % lower P removal than tall fescue removal for all regrowth harvests from 1995–99. Phosphorus herbage concentration in the fertilizer treatment was in the range of 1.9–2.7 g P kg?1 compared with 2.2–5.3 g P kg?1 in the manure treatments. Seasonal P removal ranged from as low as 9.2 kg P ha?1 to as high as 48.5 kg P ha?1. Morgan extractable soil P in the top 0–0.20 m remained high through 1999, with 29.1 kg P ha?1 at the highest manure rate in tall fescue compared with 8.4 kg P ha?1 measured in 1993 prior to the experiment. In 2000, soil P at the highest manure rate in tall fescue dropped to 10.1 kg P ha?1, following cessation of manure application in 1998. Intensively managed harvested orchardgrass and tall fescue have the potential to remove large quantities of manure P.  相似文献   

4.
Development of tall fescue (Festuca arundinacea Schreb., 2n = 6x - 42) × Italian rye-grass (Lolium multiflorum Lam., 2n = 2 ×= 14) hybrids would enhance efforts to improve the quality of tall fescue. Two ‘Kentucky 31’ tall fescue בLemtal Italian ryegrass hybrids were obtained via embryo rescue on MS media containing casein hydrolysate, ascorbic acid and sucrose. Chromosome pairing at metaphase I had an average of more than 12 bivalents per cell. Since Festuca-Lolium pairing can account only for seven of the paired chromosomes, intergenomic as well as interspecific chromosome pairing is indicated. There was no cytoplasmic effect on chromosome pairing. To determine if enzymes could be used as genetic markers for distinguishing hybrids from self-contaminants in crosses, zymograms of PGI, 6-PGD, MDH, GOT and ACPH were obtained from parents and hybrids using starch gel etectrophoresis. PGI, 6-PGD and MDH had fewer bands in the diploid ryegrass, as compared with the hexaploid tall fescue and the tetraploid hybrid.  相似文献   

5.
Tall (Festuca arundmacea Schreb.) and hard (Festuca ovina var. longifolia (L.) Koch) fescues are widely sown to stabilize disturbed soils in the cool–humid and transition climatic zones of the USA. Our objectives were to: a) quantify changes in the allocation of dry matter and growth of tall and hard fescue, forced to grow on stored soil water in sandy soil; and b) compare dry matter allocation over time between roots and shoots to evaluate the dynamics of root-associated drought avoidance mechanisms. A randomized complete block experiment with four replications and two factors (species and stress level) was conducted in a greenhouse. The main blocks consisted of two fescue species: tall fescue and hard fescue; sub-blocks contained stress levels: well-watered and stressed. Low, medium and severe stresses were imposed by withholding water in one set of pots. The types of fescue species grown significantly affected leaf area (LA), plant height (PH), water use (WU), root length (RL), longest root (LR), root area (RA), shoot (SDB) and root dry biomass (RDB), and root:shoot ratio (R/S). Stress level affected PH, WU, LR and RL at low stress; WU, LR and RA at medium stress; LA, PH, SDB, WU, RL, LR, RA and R/S at severe stress. Tall fescue had greater LA, PH, WU, RA, RL, LR, SDB, RDB and R/S than hard fescue under all treatments. Stress reduced LA, PH, SDB, WU, RA, RL, LR and R/S. Significant correlations were obtained for LA with RL, WU, LR, PH. RA, SDB, RDB; RL with WU, LR, PH. RA, SDB. RDB; WU with LR, PH, RA, SDB, RDB; LR with PH. RA, SDB, RDB; PH with RA, SDB, RDB; RA with SDB, RDB; and SDB with RDB. In conclusion, hard fescue had a shallower root system, shorter plant canopy, slower growth, and transpired less water to make it more drought tolerant. Tall fescue, with a deeper root system, longer plant canopy, faster growth, and greater water transpiration, is less drought tolerant at medium and severe stresses. Root attributes strongly correlated with shoot attributes and can be considered for breeding programs promoting drought tolerance.  相似文献   

6.
Summer dormancy confers superior drought survival in cool-season perennial grasses and is likely to be of increasing importance as climate change proceeds although relatively little is known about this trait. This paper explores the relationship between the level of abscisic acid (ABA), the expression of summer dormancy and the onset and relief of water deficit in cool-season perennial grasses. Three cultivars of Dactylis glomerata L. (cocksfoot) known to differ in expression of summer dormancy were grown in the field over summer and in the glasshouse over winter under water deficit or full irrigation. Hydration and osmotic potentials of basal tissues were measured to assess the level of water deficit, and endogenous ABA was determined in the tissues by monoclonal immunoassay analysis. In a winter trial, higher contents of ABA were present when plant water deficits became greater so that there were no differences between the cultivars in the concentrations of ABA observed. In a summer trial a short period of waterlogging caused water status to increase in all cultivars, although in the maritime cultivar Oasis this was also associated with a rise in ABA contents. In contrast, in the summer-dormant cultivar Kasbah, only low ABA concentrations were observed throughout the entire period whether waterlogged or in drying soil. Heightened ABA levels are not induced by water deficit when summer dormancy is expressed in Dactylis glomerata. This contrasted with those cultivars unable to express summer dormancy where particularly in early summer severe water deficit was associated with heightened ABA levels.  相似文献   

7.
Molecular diversity and genetic affinity in the Lolium/Festuca grass complex have been assessed using simple sequence repeat (SSR) marker technology. The genotypic set was derived from three accessions of perennial ryegrass, two cultivars of Italian ryegrass, two cultivars of meadow fescue, two cultivars of tall fescue and 10 accessions from different intergeneric hybrid (Festulolium) combinations. The majority of the genomic DNA‐derived SSR primer pairs from perennial ryegrass (LPSSR) and Italian ryegrass (LMSSR) produced clear, simple and distinctive amplification products from the majority of the genotypes. The efficiency of cross‐specific amplification for LPSSR markers varied from 38% in meadow fescue to 93% in two cultivars of Festulolium and from 57% in meadow fescue to 87% in Italian ryegrass for LMSSR markers. Of 40 amplified markers, 14 (35%) produced species‐difference alleles in the relation to cultivars used in the present study. Thirty‐five LPSSR locus‐derived alleles were found to be specific to Lolium species, four to meadow fescue and six to tall fescue. For LMSSR alleles, eight were specific to Lolium species and five were only associated with Italian ryegrass, and null alleles were detected for meadow fescue in all instances. These species‐difference markers could clearly identify different accessions of Festulolium. Cluster analysis separated the individual taxa and showed grouping of intergeneric hybrids based on genomic composition. The data distinguished between the species and reflected the known pedigree of the cultivars and the differences between the species. The dendrogram also distinguished between the Festulolium accessions and clearly demonstrated the relations between Festulolium hybrids and their parent species.  相似文献   

8.
There is a large hectarage of tall fescue in Alabama. Recognition of the deleterious effects of the endophytic fungus Acremonium coenophialum has resulted in substantial acceptance of new endophyte-free cultivars. Destruction of old pastures and the concomitant loss of potentially valuable adapted germplasm could be a valid cause for concern. The objectives of this study were to evaluate genetic variation for maturity and plant morphological traits, both among and within tall fescue cv. ‘Kentucky 31’ populations from 18 to 38 year-old pastures in Alabama. Ten populations of approximately 50 plants each were collected from old Alabama tall fescue pastures. Two pastures were sampled in each of five counties, representing the five major land use areas of the state. In 1990, spaced plants of all populations were evaluated at heading time for maturity, morphological, and disease traits at two locations in central Alabama. Endophyte infection level of the populations ranged from 2 to 100 %. Maturity was highly correlated with tiller length and flag leaf width and was used as a covariate for these traits in the analysis of variance. Leaf rust and net blotch ratings were negatively correlated. Significant variation among populations was observed for maturity and flag leaf dimensions, most variation being due to differences among source counties. Significant variation was observed within all populations for maturity and morphological traits, but only in seven populations for leaf rust. No within-population variation was detected for net blotch. The average precipitation for the month of May explained 81 % of the variation among populations for maturity. Age of the pasture sampled had a significant effect on tiller diameter (r2= 0.55), and latitude of the pasture sampled was the best individual predictor of leaf width (r2= 0.42). This study reveals that considerable genetic diversity, largely influenced by climatic conditions, exists among ‘Kentucky 31’ tall fescue ecotypes from Alabama.  相似文献   

9.
Summary Forty-eight accessions of tall fescue (Festuca arundinacea Schreb.), collected from Northern to Southern Italy, were analyzed using both univariate and multivariate analysis applied to a set of 12 quantitative traits. Four principal components were found to explain 77% of the total variation in the dependence structure. Productivity characters together with heading time and dimensions of flag leaf appeared to be the major sources of diversity among tall fescue populations. On the basis of the 4 principal components similar populations were clustered according to minimal distance analysis. Seven clusters were identified. The results of cluster analysis confirmed the presence of a remarkable diversity within the germplasm collection and explained why results of a univariate analysis of variance did not reveal significant differences among groups of accessions collected in Northern, Central and Southern Italy. The multivariate approach seemed to point out a problem of genetic erosion of the local germplasm in the Po Valley (Northern Italy) and, on the whole, appeared to be a valid system for tall fescue germplasm evaluation.Research supported by C.N.R., Italy, special grant I.P.R.A., Subject 1.5.1., paper n. 1146.  相似文献   

10.
P. A. York  R. Cook 《Euphytica》1989,43(1-2):135-141
Summary Reactions of 13 grasses to Meloidogyne naasi varied with species; ryegrasses, fescues and their hybrids were generally susceptible and cocksfoot and timothy resistant. Marked variation in host resistance levels occurred between genotypes within cultivars.Selection of single plants, followed by tests on replicate tillers, identified resistant and susceptible genotypes in both Italian and perennial ryegrass cultivars. Resistant plants had few nematode-induced galls and fewer females and eggs than susceptibles. There was more or less continuous variation, with many genotypes intermediate between extremes of resistance and susceptibility. Selected resistant and susceptible genotypes are of use in assessing variation in nematode populations and as controls for breeding and selection programmes.  相似文献   

11.
Soil salinity is a notorious abiotic stress which constrains plant growth and limits crop productivity. Recent advances in phytogenetics especially the discovery of marker-trait association have facilitated the efficient selection of stress-tolerant crops. The objective of this study was to evaluate tall fescue (Festuca arundinacea Schreb.) accessions growing under salt stress in order to identify salt-tolerant and salt-sensitive genotypes using physiological and molecular markers. The population consisted of 114 diverse tall fescue accessions which were assessed using 99 simple sequence repeat (SSR) markers and five functional physiological traits i.e., turf quality, leaf water content, chlorophyll content, relative growth rate, and evapotranspiration rate. Salinity stress induced great variations among the functional physiological traits and there were significant correlations among them. The population structure analysis revealed two distinct populations, while association mapping between the SSRs and phenotypic traits identified significant associations. In addition, the accessions that maintained relatively higher physiological traits had a significantly lower accumulation of Na+ and Cl? in the roots compared to those whose functional traits declined. We identified six most salt-tolerant accessions due to their high values of physiological parameters and significantly low accumulation of Na+ and Cl? in the roots. Similarly, we identified six accessions we considered to be most salt-sensitive as observed by high Na+ and Cl? accumulation plus a decline in the physiological activities. Our findings are helpful to tall fescue breeders with a goal of producing tall fescue cultivars with enhanced salt tolerance.  相似文献   

12.
The variation of the water-soluble carbohydrate (WSC) concentration in foliage and stubble and winter hardiness among cocksfoot (Dactylis glomerata L.) ecotypes originated from diverse countries were studied in the field in order to find a breeding material for the improvement of WSC. The total WSC concentration of foliage was found to be highest in Japanese cultivars and lowest in ecotypes from northern Europe in summer and autumn. The variation of fructan concentration in stubble among ecotypes was larger than the variation of mono and disaccharide concentrations in stubble and that of total WSC concentration in foliage in both winters over which this study was conducted. The total WSC and fructan concentrations in the stubble of ecotypes from Spain and southern Europe, derived from the Mediterranean region, were highest in summer. Ecotypes from Japan showed the highest concentration of total WSC in stubble, and were especially high in fructan concentration in autumn. Ecotypes from France, central Europe and central Asia, like Japanese cultivars, also showed a high fructan concentration. The latitude of origin was negatively correlated with WSC concentration and plant vigor in autumn. The altitude of origin was negatively correlated with plant vigor in autumn and positively correlated with fructan concentration in stubble, winter hardiness and snow endurance. Typhula snow blight resistance was related with the amount of the increase in fructan in the plants and with their growth habits in autumn. The fructan concentration of foliage and stubble in autumn was found to be closely related with winter hardiness in cocksfoot ecotypes. A breeding material which has a high WSC concentration in the foliage could not be found among the ecotypes in this study. However, some ecotypes that showed disease resistance, good winter hardiness and plant vigor would be useful as breeding materials for Hokkaido.  相似文献   

13.
Two main types of summer dormancy in tall fescue [Schedonorus arundinaceus (Schreb.) Dumort] are recognized, eco-dormancy and endo-dormancy. Endo-dormancy is a physiological response to environmental signals leading to slowing of metabolic activity in meristematic tissues and most likely controlled by circadian clock genes. Therefore, it is genetically inherited and allelic variation among and between summer-dormant and non-dormant varieties is expected. The main objective of this study was to explore the association between dormancy and various candidate genes. Twenty-three genes were amplified and sequenced in two dormant and two non-dormant checks. Nucleotide variants unique to each group were converted to kompetitive allele specific PCR markers and were tested on 52 dormant and non-dormant accessions. Five markers, from the genes CONSTANS and TERMINAL FLOWER showed significant associations (R2 = 0.10 to 0.13, p < 0.05) with field phenotypic scores. These two genes are known to modulate meristem determinacy and growth, suggesting that meristem determinacy is probably one of the mechanisms involved in summer dormancy in tall fescue. Another five markers showed significant associations with the surrogate germination phenotype (R2 = 0.13 to 0.20, p < 0.05). One marker originated from dormancy-associated MADS-box gene sequence, three markers originated from auxin response factors sequences, and one marker was derived from heat shock proteins sequences. These results confirm the implication of photoperiod and temperature in the regulation of summer dormancy. A selection index combining these markers may be valuable for the differentiation between dormant and non-dormant tall fescue genotypes.  相似文献   

14.
This paper reports on the first results of feeding value experiments, assessed with sheep, of hybrids between tetraploid Italian ryegrass (Lolium multiflorum, 2n = 4×= 28) and a progenitor of tall fescue, Festuca arundinacea var. glaucescens (2n = 4×= 28). Three hybrid populations resulting from either high, low or no selection for palatability were compared with a variety of Italian ryegrass as control and two varieties of the cultivated hexaploid (2n = 6×= 42) tall fescue, one of which had been selected for high palatability. On average, the hybrid populations were found to be as palatable as the improved tall fescue with voluntary intake (VI), in vivo digestibility of organic matter (DOM), and net energy expressed in fodder units for milk, similar to the best palatable tall fescue and to Italian ryegrass. However, selection for improved palatability among hybrids did not result in any further improvement of other traits, except VI in the hybrid selected for high palatability which significantly exceeded VI of Italian ryegrass. In conclusion, intergeneric hybridization between L. multiflorum and F. arundinacea var. glaucescens led to an immediate increase of feeding value compared with selection for palatability in tall fescue. However, to improve feeding value of hybrids further, similar selection for high palatability appeared questionable and possibly detrimental for other agronomic traits because of complicated inheritance in tetraploid L. multiflorum×F. glaucescens hybrids.  相似文献   

15.
High fertilizer prices and improved environmental stewardship have increased interest in grass-legume mixed pastures. It has been hypothesized, but not validated, that the ecological combining ability between grasses and legumes can be improved by breeding specifically for mixture performance. This experiment examined the predicted efficiency of selection in a grass monoculture environment to indirectly improve tall fescue (Lolium arundinaceum (Schreb.) Darbysh.) forage mass in a grass-legume mixture. Heritability, genetic and rank correlations, and selection efficiencies were estimated for forage mass in a tall fescue half-sib population grown as spaced-plants overseeded with either turf-type tall fescue (monoculture) or alfalfa (mixture). Heritability for tall fescue forage mass in monoculture ranged from 0.32 to 0.70 and were always similar or greater than those in mixture (range 0.27–0.55) for four successive harvests and annual total. Genetic correlations between monoculture and mixture tall fescue forage mass varied with values of 0.48, 0.92, ?0.31, 0.70, and 0.25 in June, July, August, October, and annual total, respectively. Indirect selection efficiencies exceeded or approached direct selection for mixtures only in July and October (1.29, and 0.73, respectively). Whereas, indirect selection efficiencies were low in June, August, and annual forage mass (0.58, ?0.31, and 0.28, respectively). Moreover, low Spearman’s rank correlations (?0.03 to 0.35) indicated differing half-sib family performance between the monoculture and mixture environments. Results indicate that direct selection should be used to improve tall fescue forage mass in a grass-legume mixture, and support the hypothesis of increasing ecological combining ability by breeding for mixtures per se.  相似文献   

16.
Efficient crop growth with low nitrogen (N) application is becoming a requirement to face the concern on excessive N emission to the environment and the increasing cost of fertilizers. This study compared six natural populations and three improved varieties of tall fescue (Festuca arundinacea Schreb.) for dry‐matter yield over 4 years under ordinary N fertilization (450 kg ha?1 in the 4 years) and very low N fertilization (only 40 kg ha?1 prior to sowing). Both endophyte‐infected (EI) and endophyte‐free (EF) forms of each accession were sown. On average, ordinary fertilization implied 30 % higher yield than very low fertilization and the EI germplasm outyielded the corresponding EF germplasm (+4.4 %). Mean yield of improved varieties was higher than that of natural populations under ordinary fertilization (P < 0.05), whereas the two germplasm groups did not differ under very low fertilization. Accession × N fertilization interaction was found among natural populations but not among varieties (P < 0.05). A few natural populations were top‐yielding under very low fertilization and may be exploited, possibly in combination with endophyte infection, to select tall fescue varieties with enhanced performance under limited N application.  相似文献   

17.
Selection of main cool‐season turfgrasses (perennial ryegrass and red fescue) for resistance to red thread disease caused by Laetisaria fuciformis has not progressed during the last 30 years because of low reproducibility of experiments carried out under natural infection. In this study, evaluation of a set of the turfgrass cultivars, including non‐host fodder grasses as control, was performed in a climatic chamber, a cold house and in the field using three types of artificial inoculum, and correlations between trials were analysed. In general, cultivars of Festuca rubra were more susceptible to the disease but differentiated better than cultivars of Lolium perenne. Significant interactions between cultivars of L. perenne and F. rubra and isolates of L. fuciformis were found. The fungus was also able to colonize leaves of sow thistle and wheat seedlings. In field conditions and in the glass cold‐house Dactylis glomerata was found to be relatively resistant to red thread disease. A possible selection programme is proposed.  相似文献   

18.
Extensive livestock is a basic socio‐economic feature of the Mediterranean region whose environmental and economic sustainability depends on the ability of forage resources to withstand climatically stressful conditions. Perennial forages such as tall fescue can be a valuable alternative to annuals, if they can survive across successive summer droughts. Three‐year dry matter yield and plant survival of five cultivars of Mediterranean‐type tall fescue were evaluated in six sites of Algeria, France, Italy, Morocco and Portugal, with the following objectives: (i) modelling adaptive responses and targeting cultivars as a function of environmental factors associated with genotype × location interaction; and (ii) defining plant ideotypes, adaptation strategies and opportunities for international co‐operation for regional breeding programmes. Site mean yield and winter temperatures were positively correlated, whereas sward persistence was positively correlated to lower site heat and drought stress. Cultivar adaptation was adequately modelled by factorial regression as a function of site spring–summer (April–September) drought stress (long‐term potential evapotranspiration minus actual water available) for yield, and annual drought stress for final persistence. Specific‐adaptation responses to high‐ or low‐stress environments emerged which were consistent with drought‐stress levels of cultivar selection environments. However, the wide‐adaptation response of cultivar Flecha suggested that breeding for wide adaptation can be feasible.  相似文献   

19.
The meiotic behavior of three tall fescue (Festuca arundinacea, 2n = 6x = 42) genotypes, giant fescue (F. gigantea, 2n = 6x = 42), and their reciprocal F1 hybrids and C1, amphiploids was evaluated to determine the parental genomic relationships. Isozyme banding patterns were used to confirm the parental identity of the hybrids and amphiploids. At meta-phase I, the parents had predominantly bivalent pairing. The hybrids had an average of 9.51 I, 16.02 II, 0.12 III, 0.02 IV, and the amphiploids had 2.17 I, 38.82 II, 0.60 III, 0.58 IV, 0.01 V—VIII. The prevalence of bivalent pairing in both hybrids and amphiploids suggested a homoeologous relationship between the six genomes, with four of the six being more closely related. Bivalent pairing in the amphiploids indicated genetic regulation of chromosome pairing. Zymograms were obtained for acid phosphatase (ACPH), alcohol dehydrogenase (ADH), glutamate oxaloacetate transaminase (GOT), malate dehydrogenase (MDH), 6-phosphogluconate dehydrogenase (6-PGD) and phosphoglucoisomerase (PGI). The three tall fescue and giant fescue parents had different zymograms for ACPH, MDH, 6-PGD and PGI; thus, the tall fescue parents of the hybrids and amphiploids could be determined based on the banding patterns of these four enzymes. Phenotypes were determined for ACPH-1, PGI-2 and 6-PGD-1. ACPH-1 may be used to follow the introgression of giant fescue chromatin into a certain tall fescue genotype.  相似文献   

20.
Summary Intergeneric symmetric and asymmetric somatic hybrids have been obtained by fusion of metabolically inactivated protoplasts from embryogenic suspension cultures of tall fescue (Festuca arundinacea Schreb.) and unirradiated or 10–500 Gy-irradiated protoplasts from non-morphogenic cell suspensions of Italian ryegrass (Lolium multiflorum Lam.). Genotypically and phenotypically different somatic hybrid Festulolium mature flowering plants were regenerated.Species-specific sequences from F. arundinacea and L. multiflorum being dispersed and evenly-represented in the corresponding genomes were isolated and used for the molecular characterization of the nuclear make-up of the intergeneric, somatic Festulolium plants recovered. The irradiation of Italian ryegrass protoplasts with 250 Gy X-rays prior to fusogenic treatment favoured the unidirectional elimination of most or part of the donor chromosomes. Irradiation of L. multiflorum protoplasts with 500 Gy produced highly asymmetric (over 80% donor genome elimination) nuclear hybrids and clones showing a complete loss of donor chromosomes.The RFLP analysis of the organellar composition in symmetric and asymmetric tall fescue (+) Italian ryegrass regenerants confirmed their somatic hybrid character and revealed a bias towards recipient-type organelles when extensive donor nuclear genome elimination had occurred.Approaches aimed at improving persistence of ryegrasses based on asymmetric somatic hybridization with largely sexually-incompatible grass species (F. rubra and Alopecurus pratensis), and at transferring the cytoplasmic male sterility trait by intra- and inter-specific hybridization in L. multiflorum and L. perenne, have been undertaken.Abbreviations cpDNA chloroplast DNA - CMS cytoplasmic male sterility - 2,4-D 2,4-dichlorophenoxy-acetic acid - IOA iodoacetamide - mtDNA mitochondrial DNA - RFLP restriction fragment length polymorphism  相似文献   

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