Application of Molecular Markers Derived from \u3cem\u3eMedicago Truncatula\u3c/em\u3e in White Clover (\u3cem\u3eTrifolium Repens\u3c/em\u3e L.)

White clover is the major forage legume of temperate areas. Genome maps have been produced recently (Jones et al., 2003; Barrett et al., 2004) and the location of QTL for important agricultural traits reported (Abberton et al., 2004). White clover is closely related to the model legume Medicago truncatula and there is likely to be considerable benefit in applying genomic resources from model to crop. However, the extent of synteny between the species must be established. Here we present preliminary results detailing progress towards this goal

Grass and Forage Improvement: Temperate Forages

Key points 1. Plant breeding has contributed significantly to the development of effective grassland production systems. 2. New technologies offer enhanced precision in breeding and access to wider genetic variation. 3. The requirement for more sustainable production systems will require genetic improvements in complex traits where the use of new technology will be vital

Deep sequencing of Suppression Subtractive Hybridisation drought and recovery libraries of the non-model crop Trifolium repens L.

Open Access Journal; Published online: 23 Feb. 2017White clover is a short-lived perennial whose persistence is greatly affected by abiotic stresses, particularly drought. The aim of this work was to characterize its molecular response to water deficit and recovery following re-hydration to identify targets for the breeding of tolerant varieties. We created a white clover reference transcriptome of 16,193 contigs by deep sequencing (mean base coverage 387x) four Suppression Subtractive Hybridization (SSH) libraries (a forward and a reverse library for each treatment) constructed from young leaf tissue of white clover at the onset of the response to drought and recovery. Reads from individual libraries were then mapped to the reference transcriptome and processed comparing expression level data. The pipeline generated four robust sets of transcripts induced and repressed in the leaves of plants subjected to water deficit stress (6,937 and 3,142, respectively) and following re-hydration (6,695 and 4,897, respectively). Semi-quantitative polymerase chain reaction was used to verify the expression pattern of 16 genes. The differentially expressed transcripts were functionally annotated and mapped to biological processes and pathways. In agreement with similar studies in other crops, the majority of transcripts up-regulated in response to drought belonged to metabolic processes, such as amino acid, carbohydrate, and lipid metabolism, while transcripts involved in photosynthesis, such as components of the photosystem and the biosynthesis of photosynthetic pigments, were up-regulated during recovery. The data also highlighted the role of raffinose family oligosaccharides (RFOs) and the possible delayed response of the flavonoid pathways in the initial response of white clover to water withdrawal. The work presented in this paper is to our knowledge the first large scale molecular analysis of the white clover response to drought stress and re-hydration. The data generated provide a valuable genomic resource for marker discovery and ultimately for the improvement of white clover

Changes in Gene Expression During Acclimation to Cold Temperatures in White Clover (\u3cem\u3eTrifolium Repens\u3c/em\u3e L.)

White clover is an important component of many temperate pastures and improved winter hardiness is a major objective of breeding programmes in many countries. Exposure to cold and fluctuations in temperature are components of winter stress and although some studies have investigated the agronomic and physiological mechanisms of cold tolerance, little research has been carried out to identify the genes involved. We are complementing mapping of quantitative trait loci (QTL) responsible for cold tolerance with studies of variation in gene expression between plants growing at different temperatures. In particular we are initially focusing on the process of acclimation by analysing plants subjected to low but above zero temperatures

Towards a Comparative Map of White Clover (Trifolium Repens) and Barrel Medic (Medicago Truncatula)

Grassland is of pivotal importance to the Irish agricultural industry. This dependence of grass is reflected in the large proportion of land area under grass, approx. 80% of the total land acreage in Ireland. The presence of white clover (Trifolium repens L.) in grassland significantly improves the overall nutritional value of the forage by increasing the relative amounts of nitrogen present. Genetic improvement of white clover through breeding of varieties should increase the productivity of grasslands. Advances in plant biotechnology offer the possibility of developing tools that will radically enhance our ability to breed improved plant varieties. The objective of this study is (1) to construct a genetic map of white clover and (2) to assess the level of genome synteny of white clover and M. truncatula (the model for legume species) with the use of different molecular markers developed in M. truncatula

Grass and Forage Improvement: Temperate Forages

Plant breeding has contributed significantly to the development of effective grassland production systems. New technologies offer enhanced precision in breeding and access to wider genetic variation. The requirement for more sustainable production systems will require genetic improvements in complex traits where the use of new technology will be vital

Breeding White Clover With Improved Tolerance of Nitrogen Fertiliser

White clover (Trifolium repens L.) is often considered a forage legume with a primary use in \u27low input/ low output\u27 systems. One facet of this is the perception that the persistency of this species is poor when Nitrogen (N) fertiliser is applied. However, new varieties of white clover are able to play a significant role in highly productive systems (Williams et al., 2000) and show consistent yields over ten years at a range of applied N levels (Williams et al., 2003). Germplasm improvement for nitrogen tolerance has been carried out with the aim of not only allowing white clover to perform well under applied N but also to dampen the oscillations in clover yield that may be a consequence of the build up of N fixed by the clover itself. The former aspect is illustrated in this paper with respect to the variety AberConcord

Deep sequencing of Suppression Subtractive Hybridisation drought and recovery libraries of the non-model crop Trifolium repens L.

Open Access Journal; Published online: 23 Feb. 2017White clover is a short-lived perennial whose persistence is greatly affected by abiotic stresses, particularly drought. The aim of this work was to characterize its molecular response to water deficit and recovery following re-hydration to identify targets for the breeding of tolerant varieties. We created a white clover reference transcriptome of 16,193 contigs by deep sequencing (mean base coverage 387x) four Suppression Subtractive Hybridization (SSH) libraries (a forward and a reverse library for each treatment) constructed from young leaf tissue of white clover at the onset of the response to drought and recovery. Reads from individual libraries were then mapped to the reference transcriptome and processed comparing expression level data. The pipeline generated four robust sets of transcripts induced and repressed in the leaves of plants subjected to water deficit stress (6,937 and 3,142, respectively) and following re-hydration (6,695 and 4,897, respectively). Semi-quantitative polymerase chain reaction was used to verify the expression pattern of 16 genes. The differentially expressed transcripts were functionally annotated and mapped to biological processes and pathways. In agreement with similar studies in other crops, the majority of transcripts up-regulated in response to drought belonged to metabolic processes, such as amino acid, carbohydrate, and lipid metabolism, while transcripts involved in photosynthesis, such as components of the photosystem and the biosynthesis of photosynthetic pigments, were up-regulated during recovery. The data also highlighted the role of raffinose family oligosaccharides (RFOs) and the possible delayed response of the flavonoid pathways in the initial response of white clover to water withdrawal. The work presented in this paper is to our knowledge the first large scale molecular analysis of the white clover response to drought stress and re-hydration. The data generated provide a valuable genomic resource for marker discovery and ultimately for the improvement of white clover.BBSRC Research GrantsPeer Revie

Root Senescence in Red Clover (\u3cem\u3eTrifolium Pratense\u3c/em\u3e L.)

Legume root systems form a mosaic of living, ageing and dead roots and nodules. The balance between these stages alters during plant development. Stressful events (drought, temperature change, reduced carbon supply, etc.) disturb the balance (Butler et al., 1959). Effects of root and nodule death on soil structure, composition and leaching and on plant persistency are understood poorly. Plants with differing senescence patterns are useful tools to study these effects. Molecular studies of root senescence need detailed knowledge of the process and timing of root senescence and death. Biochemical and histochemical markers of senescence were used to generate preliminary results of the effects of reduced carbon input, temporary (by defoliation, D) or permanent (by defoliation and shading, DS) on red clover shoot survival and root death