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1.
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   

2.
Two medium leaf size varieties of white clover (Trifolium repens L.) were grown in mixture with a range of grass species and varieties in a field experiment conducted over 4 years. The clovers were grown singly or as a blend in swards with a tetraploid perennial ryegrass (Lolium perenne L.), a diploid Italian ryegrass (Lolium multiflorum L.) or tetraploid hybrids between these two species (Lolium x boucheanum Kunth). These grasses were also grown in monoculture. Swards were managed in a regime involving two periods of sheep grazing, two periods of cattle grazing and a silage cut in the same year for 4 years. The objectives of this experiment were 3‐fold: (1) to examine the yield and persistency of white clover in highly productive systems with modern perennial, hybrid and Italian ryegrasses; (2) to compare the performance of white clover varieties grown singly in mixture with grasses with their performance together as a blend, and (3) to examine the persistency of new Italian ryegrass varieties, exemplified by AberComo. The clover content of the sward remained high throughout the experiment, with a mean of 31 % overall. Differences in clover yield between plots were largely attributable to the effects of companion grasses. Total yields were very similar in plots containing different clover varieties and in plots where these varieties had been grown singly or as a blend. Grass yields in mixture were greater than those in monoculture but showed similar relative rankings. The diploid Italian ryegrass variety AberComo showed an unexpectedly high yield in the 4th year of the experiment. The implications of these results for strategies for productive, sustainable agriculture using modern white clover and ryegrass varieties are discussed.  相似文献   

3.
Genetic polymorphism within and between three species of forage grasses, perennial ryegrass (Lolium perenne L), meadow fescue (Festuca pratensis Huds.) and tall fescue (Festuca arundinacea Schreb.), was analyzed using restriction fragment length polymorphism (RFLP) markers detected by rice cDNA probes developed at the Rice Genome Research Programme of Japan (RGP). One hundred and ninety‐seven rice cDNA clones were used for hybridization to genomic DNA of forage grasses. Many of the rice cDNA clones produced no visible band or only a smear with no discrete bands. Twenty‐three clones showed high efficiency cross‐hybridization to the genomic DNA of forage grasses. Genetic variation was evaluated for five varieties and one population of forage grasses using 12 polymorphic rice cDNA RFLP probes. Genetic variability within varieties as measured by Rogers’ genetic distance was considerably lower for the F. pratensis variety ‘Tomosakae’ than for the L. perenne and F. arundinacea varieties. To determine the genetic diversity between varieties of different species, cluster analysis was performed using data from the 12 RFLP probes. The two accessions of Lolium perenne were clustered more closely together than the three varieties of F. arundinacea. Two Japanese varieties of F. arundinacea were grouped in the same cluster. The variety‐specific RFLP markers were seen among six accessions of L. perenne, F. pratensis and F. arundinacea. Such variety‐specific RFLP markers would provide very useful tools for breeding programmes such as the intergeneric hybridization of Lolium and Festuca genera.  相似文献   

4.
Microsatellite or simple sequence repeat (SSR) markers are valuable tools for many purposes, such as phylogenetic, fingerprinting and molecular breeding studies. However, such marker resources are unavailable in Assam tea (Camellia assamica ssp. assamica; Masters). With an objective to enrich the repertoire of microsatellite markers in traditional tea, 185 novel microsatellite (150 genomic and 35 genic) markers were identified from (GA)n‐enriched genomic libraries and public expressed sequence data in Assam tea. High‐quality 0.412‐Mb non‐redundant (NR) genomic data set derived from nucleotide sequencing of 1297 (GA)n‐enriched genomic positive clones and 2723 unigenes (1.33 Mb) predicted from 10 803 random public expressed sequence tags (ESTs) in C. assamica ssp. assamica were utilized for identification of genomic and genic microsatellite markers, respectively. The average number of alleles and polymorphic information content (PIC) recorded for the newly developed SSR markers were 6.17 and 0.398, respectively. The average observed (Ho) and expected (He) heterozygosity varied from 0.626 to 0.697, respectively. These markers were found to be highly transferable (74.5–100%) to cultivated (C. sinensis, C. assamica ssp. lasiocalyx) and five wild Camellia species. Genetic diversity coefficient detected a high level of divergence in 24 cultivated tea accessions (69.3%). Phylogenetic analysis revealed that major groupings were broadly in accordance with taxonomic classification of tea, and all the wild Camellia species remained as an out‐group. The high polymorphic content coupled with high rate of cross‐transferability demonstrates wider applicability of novel microsatellite markers in genotyping, genetic diversity, genome mapping and evolutionary studies in various Camellia species.  相似文献   

5.
The potential for introgression of Festuca glaucescens into tetraploid ryegrass Lolium multiflorum was assessed using a simplex homeoallele at the phosphoglucoisomerase isoenzyme locus (Pgi-2). Overall, the F. glaucescens species-specific marker was found to be transmitted into Italian ryegrass at a rate close to 0.5 suggesting a high rate of homeologous pairing in BC1 and of intergeneric recombination in BC2. Significant variations in transmission rate among progenies in advanced generations indicated that recombination could result from various chromosome rearrangements possibly involving more than one fescue chromosome with some selection against duplex-like introgressed genotypes. Hence, introgressing F. glaucescens genes into tetraploid ryegrass appeared as further procedure to exploit versatility in fescue species, mostly restricted so far to introgression from F.arundinacea or F. pratensis into diploid ryegrass. Implications in terms of breeding strategy and marker-assisted selection are briefly discussed in respect to the genetic control of traits of interest to be introgressed. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

6.
Perennial ryegrass (Lolium perenne L.) is the most important temperate forage grass species. Unfortunately, the nutritional value of perennial ryegrass declines as maturity progresses, mainly because of a high concentration of poorly digestible compounds in inflorescences. Therefore, the development of forage‐type ryegrass varieties with extended vegetative growth is of interest for agriculture. To delay floral transition in perennial ryegrass the Arabidopsis ATH1 gene driven by the maize ubiquitin promoter, the rice actin promoter or the rice OSH1 promoter, respectively was introduced. In ATH1‐expressing plants heading was delayed, and in a number of cases the plants never flowered at all. Such non‐ or late‐heading was accompanied by the outgrowth of normally quiescent lateral meristems into extra leaves, resulting in a leafy growth habit. When eventually heading, these plants generally produced a reduced number of inflorescences. These observations suggest that ATH1‐mediated delay of heading may be useful to improve fodder quality of perennial ryegrass.  相似文献   

7.
Meadow fescue (Festuca pratensis), Italian ryegrass (Lolium multiflorum), their hybrid Festulolium braunii and perennial ryegrass (Lolium perenne) were grown hydroponically under vegetative (20 °C) and hardening (8 °C, 0 °C) regimes. The relative shoot/root growth ratio K, linear root growth rate and other parameters were estimated. When the temperature was lowered from 20 °C to 8 °C, the relative shoot/root growth ratio K of F. pratensis decreased to 0.6, i.e. much more than that of Lolium, suggesting that at 8 °C F. pratensis shoot growth blockage occurs. Further, by dropping the temperature from 8 °C down to 0 °C, the K ratio of F. pratensis increased significantly, while the linear root growth rate decreased much more markedly than in the other species – it suggests also a blockage of root growth. This growth slowdown of stress‐tolerant F. pratensis shoots and at a lower temperature also of its roots is inadequate to the direct impact of temperature and, thus, indicates a two‐step qualitative reorganization, i.e. transition into a qualitatively new state of stress. This phenomenon does not manifest itself in the less stress‐tolerant Lolium and Festulolium species but is expressed in stress‐tolerators, allowing them to achieve their strategic goal – to survive under extreme conditions.  相似文献   

8.
Bulb onion (Allium cepa L.) is an ancient crop that is thought to have originated in Central Asia and has been cultivated for over 5000 years. Classical genetic and plant breeding approaches have been used to improve onion yield, quality, and resistance against biotic and abiotic stresses. However, its biennial life cycle, cross‐pollinated nature and high inbreeding depression have proved challenging for the characterization and breeding of improved traits. New technologies, notably next‐generation sequencing, are providing researchers with the genomic resources and approaches to overcome these challenges. Using these genomic technologies, molecular markers are being rapidly developed and utilized for germplasm analysis and mapping in onion. These new tools and knowledge are allowing the integration of molecular and conventional breeding to speed up onion improvement programmes. In this review, we outline recent progress in onion genomics and molecular genetics and prospects for enhancing onion yield and quality in the future.  相似文献   

9.
Four grass species typically found in semi-natural pastures in the UK were sown individually in boxes (85 × 44 × 14 cm) to create micro-swards. Yorkshire fog (Holcus lanatus L.); creeping bent (Agrostis stolonifera L. cv Kromi); rough meadow-grass (Poa trivialis L.); and perennial ryegrass (Lolium perenne L. cv Glen) were offered to yearling Simmental × Holstein steers in short-term tests to characterize bite mass in relation to morphological traits of the grass species. Boxes were weighed (±0.1 g) before and after a 5 min period during which the steers were allowed to take ~50 bites. Perennial ryegrass had the greatest sward surface height (17.7 cm vs. mean 12.7 cm for the other species). Extended tiller length was greatest for ryegrass (17.3 cm) and least for rough meadow-grass (13.5 cm). Leaf length was greatest for ryegrass (6.5 cm) and Yorkshire fog (7.0 cm) and least for creeping bent (4.0 cm). Sward DM% was lowest for ryegrass (19.7%) and highest for creeping bent and rough meadow-grass (mean 23.2%). Number of bites taken from the boxes did not differ between grass species (mean 32.7 bites). Mean dry matter bite mass was greatest for perennial ryegrass (0.50 vs. mean 0.37 g DM bite−1 for the other species). Regression analyses indicated that the best sward variables for predicting mean DM bite mass were sward DM% (F prob. = 0.066) and sward surface height (F prob. = 0.086). While morphological characteristics affected bite mass, more is yet to be learned about other factors that may affect intake characteristics of forage species to improve economic and environmental sustainability.  相似文献   

10.
Five candidate genes LpIAA1, LpRUB1, LpBRI1, LpSHOOT1 and LpTB1 with putative function in plant architecture were allele sequenced in a panel of 96 diploid perennial ryegrass genotypes of diverse origin. The total length of the non‐redundant genomic DNA alignment was 5425 bp and revealed 270 polymorphic sites in total. A negative significant Tajima's D value was detected in LpTB1 gene, suggesting selection pressure for low‐frequency alleles in this gene. All 96 genotypes were evaluated for plant height and dry matter yield over two years. Marker–trait associations were calculated between polymorphic sites and both phenotypic traits. Three indels and three single nucleotide substitutions in LpTB1 gene were significantly (P < 0.05, q < 0.05) associated with plant height, while one indel was associated with dry matter yield. The results suggest putative role of LpTB1 gene in plant height determination in perennial ryegrass and provide means for target allele selection.  相似文献   

11.
多年生黑麦草(Lolium perenne L.)是一种重要的栽培牧草,具有多年生、植株繁茂、叶多质嫩、可消化物质产量高等特征,适宜用作饲草及草坪草,具有经济价值和生态效益。本综述总结概括了多年生黑麦草分子标记的开发与应用进展,重点介绍分子标记在多年生黑麦草遗传多样性分析、遗传连锁图谱构建、QTL定位分析中的应用情况,并简述了多年生黑麦草基因组研究进展。旨在为进一步发掘多年生黑麦草基因组结构和功能特点,选育优良黑麦草品种提供理论依据。  相似文献   

12.
Amplified fragment length polymorphism (AFLP) analysis has been used to measure genetic diversity in perennial ryegrass (Lolium perenne L.) and to relate intra- and interpopulation variation to breeding history. Cluster analysis of AFLP data from contrasting populations showed features consistent with the origins of these varieties. Significant differences in intrapopulation diversity were detected and partial separation of different cultivars was observed. Restricted base cultivars, derived from small numbers of foundation clones, were suitable for this type of study, allowing near complete discrimination of closely related cultivars. Analysis of bulked samples was based on the pooling of genomic DNA from 20 individuals from 6 selected populations. Cluster analysis of AFLP data from bulked samples produced a phenogram showing relationships consistent with the results of individual analysis. AFLP profiling provides an important tool for the detection and quantification of genetic variation in perennial ryegrass. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

13.
C. Oertel  F. Matzk 《Plant Breeding》1999,118(6):491-496
Crown rust, Puccinia coronata Corda, causes one of the most damaging foliar diseases in Italian ryegrass, Lolium multiflorum Lam. For introgression of crown rust resistance, highly resistant hybrids of the crosses Festuca arundinacea (2n = 6x = 42) ×L. multiflorum (2n = 4x = 28) and reciprocally, L. multiflorum (2n = 2x = 14) ×Festuca pratensis (2n = 4x = 28) and subsequently resistant recombinant individuals were used as female parents and susceptible cultivars of Italian ryegrass as male parents in three successive backcrosses. The BC3 plants were selfed and crossed mutually. Uredospores of seven different crown rust isolates collected from plants of L. multiflorum, Lolium perenne, F. pratensis, F. arundinacea and L. multiflorum × F. pratensis hybrids were applied to identify the resistance or susceptibility of the parental species, backcrossed, selfed and intercrossed progenies. The various crown rust populations revealed a species-specific capability to infect plants of the Lolium-Festuca complex corresponding to the host species from which the spores originated. Selected BC9 plants, however, were found to be completely resistant to all crown rust populations tested. Successful introgression of the resistance was achieved from F. arundinacea as well as from F. pratensis. The resistance represents a dominant character, apparently based on a strong heterologous incompatibility between host and pathogen. In phenotype, bivalent formation during meiosis and in fertility, the novel germplasms are comparable with the L. multiflorum cultivars.  相似文献   

14.
Perennial ryegrass (Lolium perenne L.) is the most important grass species for temperate grassland agriculture. The genetic relationship and distance among cultivars is largely unknown but of great interest for breeding programmes. The objectives of this study were to (i) investigate the molecular variation and structure of population cultivars, (ii) describe the relationship among cultivars in terms of the modified Rogers’ distance, and (iii) determine the minimum sample size required for characterization of cultivars of L. perenne using random amplified polymorphic DNA (RAPD) markers. A total of 22 ryegrass cultivars, mainly of European origin, were investigated with RAPD markers. The minimum sample size required for the characterization of cultivars was about 20 individuals per population. An analysis of molecular variance (AMOVA) revealed a much larger genetic variation within cultivars (66%) than between them (34%).  相似文献   

15.
The self-fertility of chromosome-doubled haploid lines of perennial ryegrass and their first (I1) and second (I2) generation selfed offspring was studied. The overall seed set was low, 0—0.4 seeds per spike, as would be expected for chromosome-doubled haploids of a self-incompatible species. Nevertheless, significant genetic variation was observed for self-fertility within three of the six lines studied. Within one line, three I2-clones showed increased self-fertility, while in two other lines one and three I1-clones, respectively, showed significantly increased self-fertility. Selection, during selfing, of rare pollen grains with mutations in the self-incompatibility system could explain the observed changes and would lead to a general breakdown of self-incompatibility in Lolium perenne during repeated selfing of chromosome-doubled haploids.  相似文献   

16.
Lolium perenne L. (perennial ryegrass) is the principle forage grass species in temperate agriculture. Improving biomass yield still remains one of the most important aims of current forage breeding programmes. A quantitative trait locus (QTL) study investigating biomass yield traits in perennial ryegrass was carried out in greenhouse and field environments. The study is based on an F2 population consisting of 360 individuals derived from two inbred grandparents where the F1 has a large biomass yield phenotype. For both experimental environments co-localized QTL for biomass yield traits including fresh and dry weight and dry matter were identified on linkage groups 2, 3 and 7. A major QTL for fresh and dry weight was identified on LG 3 which explained around 30% of the phenotypic variance in the field experiment. The findings of this study are discussed with regard for their potential in research and breeding.  相似文献   

17.
Pilar Hernandez 《Euphytica》2005,146(1-2):95-100
Summary There is an increasing amount of public sequence information for the main cultivated cereals, such as wheat and barley. It is not foreseeable that comparable efforts or resources could be devoted to related wild species. However, wild species are interesting sources of genetic variation through introgression breeding. Comparative genomics can be a helpful approach to make use of the available genomic resources. In this context, the potential of the wild barley species Hordeum chilense has been explored in recent years. It exhibits great levels of polymorphism and high crossability with different cereal genera. In addition, interesting biotic and abiotic stress resistance genes, and important quality traits like carotene content and seed storage protein variability shown in the species are also expressed in wheat backgrounds, and are the basis of a breeding program. Different approaches have been undertaken for tagging H. chilense genomic regions in a wheat background. The search for the most suitable DNA marker system started with the development of RAPD and SCAR markers due to a lack of sequence information from the wild species. Transferability of markers from wheat and barley (like STSs or SSRs) have also been useful approximations. More recently, SNP development is being accomplished for the species. In this work, the situation and prospects with the available molecular tools are considered from a practical point of view.  相似文献   

18.
The expected temperature rise in late summer/early autumn can change the conditions for acclimation and affect the winter survival of perennial crops. This study examined the effect of the temperature just before the onset of cold acclimation (pre‐acclimation) on freezing tolerance of timothy (Phleum pratense L.), perennial ryegrass (Lolium perenne L.) and red clover (Trifolium pratense L.) populations (both cultivars and breeding populations) adapted to either northern or southern parts of Norway. Using phytotron experiments, we studied whether increasing pre‐acclimation temperature delays growth cessation, affects photoacclimation and reduces freezing tolerance. Furthermore, we assessed whether these effects were related to the latitudinal adaptation of the plant material. The results showed that a rise in pre‐acclimation temperature decreased both cold acclimation capacity and photoacclimation in these species. This affected the freezing tolerance, which was reduced significantly more in northern‐adapted population of timothy and perennial ryegrass compared with southern‐adapted populations. Red clover was less affected by temperature changes than the grasses.  相似文献   

19.
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20.
An improved method is reported for polyploid induction in Lolium (ryegrass), and in sterile F1 hybrids between Lolium and Festuca (fescue). Two factors greatly increased the survival rate of colchicine‐treated embryos of Lolium perenne (perennial ryegrass) germinated and cultured in vitro (1) a high concentration of sucrose (100 g/1) in the germination medium and (1), maintenance at a low temperature of 10°C for 2 weeks after treatment. The maximum success rate for chromosome doubling among survivors of perennial ryegrass was 79.1%, and for L. perenne×Festuca arundinacea F1 hybrid embryos it exceeded 40%. The same doubling treatment also works with shoot tip culture in non‐ flowering genotypes obtained by anther culture of L. multiflorum×F. arundinacea hybrids.  相似文献   

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