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SID 5 Research Project Final Report
SID 5 (Rev. 3/06) Page 1 of 22
NoteIn line with the Freedom of Information Act 2000, Defra aims to place the results of its completed research projects in the public domain wherever possible. The SID 5 (Research Project Final Report) is designed to capture the information on the results and outputs of Defra-funded research in a format that is easily publishable through the Defra website. A SID 5 must be completed for all projects.
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Project identification
1. Defra Project code LS3644
2. Project title
Utilisation of selection criteria in white clover to produce varieties that balance production, biodiversity and environmental impact
3. Contractororganisation(s)
Institute of Grassland and Environmental ResearchPlas GogerddanAberystwythCeredigion SY 23 3EB
54. Total Defra project costs £ (agreed fixed price)
5. Project: start date................ 01 July 2003
end date................. 30 June 2007
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6. It is Defra’s intention to publish this form. Please confirm your agreement to do so...................................................................................YES NO (a) When preparing SID 5s contractors should bear in mind that Defra intends that they be made public. They
should be written in a clear and concise manner and represent a full account of the research project which someone not closely associated with the project can follow.Defra recognises that in a small minority of cases there may be information, such as intellectual property or commercially confidential data, used in or generated by the research project, which should not be disclosed. In these cases, such information should be detailed in a separate annex (not to be published) so that the SID 5 can be placed in the public domain. Where it is impossible to complete the Final Report without including references to any sensitive or confidential data, the information should be included and section (b) completed. NB: only in exceptional circumstances will Defra expect contractors to give a "No" answer.In all cases, reasons for withholding information must be fully in line with exemptions under the Environmental Information Regulations or the Freedom of Information Act 2000.
(b) If you have answered NO, please explain why the Final report should not be released into public domain
Executive Summary7. The executive summary must not exceed 2 sides in total of A4 and should be understandable to the
intelligent non-scientist. It should cover the main objectives, methods and findings of the research, together with any other significant events and options for new work.
White clover (Trifolium repens L.) is the most important legume of UK pastures for sheep, beef and dairy production. It is grown with a ryegrass companion, is particularly well suited to grazing management and is a perennial species. It brings the advantages of nitrogen fixation, high protein content and excellent forage quality. This project describes the development of new varieties of white clover with improved persistency, reliability and disease resistance. Novel traits have been incorporated into the germplasm development programme and these will allow new varieties of white clover to contribute to reducing the environmental footprint of livestock production. Genome maps of white clover have been produced and the first comprehensive QTL detection and location study completed.During the period of this work, four new varieties have been added to the National List in England and Wales after successfully demonstrating value for cultivation and use and distinctiveness, uniformity and stability in independent trials. In 2004 the small leaf size variety AberPearl was placed on the Recommended List in E & W and was also categorised as a first choice variety in Scotland. This variety shows exceptional grass plus clover yield for its leaf size and is highly persistent. In 2005 AberAce (a very small leaf, highly grazing tolerant variety) and AberConcord, (a medium leaf size variety with exceptional cold tolerance and early spring growth that performs well across a wide range of applied nitrogen levels) progressed to General Recommendation on the NIAB list and a third, AberDai, became the control variety for medium leaf size. In 2006, three new varieties were added to the NL and they are likely to move to the Recommended List in 2007. AberGuard is a small leaf variety developed with exceptionally high levels of resistance to the main pest of white clover in the UK, stem eelworm (the nematode Ditylenchus dipsaci). In the medium leaf size category, AberJet shows a good contribution to the sward over a number of years as well as high seed yield. AberBoost is the first large leaf variety to be developed from the IGER breeding programme and is well suited to cattle grazing or silage production. New varieties are commercialised through the partnership of the forage breeding programmes at IGER with Germinal Holdings Ltd, show considerable uptake on farm and their use is supported by an extensive programme of knowledge and technology interaction with farmers and seed merchants. A further five varieties are in NL trials. The first is a medium leaf size variety initially derived from a pan European experiment focused on winter hardiness and early spring growth, this is due for NL status in 2007. A further two candidate varieties are due for NL status in 2008. One of these is a small leaf size variety showing exceptional early growth and the other is a large
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leaf type which shows a shifted growth curve with more production early and late in the season and less in mid season. This is desirable since it brings about a better balance of clover protein with ryegrass carbohydrate through the grazing period. A further two varieties, the selection of which was largely for the somewhat cooler, drier climate seen at East Craigs, Edinburgh are due for NL status in 2009. In addition to the IGER, Aberystwyth, site, field based experiments, both plots and individual plant analyses, are also carried out at the East Craigs (Edinburgh) site of the Scottish Agricultural Sciences Agency (SASA). This allows experiments to be carried out under different environmental conditions and has yielded valuable insights into genotype x environment interactions. In addition, the breeding programmes increasingly utilise the IGER upland site at Bronydd Mawr near the Brecon Beacons, both in terms of identifying valuable genetic resources (e.g. plants suited to low P, acidic soils) and for experiments utilising elite germplasm in upland conditions. Field evaluations in plots are carried out under realistic ‘farm’ managements including grazing by sheep and/or cattle.A major focus of the germplasm development programme is the introduction of selection criteria related to a reduced environmental footprint. In particular, we are developing new varieties of white clover aimed at reducing pollution of watercourses and increasing the efficiency of protein use in the rumen, hence reducing nitrogenous wastes including nitrous oxide. New white clover varieties show good yields without applications of phosphorus fertiliser and genetic variation has been identified to further increase phosphorus use efficiency. Significant variation between elite genotypes of white clover with respect to protein content has been detailed. Reduced protein content white clover, together with higher sugar ryegrasses, have the potential to improve the balance of nutrient supply in the rumen, increasing allocation to meat and milk and reducing waste.The germplasm improvement programme is innovative in tools and approaches as well as traits. We have developed the routine implementation of Near Infrared Reflectance Spectroscopy (NIRS) within a breeding programme and use it for measurement of white clover content in mixed swards as well as for quality parameters. A field based NIRS system to allow measurements on fresh samples in situ is now being calibrated. In collaboration with AgResearch, New Zealand and the University of Georgia, USA we are investigating the potential role of heterosis in the development of novel breeding approaches.Backcross hybrids between white clover (as recurrent parent) and the related species ball clover (Trifolium nigrescens) have progressed to submission to NL. These unique hybrids are agronomically like white clover but the introgression of the profusely flowering habit from ball clover has led to a substantial increase in seed yield. Hybrids between white clover and Caucasian clover (T. ambiguum) have been shown in previous work at IGER to be significantly more tolerant of drought than white clover itself with additional benefits in terms of quality. In the period of report the fertility of these hybrids has been increased through selection utilising molecular marker and cytogenetics approaches.The development of marker assisted selection (MAS) approaches is necessary not only for precision breeding in a perennial species but more particularly to facilitate selection for novel traits that will allow new varieties of white clover to contribute to livestock systems with reduced environmental impacts. A comprehensive programme of identifying and locating quantitative trait loci (QTL) for important agronomic, reproductive and physiological traits has been carried out at two field sites over three years and in flowing solution culture. This work, on the first white clover mapping family, has now been supplemented by mapping and QTL analysis on a second mapping family specifically developed to allow analysis of the stolon traits which are key determinants of persistency, productivity, grazing tolerance and survival overwinter. The first QTL for these traits, and for water use efficiency, are described. This work involved the use of molecular markers not only from clovers but also from the model legume Medicago truncatula. The translation of tools and resources from this model to the closely related white clover is likely to be of increasing importance as the variety development programme focuses more and more on traits that will contribute to reduced environmental footprint, particularly cleaner water and reduced emissions to air.Birdsfoot trefoil (Lotus corniculatus) is a forage legume of potential importance for the UK. It contains condensed tannins which slow protein degradation in the rumen and help prevent bloat. This species also has anthelminthic properties and there is evidence to suggest that it also reduces methane emissions from the rumen. However, no UK adapted varieties have been bred and the species is limited in the UK by slow establishment, lack of competitive ability and poor
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winter hardiness. We have combined novel germplasm which is rhizomatous and persistent under grazing in mixed swards with lines of this species with appropriate tannin levels to optimise their beneficial effects.
Project Report to Defra8. As a guide this report should be no longer than 20 sides of A4. This report is to provide Defra with
details of the outputs of the research project for internal purposes; to meet the terms of the contract; and to allow Defra to publish details of the outputs to meet Environmental Information Regulation or Freedom of Information obligations. This short report to Defra does not preclude contractors from also seeking to publish a full, formal scientific report/paper in an appropriate scientific or other journal/publication. Indeed, Defra actively encourages such publications as part of the contract terms. The report to Defra should include: the scientific objectives as set out in the contract; the extent to which the objectives set out in the contract have been met; details of methods used and the results obtained, including statistical analysis (if appropriate); a discussion of the results and their reliability; the main implications of the findings; possible future work; and any action resulting from the research (e.g. IP, Knowledge Transfer).
ObjectivesThere is an increasing need to achieve a sustainable balance between the productivity (and profitability) of grassland-based livestock systems, the quality of their outputs and their environmental impact in terms of diffuse pollution and reduced biodiversity. One approach to this is the generation and uptake by farmers of new forage varieties which better enable this balance to be achieved. White clover (Trifolium repens) is the major forage legume of UK pastures for sheep, beef and dairy sectors. It is a species with considerable merits: nitrogen fixation, highly digestible forage of good mineral content, safe and traceable source of home grown protein. However, with these come challenges of increasing importance in the new economic, policy and consumer environment within which UK agriculture is currently placed. Thus, for instance, it is crucial that fixed nitrogen should be used as efficiently as possible by the ruminant animal and to minimise loses both through excretion and leaching. Germplasm improvement, aided by molecular techniques, has a role to play in moving towards this aim. Similarly, the relatively high phosphate (P) requirement of white clover has effects, largely unquantified at present, on both run off into water courses and on restricting biodiversity.Germplasm development in this programme will address these issues whilst delivering agronomically improved varieties suitable for the production of quality meat and milk.
Specific Objectives
(01) Submission for National List (NL) testing of white clover varieties that allow productivity balanced by reduced environmental impact and, where possible, enhanced biodiversity.(02) Development of innovative approaches to the implementation of selection criteria leading towards varieties described in (i).(03)Spaced plant evaluation of advanced breeding lines and material adapted over long periods to environments (e.g. low input, organic) likely to contain traits important for sustainable agriculture.(04)Evaluation of advanced breeding lines in mixed swards with ryegrass and other species (e.g. Lotus corniculatus -see LS 3643 and LS 3646) under realistic farm managements.(05) Use of molecular marker based approaches to facilitate rapid and precise selection for a range of traits including those relating to utilisation in the animal and/or environmental impact that could not be feasibly undertaken in classical breeding programmes.(06) Submission to NL of novel interspecific hybrids with considerable potential for both production and reduced environmental impact.(07) Improvement in fertility and seed yield of white clover x Trifolium ambiguum backcross hybrids(08) Enhanced agronomic performance of Lotus corniculatus including establishment, persistency and competitive ability in mixed swards.
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All objectives were met in full.
Objective 1In 2004, the small leaf size variety AberPearl was placed on the Recommended List in England and Wales and also in Scotland as a first choice variety. This variety shows exceptional grass plus clover yield for its leaf size and is highly persistent. It is considerably larger in leaf size than the previously recommended AberAce (although both are classed as small leaf) and is complementary to this variety in mixtures for sheep grazing. In 2005, AberAce and AberConcord, progressed to General Recommendation on the NIAB list and a third, AberDai, became the control variety for medium leaf size white clover. In 2006, three new varieties were added to the National List (NL) in England and Wales. These are AberBoost a large leaf size variety, AberJet in the medium leaf size category and AberGuard, a small leaf type with a very high level of resistance to stem nematode. These three varieties were, in 2007, given ‘Provisionally Recommended ‘status. AberGuard was originally derived from a field experiment (outlined below) aimed at ascertaining the effect of resistance to stem nematode (Ditylenchus dipsaci) in the field. AberJet has improved rooting and performs well under both grazing and cutting managements and has a high seed yield. The large leaf variety AberBoost is the first IGER variety of this leaf size and is specifically intended for cattle grazing and silage. It persists well for a variety of this leaf size.A further five varieties are in NL trials. The first is a medium leaf size variety initially derived from a pan European experiment focused on winter hardiness and early spring growth, this is due for NL status in 2007. A further two candidate varieties are due for NL status in 2008. One of these is a small leaf size variety showing exceptional early growth and the other is a large leaf type which shows a shifted growth curve with more production early and late in the season and less in mid season. This is desirable since it brings about a better balance of clover protein with ryegrass carbohydrate through the grazing period. A further two varieties, the selection of which was largely for the somewhat cooler, drier climate seen at East Craigs, Edinburgh are due for NL status in 2009.
Objective 2These varieties extend the portfolio of IGER bred material in terms of both performance and range of managements for which they are suited. Together, they form a strong platform for the delivery of novel traits that will reduce the environmental footprint of livestock systems in the UK.
(a) One such new trait is reduced protein content allowing a diet which, taken together with high sugar grass, delivers a better synchronised supply of protein and carbohydrate to the animal rumen. This, in turn, reduces the potential for nitrogenous (N) pollution of air and water from excreta. Analysis of field grown individual genotypes of elite material has revealed hitherto unexpected levels of variation in protein content in material of both medium and large leaf size (a sample of these data is shown in Table 1). We have developed selection lines of different leaf size with reduced protein content and these have been polycrossed to give progeny which will allow us to (i) determine the heritability of this trait and develop molecular markers for it and (ii)use simulated rumen techniques to quantify the benefits of using these plants in terms of reduced N losses.
Table 1. Variation in protein levels in white clover single plants in the field (mg/g fresh wt)
Medium Large Leaf Leaf
4.57 0.83 2.50 3.79 4.61 4.99 0.65 1.31 0.80 0.95 8.09 2.01 2.69 3.77 1.35 4.04 3.31 2.28 1.09 0.72
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(b) During the course of this project we have pioneered the use of near infra-red reflectance spectroscopy (NIRS) for the routine analysis of clover content in mixed swards as part of plot assessment of potential varieties. This has replaced laborious hand separation of clover and grass followed by drying and weighing of separated samples. NIRS is also used for measurement of quality parameters e.g. dry matter digestibility (DMD), nitrogen (N) and water soluble carbohydrate (WSC) content. In 2006, a successful bid for funding to the BBSRC Research Equipment Initiative (REI) allowed the purchase of field based NIRS equipment. This is now being calibrated and when fully operational will allow analyses to be carried out on fresh samples in the field rather than on dried and milled samples. Initial observations show that for clover content this equipment is likely to be accurate and robust.
Figure1. Preliminary calibration for clover content using field based NIRS
(c) Work in this project also encompasses new approaches to variety development in outbreeding species. As an example, we are engaged in collaboration with AgResearch, New Zealand and the University of Georgia to investigate the potential for heterosis breeding and the extent to which white clover can be geographically categorised into heterotic groups. In this experiment a large number of crosses were carried out (in New Zealand) between 25 varieties sub divided into categories according to the place from which the germplasm predominantly used in those varieties originated. Crosses were carried out both within and between categories and seed sown at the three sites in 2006.
(d) White clover is considered to have a medium to high requirement for phosphorus (P). Reductions in P fertiliser use are an important long term strategy in reducing pollution of watercourse, in compliance with the EU Water Framework Directive. We have carried out a field experiment to evaluate performance of elite material with and without the addition of P fertiliser. The results (Table 2) show that over three years yield gains from P fertilisation are relatively modest and that variation exists for the development of varieties with further improvements in performance without added P (e.g. Ac 4630 gives more dry matter yield without P fertiliser). These results may be of significance in terms of revising current recommendations to farmers as to the extent of P fertiliser application needed with modern white clover varieties. This work is allied to that in LS3646 in which germplasm is assessed for its ability to perform well on soils with intrinsically low P levels.
(i) No PClover DM yields kg/ha
2004 2005 2006 TotalAberPearl 4735 7445 3760 15940AC 64 4563 8185 4625 17373
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Ac 4489 4235 6560 4174 14969Ac 4490 3259 5736 3581 12576Ac 4512 3968 7319 3765 15052Ac 4629 2944 6349 2894 12187Ac 4630 3742 7301 4192 15235Ac 4631 4222 5919 3105 13246Ac 4642 4701 6740 3695 15136
Mean 4041 6839 3755 14635
Significance * * nss.e.d 442.2 550.3 665.9l.s.d 937.5 1166.6 1411.5
(ii) with P Clover DM yields kg/ha
2004 2005 2006 Total
AberPearl 4835 7873 3917 16625AC 64 4799 8237 4124 17160Ac 4489 4239 7720 4536 16495Ac 4490 3358 6036 3460 12854Ac 4512 3952 7735 5165 16852Ac 4629 4480 6873 4150 15503Ac 4630 3871 6947 4090 14908Ac 4631 4020 5916 4096 14032Ac 4642 4925 6477 4023 15425
Mean 4275 7090 4173 15539
Significance ns ns nss.e.d 470.0 1058.3 576.3l.s.d 998.4 2243.4 1221.8
Table 2 Performance of white clover lines with and without added phosphorus fertiliser. Field plots with perennial ryegrass and white clover under continuous sheep grazing. Total of 6 cuts/year. P added at100kg/ha/yr to the plots with P.
(e) Although many of the traits currently being incorporated into breeding programmes are aimed at reducing environmental impacts, plant persistence remains important. White clover brings with it substantial savings in the use of nitrogen fertiliser (around 150Kg/ha/yr is fixed by a sward with clover content of 35-40%) and this in turn brings down the substantial greenhouse gas emissions from the Haber process. Thus persistence and maintenance of clover content such that N fertiliser is not needed are important objectives. In the UK, the major pest contributing to lack of white clover persistence is stem nematode. A field experiment to analyse the impact of resistance to stem nematode (Ditylenchus dipsaci) concluded during 2005. Plant lines resistant (R) or susceptible (S) to the nematode, but otherwise closely related, were evaluated in plots with perennial ryegrass under cutting and grazing and with/out the addition of the nematode. The impact of grazing on clover dry matter yield was greater than that of the nematode and the R line gave higher yields under all circumstances. Nonetheless, the impact of resistance could be seen. The R line yielded 6% and 11% more than the S line under cutting and grazing respectively without added nematode and 20% and 41% more with infestation. The resistant line was used as the basis for the small leaf variety AberGuard which gained provisional recommendation in 2007.
Objective 3
Accessions of white clover from Italy and from the Spanish Pyrenees have been characterised in plots and as individual genotypes. Evaluation of 39 populations from the Italy was completed in 2005 and 43 populations from the Pyrenees were fully assessed in 2006. This material is likely to be of
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considerable value in enhancing characteristics suitable for more environmentally benign livestock systems e.g. incorporation of N and P from manures rather than fertiliser.Seed production of novel material was carried out at a range of scales (field, polytunnel and glasshouse) with a total of 92 different lines of white clover being multiplied in 2005 for future field experiments. A similar number of lines were multiplied in 2006.Analysis of individual genotypes takes place at different stages of the breeding cycle. In addition to the analysis of genetic resources from collections as described above, it also occurs at a later stage of the breeding programme where elite material is placed into leaf size categories and also evaluated with respect to other morphological features.Individual spaced plants of white clover are measured when approximately 90-95% of the plants have flowered. The following recordings are made:
Plant height is measured at the tallest point of the foliage.Height of the tallest flower is measured.Width of the plant measured at the widest horizontal axis of the plant.
The following characters are recorded on a rapidly growing stolon where an unfolded trifoliate leaf on the third node away from the tip is measured:
Leaflet length is measured on the central leaflet and measured from the base to the tip.Leaflet width is measured at its widest point.Petiole length is measured from the node to the base of the central leaflet.Internode length is measured between the third and fourth nodes.If necessary, the thickness of the stolon is measured using callipers.
Table 4 gives an illustration of data obtained from evaluations of individual plants
Flowerin
g Plant Plant Flower Leaf Leaf Internode Petiole Growth Flower Leaf
DateHeigh
t Spread HeightLengt
h Width LengthLengt
h Score Score Area cm cm cm mm mm mm mm 0 - 5 0 - 5 mm2
Ac 4831 61.37 23.79 81.87 28.23 25.47 17.88 29.87 109.76 3.85 3.21 475.81Ac 4832 61.32 26.88 92.21 33.14 30.33 25.05 28.25 137.78 4.00 2.89 794.08Ac 4833 60.89 21.43 71.59 26.53 26.38 20.39 25.24 95.95 3.24 2.86 561.42Ac 4834 60.01 17.93 85.19 23.34 19.76 16.53 27.40 89.29 3.43 3.09 343.93S 184 60.06 25.77 91.38 31.79 28.26 22.54 31.82 117.26 3.83 2.95 649.54Ac 4593 62.42 36.32 97.11 37.00 46.58 34.24 24.39 169.76 4.21 2.79 1631.32Menna 56.34 30.55 97.38 37.23 34.43 25.78 29.13 147.03 4.18 3.15 909.98Alice 58.72 33.79 105.00 38.67 41.69 30.85 29.67 179.82 4.05 2.85 1308.59AberDai 58.70 28.70 92.95 34.90 34.15 26.00 26.33 149.38 3.83 3.10 917.60AberJet 59.71 32.42 98.27 38.77 47.11 32.14 33.33 190.43 4.08 3.13 1078.38AberBoost 61.32 35.36 110.00 38.95 50.90 37.38 29.08 178.72 4.43 2.55 1938.72Aran 60.98 35.10 100.18 40.60 50.00 38.65 29.55 198.50 4.30 2.93 1996.43
Table 4. Individual plant data for 2006 showing selection lines compared to a number of controls in all leaf size categories.
Objective 4Although considerable information can be obtained from the analysis of the performance of individual genotypes as single plants in the field it is well established that, for white clover, this does not necessarily correlate well with performance in plots with a ryegrass companion. Thus extensive evaluation of breeding lines and candidate varieties is necessary under conditions that are close as possible to the use on farm. For small leaf types continuous grazing by sheep is used, with exclusion cages allowing measurement of productivity. For medium leaf type varieties rotational sheep grazing together with cattle grazing and some times a cut for silage will be used and for large leaf types lax cattle grazing and silage cuts. In addition to the IGER, Aberystwyth, site, field based experiments, both plots and individual plant analyses, are also carried out at the East Craigs (Edinburgh) site of the Scottish Agricultural Sciences
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Agency (SASA). This allows experiments to be carried out under different environmental conditions and has yielded valuable insights into genotype x environment interactions. In addition, the breeding programmes increasingly utilise the IGER upland site at Bronydd Mawr near the Brecon Beacons, both in terms of identifying valuable genetic resources (e.g. plants suited to low P, acidic soils) and for experiments utilising elite germplasm in upland conditions (see LS3646). In 2005, as an example, new white clover field experiments were established as both plots (total of 48) and individual plants (1304). These joined similar numbers for each of the three previous years, since most field experiments with white clover will be carried out for at least three to four years. Most of the field based evaluations used a randomised complete block design with four replicates. Mixed white clover/ perennial ryegrass plots of 1.5 x 3.5m were used. Tables 5 and 6 give examples of data obtained from plot based field evaluation
Clover DM yield kg/ha Total DM yield kg/ha
Variety 2004 2005 Total (2 years) 2004 2005 Total (2 years)
AC 65 4252 6199 10451 10256 9910 20166
Ac 4491 3342 5303 8645 9981 8839 18820
Ac 4492 3147 5344 8491 9485 9140 18625
Ac 4496 3298 5181 8479 9732 9287 19019
AberConcord 3661 5627 9288 10468 9385 19853
AberDai 3746 6233 9979 10461 10441 20902
Crusader 3450 5534 8984 10403 9173 19576
Mean 3556 5632 9188 10112 9454 19566
Significance ns ns ns ns
s.e.d. 977.6 1042.3 1472.6 598.2
Table 5. Yield of medium leaf white clover selection lines and varieties and total sward yields under a rotational sheep grazing management. The experiment was conducted at IGER, Aberystwyth with a perennial ryegrass companion
Clover DM yield kg/ha Total DM yield kg/ha
Variety 2005 2006 Total 2005 2006 Total ( 2 years)Ac 4626 4320 2630 6950 9857 9784 19641Ac 4627 4818 2339 7157 10092 9611 19703Ac 4701 5815 3327 9142 11229 10125 21354Ac 4633 5106 3150 8256 10679 9350 20029Ac 4634 4875 4035 8910 10265 10834 21099Ac 4635 7469 4244 11713 12235 10544 22779Ac 4636 7227 3517 10744 12219 11384 23603Ac 4689 6537 4427 10964 11551 11225 22776Ac 4690 7671 4751 12422 11796 11338 23134Ac 4691 6890 3551 10441 11899 10073 21972Alice 8086 3983 12069 11702 11005 22707Aran 7870 4055 11925 12253 10772 23025
Mean 6390 3667 10058 11315 10504 21819
Significance ** ns * nss.e.d. 934.7 786.2 744.7 1039.6l.s.d. 1630.5 2156.0
Table 6 Yield of medium and large leaf selection lines with large and very large controls and total sward yields under a rotational sheep and cattle grazing management
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Objective 5
The first genome map of white clover was published in 2003, the result of a collaboration between IGER and the Plant Biotechnology Centre, Victoria, Australia. This has now been used in the generation of a considerable amount of information on quantitative trait loci (QTL) of both morphological and reproductive characters (including seed yield). Phenotypic data was taken from individual plants of the F2 mapping family over several years at both IGER and East Craigs, giving considerable information on QTL x Environment interactionsField data were collected on cloned genotypes replicated in space and time and included details of a large number of agronomic and reproductive traits. The former category included the following traits:
Flowering date Green weightHeight of tallest flowerInternode lengthLeaf area, length and widthPetiole lengthPlant height and spreadHeritabilities for these traits ranged from 19-54%.
The reproductive traits assessed were: FertilityNumber of floretsNumber of flowersPeduncle girth and peduncle lengthSeeds per flowerSeed yieldThousand seed weight
Heritability values ranged from 11-79%
This approach allowed a meta-analysis of QTL location to be carried out, the results of which are summarised below.
Agronomic traits
62 QTL of LOD range 2.1 - 4.9 (IM) 2.8 - 7.4 (CIM)9 QTL on LG7 associated with leaf morphology in different spatial and temporal replicates.Co-incidence of leaf trait QTL with QTL for: plant spread (LGs 2, 3, 6, 7, 8, 12), height (LGs 2,3,12) and internode length (LGs 2,3,8).
Reproductive traits
24 QTL identified including seed yield LOD range of 2.3 - 5 (IM) 3 - 5.5 (CIM)Co-incident QTL on LGs 2 and 3
QTL Analysis was also carried out on a range of traits measured on plants growing in flowing solution culture (FSC) at IGER. This involved 11-fold replication of plants and a 50-day ‘nursery period’ followed by 14-day screen. Measurements were taken at days 0, 7 and 14.
In this experiment, traits measured included:
relative growth rate (RGR)leaflet mass, leaf area shoot mass, root mass and nodule mass root: nodule mass ratioshoot: root ratio
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shoot nitrogenstolon lengthleaf area: stolon mass ratio
From the flowing solution culture experiment: 24 QTL were identified.Clusters of coincident QTL for correlated traits were seen on LGs 1, 5 and 8Co-location with morphogenetic traits from field analysis was observed e.g. FSC leaf area: stolon mass QTL co-locates with field leaf length and leaf width QTLs on LG2.An example of the QTL effects detected is shown below for two linkage groups:
The horizontal stem, or stolon, of white clover is a distinctive feature largely responsible for this species grazing tolerance and ability to spread through the sward. Selection for productivity, persistence and overwinter survival is largely based on stolon attributes.In order to map stolon traits, a crossing program between four lines, the products of two generations of divergent selection from the variety AberCrest was carried out in 2002 to produce a mapping family of 350 plants. This family was a cross between a plant showing thick profuse (TKPR) stolons (the female) and a plant with thin sparse stolons (TNSP). Progeny were replicated three times and planted out in the field in 2004 for a detailed survey of the stolon characteristics, which were used for QTL analysis. Ten characteristics were measured which were divided into three categories:1. Stolon morphology: stolon length and width, internode and petiole length.2. Plant and leaf morphology: leaflet length and width, plant height and spread.3. Flowering date and height of peduncles.
Broad sense heritability (BSH) was calculated for these traits.Trait Flowering
dateFlowerheight
Plantheight
Plantspread
Stolonwidth
Stolon number
Internodelength
Leaf length
Leafwidth
Petiolelength
BSH 0.39 0.24 0.32 0.30 0.41 0.38 0.50 0.34 0.35 0.27
96 randomly selected plants were also used in a preliminary experiment analysing differences in water use efficiency (WUE) experiment. This experiment involved a further five QTL measurements of: mean total, root and shoot mass, root-shoot ratio and the water use efficiency of the plant.Mapping was performed using Amplified Fragment Length Polymorphism (AFLP) and Simple Sequence repeat (SSR) markers. SSRs from white clover, gene based M. truncatula derived markers developed in the EU Grain Legume Integrated Project (GLIP) and EST derived SSRs from M.
SID 5 (Rev. 3/06) Page 12 of 22
truncatula were used. Marker detection used an ABI3700 genetic analyser. JoinMap v3.0 was used to produce the molecular marker map and MapQTL v4.0 was used to align the traits measured in the field and the WUE data to the marker map.For an F1 cross between heterozygous individuals, two maps are produced, one for each of the parental genotypes. The TKPR map (Map 1) has 154 markers over 710cM on 16 linkage groups, on average 5cM between markers. The TNSP map (Map 2) is shorter with 86 markers on 13 linkage groups over 524 cM. QTL analysis of the traits for the TKPR data generated a map which had 12 QTL on 10 of the linkage groups (Map 3). TNSP data generated a map which had 11 QTL on 8 of the linkage groups (Map 4).
SID 5 (Rev. 3/06) Page 13 of 22
Map 1 TKPR molecular map
SID 5 (Rev. 3/06) Page 14 of 22
E 3 2 -M 4 8 .1 1P 2 3 -M 3 9 .2 9m tm tg e n 0 0 1 2 1 _ 0 2 _ 1 .2E 3 8 -M 4 7 .4E 3 5 -M 5 3 .6P 2 3 -M 3 9 .1 0P 2 3 -M 3 9 .7P 2 3 -M 3 9 .2 2p 1 4 -m 3 3 .6 5P 2 3 -M 3 9 .1 9P 2 3 -M 3 9 .6m tm tg e n 0 0 1 2 1 _ 0 2 _ 1 .3P 2 3 -M 3 9 .4P 2 3 -M 3 9 .1E 3 8 -M 5 4 .6P 2 3 -M 3 9 .2 6E 3 6 -M 4 9 .2P 2 3 -M 3 9 .2 0P 2 3 -M 3 9 .1 7P 2 3 -M 3 9 .8P 2 3 -M 3 9 .1 6p 1 4 -m 3 3 .5 1P 2 3 -M 3 9 .5M tB A 3 9 B 0 5 F 1 .3P 2 3 -M 3 9 .9P 2 3 -M 3 9 .3P 2 3 -M 3 9 .2 4p 1 4 -m 3 3 .3 2P 2 3 -M 3 9 .1 4p 1 4 -m 3 3 .2 4P 2 3 -M 3 9 .2 1P 2 3 -M 3 9 .2 5p 1 4 -m 3 3 .1 9P 2 3 -M 3 9 .2 8p 1 4 -m 3 3 .2 0P 2 3 -M 3 9 .2 3p 1 4 -m 3 3 .6 1P 2 3 -M 3 9 .2 7P 1 2 -M 3 3 .1 4P 2 3 -M 3 9 .1 8P 2 3 -M 3 9 .1 5P 1 7 -M 5 1 .1 3p 1 4 -m 3 3 .2 3M tB A 1 9 C 1 2 F 1 .4p 1 4 -m 3 3 .1 6E 3 1 -M 4 7 .8p 1 4 -m 3 3 .3 9p 1 4 -m 3 3 .5 0p 1 4 -m 3 3 .4 5P 2 3 -M 3 9 .2p 1 4 -m 3 3 .4 2p 1 4 -m 3 3 .7 7
1
p 1 4 -m 3 3 .5 4p 1 4 -m 3 3 .2 2p 1 4 -m 3 3 .5 6p 1 4 -m 3 3 .6 0p 1 4 -m 3 3 .5 3p 1 4 -m 3 3 .6 6p 1 4 -m 3 3 .8 2
2
E 3 9 -M 6 1 .2E 3 6 -M 5 4 .4E 3 8 -M 5 6 .4
E 4 2 -M 5 2 .5
E 3 1 -M 5 4 .5
E 3 1 -M 6 0 .7
E 3 2 -M 4 8 .2
E 3 5 -M 4 9 .4p 1 4 -m 3 3 .7 5
m tca e st0 0 2 1 3 _ 1 1 _ 2 .2
a t s0 7 0 .1
m tm tg e n 0 1 0 9 9 _ 0 1 _ 1 .1
m tm tg e n 0 1 0 9 _ 9 0 _ 1 1 .1m tm tg e n 0 1 1 2 _ 3 0 _ 2 1 .1
3
P 2 0 -M 4 4 .1 6
P 1 2 -M 3 3 .3 9p 1 4 -m 3 3 .1P 2 0 -M 4 4 .7
P 1 2 -M 3 3 .3 3p 1 4 -m 3 3 .7 0P 2 0 -M 4 4 .1 0P 2 0 -M 4 4 .5P 2 0 -M 4 4 .8P 2 0 -M 4 4 .3P 1 2 -M 3 3 .4 6P 1 2 -M 3 3 .2 4P 1 2 -M 3 3 .4 0P 1 2 -M 3 3 .7P 1 2 -M 3 3 .4 3
P 1 2 -M 3 3 .3 5
4
P 1 2 -M 3 3 .4 8
P 1 2 -M 3 3 .3
P 2 0 -M 4 4 .2 1
P 1 2 -M 3 3 .2P 2 0 -M 4 4 .2 0
a ts0 7 0 .7
a ts0 7 0 .5p 1 4 -m 3 3 .2 9
P 2 0 -M 4 4 .1p 1 4 -m 3 3 .4 6
5
E 3 1 -M 4 7 .2
A 0 2 A 0 5 . 1
E 3 2 -M 6 0 .6m tm tg e n 0 0 0 5 3 _ 0 1 _ 1 .2E 3 1 -M 6 0 .1E 3 1 -M 6 0 .9E 3 1 -M 6 0 .6E 3 1 -M 6 0 .1 0
6
05
1 01 52 02 53 03 5
4 04 55 05 56 0
6 57 07 58 08 59 0
9 51 0 01 0 51 1 01 1 5
1 2 01 2 51 3 01 3 51 4 0
P 1 7 -M 5 1 .1 4
P 1 7 -M 5 1 .1 5
P 1 7 -M 5 1 .1 6
7
m tm tg e n 0 1 1 1 1 _ 0 1 _ 1 .3m tm tg e n 0 1 1 1 1 _ 0 1 _ 1 .4
m tm tg e n 0 1 1 1 1 _ 0 1 _ 1 .6
8
P i sg e n _ 2 1 _ 1 _ 1 .2
M tB A 3 9 B 0 5 F 1 .4
a t s0 5 4 .2a t s0 5 4 .4
m tm tg e n 0 1 1 2 _ 9 0 _ 2 1 .6m tm tg e n 0 1 1 2 _ 9 0 _ 2 1 .7P i sg e n _ 2 1 _ 1 _ 1 .1
9
m tm tg e n 0 0 3 4 6 _ 0 9 _ 1 .3m tm tg e n 0 0 2 7 4 _ 0 4 _ 1 .1m tm tg e n 0 0 3 4 6 _ 0 9 _ 1 .1m tm tg e n 0 0 2 5 7 _ 0 3 _ 2 .3m tm tg e n 0 0 2 7 4 _ 0 4 _ 1 .2m tm tg e n 0 0 2 7 4 _ 0 4 _ 1 .3m tm tg e n 0 0 3 4 6 _ 0 9 _ 1 .2m tm tg e n 0 0 2 5 7 _ 0 3 _ 2 .1
1 0
m tm tg e n 0 1 1 2 _ 9 0 _ 2 1 .2m tm tg e n 0 1 1 2 _ 9 0 _ 2 1 .5
m tm tg e n 0 1 1 2 _ 9 0 _ 2 1 .1m tm tg e n 0 1 1 2 _ 9 0 _ 2 1 .4
1 1
E 3 1 -M 6 0 .8
E 3 8 -M 5 4 .3
E 4 2 -M 5 2 .1
A 0 1 C 1 0 . 2
a t s2 2 6 .4
a t s2 2 6 .3
M tB A 2 6 A 0 4 F 1 .3
1 2
E 3 9 -M 6 1 .4
B 0 1 E 0 7 . 1
B 0 1 E 0 7 . 3
p rs5 1 0 .1
E 3 2 -M 6 0 .8
1 3
051 0
1 52 0
2 53 03 5
4 04 5
5 05 56 0
6 57 0
7 58 08 5
9 09 5
1 0 01 0 5
1 1 01 1 51 2 0
1 2 51 3 0
1 3 51 4 0
P1 7 -M 5 1 .1 1
P1 7 -M 5 1 .1 7
14
p rs6 4 5 .2p rs6 4 5 .3
p rs6 4 5 .1
15
p rs2 5 6 .2
m tm tg e n 0 1 1 1 1 _ 0 1 _ 1 .2
m tm tg e n 0 0 2 5 _ 1 0 _ 6 1 .1
16
051 01 52 02 53 03 54 04 55 05 56 06 57 07 58 08 59 09 51 0 01 0 51 1 01 1 51 2 01 2 51 3 01 3 51 4 0
Map 2 TNSP molecular map
SID 5 (Rev. 3/06) Page 15 of 22
E42-M 60.7
Pisgen_21_1_1.4
P12-M 33.37
E42-M 52.2
E42-M 60.6
1 3
05101520253035404550556065707580859095100105110
p 1 4 -m 3 3 .2 9a ts0 7 0 .5
a ts0 7 0 .7P 1 2 -M 3 3 .4 5P 2 0 -M 4 4 .2 0
P 1 2 -M 3 3 .3
P 2 0 -M 4 4 .2 1
7
E 3 5 -M 4 9 .9
a ts2 2 6 .2
a ts2 2 6 .5
E 3 2 -M 6 0 .7
8
P isg e n _ 2 1 _ 1 _ 1 .2
M tB A 3 9 B 0 5 F1 .4
a ts0 5 4 .2
a ts0 5 4 .3
P isg e n _ 2 1 _ 1 _ 1 .1
9
m tm tg e n 0 1 1 1 1 _ 0 1 _ 1 .3m tm tg e n 0 1 1 1 1 _ 0 1 _ 1 .4
m tm tg e n 0 1 1 1 1 _ 0 1 _ 1 .6
1 0
B 0 1 E 0 7 .2
E 3 8 -M 5 4 .2
E 3 7 -M 6 1 .3
1 1
m tm tg e n 0 0 5 7 _ 0 0 _ 2 1 .2m tm tg e n 0 0 5 7 _ 0 0 _ 2 1 .3
m tm tg e n 0 1 1 1 _ 1 0 _ 1 1 .2
1 2
051 01 52 02 53 03 54 04 55 05 56 06 57 07 58 08 59 09 51 0 01 0 51 1 0
p14-m 33.72
p14-m 33.38p14-m 33.42p14-m 33.39p14-m 33.45p14-m 33.16p14-m 33.58P20-M 44.16M tBA19C 12F 1.4P12-M 33.14p14-m 33.61p14-m 33.23P20-M 44.18p14-m 33.19p14-m 33.51P20-M 44.7
P20-M 44.11
P20-M 44.5P20-M 44.8P20-M 44.10
P20-M 44.14
p14-m 33.1
1
p14-m 33.82p14-m 33.66p14-m 33.53p14-m 33.60p14-m 33.56p14-m 33.22p14-m 33.54
2
P23-M 39.23P23-M 39.4P23-M 39.11P23-M 39.5P23-M 39.3P23-M 39.9P23-M 39.24P23-M 39.16P23-M 39.17P23-M 39.6
3
B02E01.1A02C 03.1B02E01.3A06B07.2
4
p14-m 33.64
E36-M 54.4E38-M 56.4
5
m tm tgen00053_01_1.5
m tm tgen00053_01_1.1m tm tgen00053_01_1.2E32-M 60.6E31-M 60.1E31-M 60.9m tm tgen00053_01_1.4E31-M 60.6E31-M 60.10
psates t00169_03_3.2
6
05101520253035404550556065707580859095100105110
Map 3 Thick profuse QTL map
Map 4 Thin sparse QTL map
SID 5 (Rev. 3/06) Page 16 of 22
TKPR QTL map
PS
FH MR
MIL
RS
WU
E
RS
R
1
WU
E
2
ILR
SR
SW
RS
RW
UE
WU
EM
RM
3
MTM
4
IL
6
FH
7
LL
IL
9
FH
PH
SN
SW
12P
L13
PL
16
TNSP Q TL m a p
RSR
MR
MSN
SWSN
FHFD
1
LL
3
SN PL
4
RSR
MR
M
WU
E
IL
5
MR
M
MTM
6
MR
M MSM
7
PLLL
FD WU
E
9
PH
PL
12
KEY Stolon Characteristics (SW , SN, IL, PL) Leaf/P lant Characteristics (LL, LW , PH, PS) W ater Use Efficiency Characteristics (W UE, MSM, MRM, MTM, RSR) Flowering characteristics (FD , FH)
In addition, further QTL analysis on a different mapping population, construction of a white clover BAC library and preliminary analysis of microsynteny between white clover and the model legume Medicago truncatula have been carried out through a Walsh Fellowship in conjunction with Teagasc , Oak Park, Ireland.
Objective 6
In 2006 the first submission, anywhere in the world, of an interspecific hybrid involving white clover to a National List trialling system, prior to commercialisation, was achieved. These are hybrids between white clover and the annual, diploid, profusely flowering ball clover (Trifolium nigrescens). A range of studies have been carried out to show that third generation backcross hybrids with white clover as the recurrent parent are agronomically very similar to white clover in terms of dry matter yield, persistence, quality and nitrogen fixation.
Table 7. Inflorescence production and seed set of BC3 hybrids between white clover and T. nigrescens
Variety/hybrid Inflorescences /m2 Seedset
AberDale (s) 569 2.8Menna (m) 322 1.9Olwen (l) 326 2.4BC3 (s) 559 2.5BC3 (m) 549 2.3BC3 (l) 672 2.9
Significance *** NS
*** p<0.001, NS not significant
Backcross hybrids (BC3) between white clover and the related species Trifolium nigrescens (Ball clover) have been shown to have considerably enhanced seed yield without compromising agronomic or quality traits. The improved seed yield of hybrids has been shown in replicated field plot experiments to be derived from significantly enhanced inflorescence production compared to that of the control varieties, particularly in the medium and large leaved types with no negative effect on fertility (seedset) (Table 7). Inflorescence production of the BC3 (small leaved) was comparable with the high seed yielding control variety AberDale. The first variety from this work was submitted to NL in 2006 and use of this material in ongoing crossing programmes will greatly facilitate the economic production (and therefore uptake) of white clover varieties with traits focused on improved quality and reduced environmental impacts.
Objective 7A second series of backcross hybrids, between white clover and Trifolium ambiguum (Caucasian clover) has produced material with increased drought tolerance, lower protein and higher water soluble carbohydrate (see LS 3643) .
An extensive range of studies over a number of years (largely in LS 3643) has confirmed the potential of both T. repens x T. nigrescens and T. repens x T. ambiguum third generation backcross hybrids (with white clover as recurrent parent). In the reporting year seed multiplication of both sets of hybrids has been carried out to allow confirmation of the stable introgression of key traits. This has been complemented by genomic in situ hybridisation (GISH) studies carried out under a Royal Society Fellowship by Dr Violetta Kotseruba of the Institute of Cytogenetics, St. Petersburg, Russia. GISH analyses have shown the extent of introgression into the white clover genome and in combination with molecular markers studies will allow rapid and precise marker assisted selection for introgressed traits. A range of crosses have been undertaken to create white clover lines of different leaf size with the
SID 5 (Rev. 3/06) Page 17 of 22
rhizomatous trait from T. ambiguum. Table 8 gives an example of the data obtained from evaluation of seed set in individual backcross genotypes.
Table 8. Seed set (Seeds per floret) of advanced backcrosses (BC1 and BC2) of T. repens x T.ambiguum hybrids
Genotype Seed set Genotype Seed set Genotype Seed setBC1 3 0.15 BC1 47 0.07 BC2 417 0BC1 8 0.21 BC1 68 0.03 BC2 420 0.89BC1 11 0.24 BC1 71 0.03 BC2 422 0.06BC1 35 0.27 BC1 81 0.25 BC2 424 0.02BC1 38 0.23 BC1 251 0.03 BC2 431 1.36BC1 40 0.19 BC1 254 0.04 BC2 445 0.28BC1 73 0.13 BC1 305 0.14 BC2 462 0BC1 76 1.13 BC1 312 0.05 BC2 458 0.18BC1 82 0.25 BC1 409 0.03 BC2 466 0.16BC1 110 0.01 BC2 468 0BC1 121 0.15 BC2 475 0.14BC1 340 0.21 BC2 491 0.1BC1 345 0.24
Further crosses have been carried out to incorporate increased fertility along with the rhizomatous trait, prior to submission to NL.
Objective 8
Birdsfoot trefoil (Lotus corniculatus) has considerable advantages as a forage legume: it is tanniferous, has anthelminthic properties and may help to reduce methane emissions from cattle. However, no germplasm bred for UK conditions has been produced and introduced material is generally agronomically poor in terms of establishment, competitive ability and overwinter survival.
In an initial study, 680 individual plants of Lotus corniculatus and Lotus uliginosus derived from varieties and selection lines were evaluated for agronomic traits (see LS 3643). Significant variation was identified for DM yield and persistence. Dry matter yield was greatest in the variety Emlyn and lowest in A10528/00. This latter variety had the highest condensed tannin content and was the most persistent.
0
50
100
150
200
250
300
Inbred
lines
George
a
Steadfa
st
Carrol
Lotar
MU81
ARS 2620
Viking Le
o
Grassla
nds M
aku
All-Dew
ey
Norcen
Gran S
an G
abrie
lleEmlyn
Upstar
t
Grassla
nds G
oldie
Sunris
e
A1 052
8/00
Dawn
Terre
Ober
Fergu
s
Empire
Inia D
raco
Variety
Dry
mat
ter y
ield
(g/p
lant
)
Dry weight JuneDry weight September
SID 5 (Rev. 3/06) Page 18 of 22
Figure 2. Dry matter yield of spaced plants of Lotus corniculatus and Lotus uliginosus. Data is presented as a mean of 20 spaced plants +/- standard error of the mean.
A novel rhizomatous type of Lotus corniculatus, ‘Highgrove’, was characterised during this work and a total of 131 hand-crosses were carried out in 2005/6 with genotypes of Lotus corniculatus (see LS3643 and LS3646) to combine the characteristics of appropriate tannin content, rhizomatous growth and field performance. At the same time further field evaluations were carried out to identify genotypes within Highgrove that could form the basis of variety development following further crosses. Table 9 gives an illustration of the data obtained from evaluation of individual genotypes.
Technology Transfer
An important aspect of the work of this project is involvement in technology transfer activities with farmers and seed merchants concerning variety benefits, appropriate management systems and wider issues of using best practice. To some extent this is carried out with the Grassland Development Centre (GDC) based at IGER, Aberystwyth but extensive technology transfer activities are also carried out in conjunction with Germinal Holdings. These include frequent visits from farmers’ groups and seed merchants to the breeding plots, Open Days, displays at shows and articles in the farming press and other media. In addition, IGER plant breeding staff run an annual training course for seed merchants, supported by Germinal Holdings. Technical booklets are produced including a clover Management guide and presentations were made at the Forage 365 meeting in 2006. Recently we have collaborated with the Defra supported LEGNET programme aimed at increasing the farmer knowledge base and uptake of white clover in particular. In July 2007 an inaugural and very successful ‘legume day’ for around 50 seed retailers was held at IGER and, in conjunction with the GDC, at a nearby farm.
In addition a number of presentations of results have been given at international conferences (described in previous reports) and peer reviewed papers published in international journals (see below).
Exploitation of results
Plant breeders’ rights are obtained by IGER for varieties produced from this programme. New varieties developed in this work are entered for NL and RL, commercialised (including seed production) and marketed by Germinal Holdings Ltd, the commercial partner of forage breeding at IGER.
SID 5 (Rev. 3/06) Page 19 of 22
Future work
During the latter stages of this project we have carried out preliminary studies combining data from our experiments, and knowledge of the genetic architecture of key traits with models of nutrient and energy flows (e.g. N GAUGE, SIMS DAIRY) developed at IGER North Wyke to quantify, on a whole farm basis, the outcomes of using improved white clover varieties to reduce N pollution of water and air. Future work will build on this integration and in particular will focus on the areas of reducing N and P pollution of watercourses, reducing emissions to air and adaptation of UK pastures to climate change.
Similarly, we have utilised information acquired over many years in respect of methods of reducing P pollution to quantify the benefits of ongoing breeding (e.g. for increased P use efficiency) at a catchment scale. This work has demonstrated the great opportunity for a strong linkage between experimental studies, focusing on genetic improvement, and modelling to develop an iterative cycle that informs and develops approaches to variety development within a systems context. This will enhance our capability to produce varieties that contribute to a truly multifunctional agriculture supporting both economic and environmental sustainability.
Molecular tools, strengthened by translation of resources from the model species Medicago truncatula, will be employed to deliver the precision breeding required to fully capitalise on systems based approaches. The foundation for this has now been laid in terms of QTL analysis and we have carried out studies of both macro and micro synteny between white and M. truncatula which will underpin new advances. An IGER-led international consortium the International Trifolium Network (ITN) was established in 2005 to facility translation from M. truncatula to clovers and this is now supported by funding through the European Research Area Network in Plant Genomics for a major programme of physical mapping including cytogenetics and BAC end sequencing in red clover (Trifolium pratense) with considerable implications for future developments in white clover.
SID 5 (Rev. 3/06) Page 20 of 22
References to published material9. This section should be used to record links (hypertext links where possible) or references to other
published material generated by, or relating to this project.Williams, T. A., Abberton, M.T. and Rhodes, I. (2003) Performance of white clover varieties combined in blends and alone when grown with ryegrass under sheep and cattle grazing. Grass and Forage Science 58, 90-93.
T. A. Williams, D. R. Evans, I. Rhodes and M. T. Abberton (2003) Long-term performance of white clover varieties grown with perennial ryegrass under rotational grazing by sheep with different nitrogen applications Journal of Agricultural Science 140, 151-159.
Jones, E.S. L. J. Hughes, M. C. Drayton, M. T. Abberton, T. P.T. Michaelson-Yeates, C. Bowen and J. W. Forster(2003) An SSR and AFLP molecular marker-based genetic map of white clover (Trifolium repens L.) Plant Science 165, 447-479.
Abberton, M. T., Michaelson-Yeates, T.P.T., White, C., Marshall, A.H., Prewer, W. and Carlile, E. (2003) Bulked segregant AFLP analysis to identify markers for the introduction of the rhizomatous habit from Trifolium ambiguum into T. repens (white clover). Euphytica 134, 217-222.
Marshall, A. H., Williams, A., Abberton, M. T., Michaelson- Yeates, T. P. T., Powell, H. G. (2003) Dry matter production of white clover ( Trifolium repens L.), Caucasian clover ( T. ambiguum M. Bieb.) and their associated hybrids when grown with a grass companion over 3 harvest years Grass and Forage Science 58 (1), 63-69.
T.A. Williams and M.T. Abberton (2004) Earlier flowering between 1962-2002 in agricultural varieties of white clover Oecologia 138, 122-126.Marshall, A.H. Williams, T. A., Abberton, M. T., Michaelson-Yeates, T.P.T., Olyott, P., Powell, H. G. (2004) Forage quality of white clover ( Trifolium repens L.), Caucasian clover ( Trifolium ambiguum M. Bieb.) hybrids and their grass companion when grown over three harvest years Grass and Forage Science 59 (1), 91-99.Abberton, M.T. and Marshall, A. H. (2005) Progress in breeding perennial clovers for temperate agriculture Centenary Review Journal of Agricultural Science 143, 117-135.
Marshall , A.H. , Williams, T.A., Olyott, P., Abberton, M.T. and Michaelson-Yeates, T.P.T. (2005) Forage yield and persistency of Trifolium repens x Trifolium nigrescens hybrids under rotational sheep grazing Grass and Forage Science 60 (1), 68-73.
Cogan, N.O. I., Abberton, M. T., Smith, K.F., Kearney, G., Marshall, A.H., Williams, A., Michaelson Yeates, T.P.T. Bowen, C. , Jones, E.S., Vecchies, A.C. Forster J.W. (2006) Individual and multi-environment combined analyses identify QTLs for morphogenetic and reproductive development traits in white clover (Trifolium repens L.). Theor Appl Genet published on line April 2006(DOI 10.1007/s00122-006-0241-2)112 (8) 1401-1415 Fothergill, M., Abberton, M. T., Collins, R. P., Michaelson-Yeates, T. P. T., Williams, T. A., Marshall, A. H. (2007) Breeding forage legumes for the less favoured areas Biodiversity Science and Management in press
Febrer, M.; Cheung, F., Town, C. D., Cannon. S. B., Young, N. D., Abberton, M. T. Jenkins, G. and Milbourne, D. (2007) Construction, characterisation and preliminary BAC-end sequencing analysis of a bacterial artificial chromosome library of white clover (Trifolium repens L. ) Genome in press
Abberton, M. T. (2007) A review of interspecific hybridisation in the genus Trifolium. Plant Breeding in press
Williams, T. A, M.T. Abberton, P. Olyott, K.A. Mizen and R. Cook (2007) Evaluation of the effects of resistance to stem nematode (Ditylenchus dipsaci) in white clover (Trifolium repens L.) under sheep grazing and cutting Plant Breeding in press
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SID 5 (Rev. 3/06) Page 22 of 22
