Special Issue "Genetics and Breeding for Productivity Traits in Forage and Bioenergy Grasses"

A special issue of Agronomy (ISSN 2073-4395).

Deadline for manuscript submissions: closed (30 November 2016)

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A printed edition of this Special Issue is available here.

Special Issue Editors

Guest Editor
Prof. John W. Forster

Agriculture Victoria, AgriBio, the Centre for AgriBioscience, 5 Ring Road, Bundoora, Victoria 3083, Australia
Website | E-Mail
Phone: +61-3-9032-7054
Fax: +61-3 9032-7158
Interests: molecular genetics and genomics; genome architecture; quantitative trait loci; molecular breeding; forage grasses and legumes; forage grass endophytes; temperate grain legumes
Guest Editor
Prof. Kevin F. Smith

Professor of Pasture Agronomy (Plant Breeding), Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Private Bag 105, Hamilton, Victoria 3300, Australia
E-Mail
Phone: +61-3557-30951
Fax: +61-408-350-478
Interests: grass breeding; genetics and genomics; forage agronomy; molecular breeding; forage grasses and legumes; forage grass endophytes; economic analysis of forages.

Special Issue Information

Dear Colleagues,

Forage grasses provide the major components of pasture-based livestock production systems in temperate regions, and are also important for the feeding of animals in developing countries of the tropics and sub-tropics. Productivity traits for forage grasses include biomass, seasonality of yield, vegetative persistence, influence of flowering time, digestibility and nutritive quality. Traditionally, vegetative biomass yield has been the major breeding objective, but nutritive quality traits (such as content of sugars, proteins, and lipids) have become increasingly important. Accurate measurement of productivity characteristics has been difficult, limiting genetic gain in traditional breeding. The increasing availability of genomic and phenomic data for a range of forage grass species now allows characterization and selection at the individual plant level.

In parallel, a number of grass species (such as switchgrass and miscanthus) have been developed for bioenergy purposes, and productivity characteristics, including biomass delivery and biochemical content, are also critical for improvement of these crops. While some of these traits are shared priorities with forage grasses, others are of particular interest for bioenergy production. This increased specialization of grass cultivars creates both challenges and opportunities for grass breeders.

The aim of the Special Issue to provide a forum for contemporary studies of the genetics, genomics and phenomics of productivity traits in forage and bioenergy grasses, along with the application of such data to breeding practices and cultivar development. Original research articles and concepts for review articles to address major issues are welcome.

Prof. Dr. John W. Forster
Prof. Kevin F. Smith
Guest Editor

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Keywords

  • forage grass
  • bioenergy grass
  • biomass
  • seasonal yield
  • persistence
  • herbage digestibility
  • protein content
  • soluble carbohydrates
  • lignocellulosic content
  • biofermentation

Published Papers (15 papers)

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Research

Jump to: Review

Open AccessArticle Re-Programming Photosynthetic Cells of Perennial Ryegrass (Lolium perenne L) for Fructan Biosynthesis through Transgenic Expression of Fructan Biosynthetic Genes under the Control of Photosynthetic Promoters
Received: 16 February 2017 / Revised: 10 May 2017 / Accepted: 10 May 2017 / Published: 25 May 2017
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Abstract
High molecular weight fructans are the main class of water-soluble carbohydrate used for energy storage in many temperate grass species including perennial ryegrass (Lolium perenne L.). As well as being important readily mobilisable energy reserves for the plant, fructans are also involved [...] Read more.
High molecular weight fructans are the main class of water-soluble carbohydrate used for energy storage in many temperate grass species including perennial ryegrass (Lolium perenne L.). As well as being important readily mobilisable energy reserves for the plant, fructans are also involved in stress tolerance. Fructans are also readily digested by grazing ruminants and hence are a valuable source of energy for sheep, beef and dairy production systems in temperate regions. This paper describes the re-programming of the expression of fructan biosynthesis genes through the transgenic manipulation of 6-glucose fructosyltransferase (6G-FFT) and sucrose:sucrose 1-fructosyl-transferase (1-SST) in perennial ryegrass. Transgenic events were developed with altered fructan accumulation patterns with increases in fructan accumulation and greatly increased accumulation of fructan in leaf blades as opposed to the traditional site of fructan accumulation in the pseudostem. This altered site of fructan accumulation has potential benefits for animal production as leaf blades form the major part of the diet of grazing ruminants. Some of the transgenic events also exhibited enhanced biomass production. This combination of high quality and enhanced yield is of great interest to forage plant breeders and whilst the expression of these phenotypes needs to be confirmed under field conditions, the identification and characterisation of the transgenic events described in this paper validate the potential for the manipulation of fructan biosynthesis in perennial ryegrass. Full article
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Open AccessFeature PaperArticle Variation for Concentrations of Various Phytoestrogens and Agronomic Traits Among a Broad Range of Red Clover (Trifolium pratense) Cultivars and Accessions
Received: 15 September 2016 / Revised: 1 May 2017 / Accepted: 2 May 2017 / Published: 5 May 2017
Cited by 1 | PDF Full-text (571 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Agronomic characteristics and phytoestrogen concentrations were measured on 17 cultivars and 47 accessions of red clover (Trifolium pratense). These accessions included a range of currently recommended cultivars—from Australia and overseas—and germplasm accessed from genetic resource collections. All lines were grown in [...] Read more.
Agronomic characteristics and phytoestrogen concentrations were measured on 17 cultivars and 47 accessions of red clover (Trifolium pratense). These accessions included a range of currently recommended cultivars—from Australia and overseas—and germplasm accessed from genetic resource collections. All lines were grown in the field at Hamilton Vic in 2000 and 2001. Significant genetic variation was detected for key agronomic parameters such as growth habit, leaf shape and markings, leaf area, herbage yield, flowering time, and prolificacy. Significant variation in the concentration of the four main phytoestrogens was found; total isoflavone concentration ranged from 0.14–1.45% DM. Maximum concentrations of daidzein, genistein, formononetin, and biochanin were 0.06, 0.08, 0.86, and 0.91% DM respectively. Multivariate analysis showed that the accessions grouped into 10 distinct clusters that had between 1 and 10 members. Several accessions were superior to existing cultivars—notably Mediterranean accessions with regard to cool season vigour—and valuable for breeding programs to develop high yielding cultivars with either high (for possible medicinal purposes) or low (for grazing) phytoestrogen concentrations. Full article
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Open AccessArticle Molecular Characterizations of Kenyan Brachiaria Grass Ecotypes with Microsatellite (SSR) Markers
Received: 24 October 2016 / Accepted: 18 January 2017 / Published: 9 February 2017
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Abstract
Brachiaria grass is an emerging forage option for livestock production in Kenya. Kenya lies within the center of diversity for Brachiaria species, thus a high genetic variation in natural populations of Brachiaria is expected. Overgrazing and clearing of natural vegetation for crop production [...] Read more.
Brachiaria grass is an emerging forage option for livestock production in Kenya. Kenya lies within the center of diversity for Brachiaria species, thus a high genetic variation in natural populations of Brachiaria is expected. Overgrazing and clearing of natural vegetation for crop production and nonagricultural uses and climate change continue to threaten the natural biodiversity. In this study, we collected 79 Brachiaria ecotypes from different parts of Kenya and examined them for genetic variations and their relatedness with 8 commercial varieties. A total of 120 different alleles were detected by 22 markers in the 79 ecotypes. Markers were highly informative in differentiating ecotypes with average diversity and polymorphic information content of 0.623 and 0.583, respectively. Five subpopulations: International Livestock Research Institute (ILRI), Kitui, Kisii, Alupe, and Kiminini differed in sample size, number of alleles, number of private alleles, diversity index, and percentage polymorphic loci. The contribution of within‐the‐individual difference to total genetic variation of Kenyan ecotype population was 81%, and the fixation index (FST = 0.021) and number of migrant per generation (Nm = 11.58) showed low genetic differentiation among the populations. The genetic distance was highest between Alupe and Kisii populations (0.510) and the lowest between ILRI and Kiminini populations (0.307). The unweighted neighborjoining (NJ) tree showed test ecotypes grouped into three major clusters: ILRI ecotypes were present in all clusters; Kisii and Alupe ecotypes and improved varieties grouped in clusters I and II; and ecotypes from Kitui and Kiminini grouped in cluster I. This study confirms higher genetic diversity in Kenyan ecotypes than eight commercial varieties (Basilisk, Humidicola, Llanero, Marandú, MG4, Mulato II, Piatá and Xaraés) that represent three species and one three‐way cross‐hybrid Mulato II. There is a need for further collection of local ecotypes and their morphological, agronomical, and genetic characterizations to support Brachiaria grass breeding and conservation programs. Full article
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Open AccessArticle Development and Testing of Cool-Season Grass Species, Varieties and Hybrids for Biomass Feedstock Production in Western North America
Received: 29 September 2016 / Revised: 10 December 2016 / Accepted: 14 December 2016 / Published: 1 January 2017
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Abstract
Breeding of native cool-season grasses has the potential to improve forage production and expand the range of bioenergy feedstocks throughout western North America. Basin wildrye (Leymus cinereus) and creeping wildrye (Leymus triticoides) rank among the tallest and most rhizomatous [...] Read more.
Breeding of native cool-season grasses has the potential to improve forage production and expand the range of bioenergy feedstocks throughout western North America. Basin wildrye (Leymus cinereus) and creeping wildrye (Leymus triticoides) rank among the tallest and most rhizomatous grasses of this region, respectively. The objectives of this study were to develop interspecific creeping wildrye (CWR) × basin wildrye (BWR) hybrids and evaluate their biomass yield relative to tetraploid ‘Trailhead’, octoploid ‘Magnar’ and interploidy-hybrid ‘Continental’ BWR cultivars in comparison with other perennial grasses across diverse single-harvest dryland range sites and a two-harvest irrigated production system. Two half-sib hybrid populations were produced by harvesting seed from the tetraploid self-incompatible Acc:641.T CWR genet, which was clonally propagated by rhizomes into isolated hybridization blocks with two tetraploid BWR pollen parents: Acc:636 and ‘Trailhead’. Full-sib hybrid seed was also produced from a controlled cross of tetraploid ‘Rio’ CWR and ‘Trailhead’ BWR plants. In space-planted range plots, the ‘Rio’ CWR × ‘Trailhead’ BWR and Acc:641.T CWR × Acc:636 BWR hybrids displayed high-parent heterosis with 75% and 36% yield advantages, respectively, but the Acc:641.T CWR × ‘Trailhead’ BWR hybrid yielded significantly less than its BWR high-parent in this evaluation. Half-sib CWR × BWR hybrids of Acc:636 and ‘Trailhead’ both yielded as good as or better than available BWR cultivars, with yields similar to switchgrass (Panicum virgatum), in the irrigated sward plots. These results elucidate opportunity to harness genetic variation among native grass species for the development of forage and bioenergy feedstocks in western North America. Full article
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Open AccessArticle Variation and Correlations among European and North American Orchardgrass Germplasm for Herbage Yield and Nutritive Value
Received: 28 September 2016 / Revised: 16 November 2016 / Accepted: 16 November 2016 / Published: 2 December 2016
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Abstract
Efforts to improve water-soluble carbohydrate (WSC) concentrations are common in perennial forage grass breeding. Perennial ryegrass (Lolium perenne) breeding has been very successful in developing new cultivars with high WSC and high agronomic performance. Breeding efforts are ongoing to improve the [...] Read more.
Efforts to improve water-soluble carbohydrate (WSC) concentrations are common in perennial forage grass breeding. Perennial ryegrass (Lolium perenne) breeding has been very successful in developing new cultivars with high WSC and high agronomic performance. Breeding efforts are ongoing to improve the WSC of other perennial forage grasses, such as orchardgrass (Dactylis glomerata). The United States Department of Agriculture Forage and Range and Deutsche Saatveredelung orchardgrass breeding programs cooperated to characterize the expression and genotype by environment interaction (GEI) of water-soluble carbohydrates in a collection of orchardgrass populations from both breeding programs. Additionally, the effort characterized the relationship between water-soluble carbohydrates and other agronomic and nutritive value traits in these populations. Overall, the Deutsche Saatveredelung populations had higher herbage mass (15%), rust resistance (59%), and later maturity. The Forage and Range Research populations had higher water-soluble carbohydrates (4%), nutritive value, and earlier maturity. However, results were highly dependent on GEI. Differences were very pronounced at the French and German field locations, but less pronounced at the two US locations. Combining the germplasm from the Forage and Range Research and Deutsche Saatveredelung programs may be a way to develop an improved base germplasm source that could then be used separately in the EU and US for water-soluble carbohydrate and other trait improvement. Full article
Open AccessFeature PaperArticle Development of a Molecular Breeding Strategy for the Integration of Transgenic Traits in Outcrossing Perennial Grasses
Received: 29 September 2016 / Revised: 27 October 2016 / Accepted: 28 October 2016 / Published: 2 November 2016
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Abstract
Molecular breeding tools, such as genetic modification, provide forage plant breeders with the opportunity to incorporate high value traits into breeding programs which, in some cases, would not be available using any other methodology. Despite the potential impact of these traits, little work [...] Read more.
Molecular breeding tools, such as genetic modification, provide forage plant breeders with the opportunity to incorporate high value traits into breeding programs which, in some cases, would not be available using any other methodology. Despite the potential impact of these traits, little work has been published that seeks to optimize the strategies for transgenic breeding or incorporate transgenic breeding with other modern genomics-assisted breeding strategies. As the number of new genomics assisted breeding tools become available it is also likely that multiple tools may be used within the one breeding program. In this paper we propose a strategy for breeding genetically-modified forages using perennial ryegrass as an example and demonstrate how this strategy may be linked with other technologies, such as genomic selection. Whilst the model used is perennial ryegrass the principles outlined are valid for those designing breeding strategies for other outcrossing forage species. Full article
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Open AccessFeature PaperArticle Quantitative Trait Loci (QTL) Identification in the Progeny of a Polycross
Received: 23 September 2016 / Revised: 18 October 2016 / Accepted: 20 October 2016 / Published: 28 October 2016
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Abstract
Connected multiparental crosses are valuable for detecting quantitative trait loci (QTL) with multiple alleles. The objective of this study was to show that the progeny of a polycross can be considered as connected mutiparental crosses and used for QTL identification. This is particularly [...] Read more.
Connected multiparental crosses are valuable for detecting quantitative trait loci (QTL) with multiple alleles. The objective of this study was to show that the progeny of a polycross can be considered as connected mutiparental crosses and used for QTL identification. This is particularly relevant in outbreeding species showing strong inbreeding depression and for which synthetic varieties are created. A total of 191 genotypes from a polycross with six parents were phenotyped for plant height (PH) and plant growth rate (PGR) and genotyped with 82 codominant markers. Markers allowed the identification of the male parent for each sibling and so the 191 genotypes were divided into 15 full-sib families. The number of genotypes per full-sib family varied from 2 to 28. A consensus map of 491 cM was built and QTL were detected with MCQTL-software dedicated to QTL detection in connected mapping populations. Two major QTL for PH and PGR in spring were identified on linkage groups 3 and 4. These explained from 12% to 22% of phenotypic variance. The additive effects reached 12.4 mm for PH and 0.11 mm/C°d for PGR. This study shows that the progenies of polycrosses can be used to detect QTL. Full article
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Open AccessArticle Evidence for Heterosis in Italian Ryegrass (Lolium multiflorum Lam.) Based on Inbreeding Depression in F2 Generation Offspring from Biparental Crosses
Received: 14 September 2016 / Revised: 25 October 2016 / Accepted: 25 October 2016 / Published: 27 October 2016
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Abstract
Italian ryegrass is one of the most important temperate forage grasses on a global basis. Improvement of both dry matter yield and quality of herbage have been major objectives of pasture grass breeding over the last century. F1 and F2 progeny [...] Read more.
Italian ryegrass is one of the most important temperate forage grasses on a global basis. Improvement of both dry matter yield and quality of herbage have been major objectives of pasture grass breeding over the last century. F1 and F2 progeny sets derived from controlled pair-crosses between selected Italian ryegrass genotypes have been evaluated for yield and nutritive quality under field conditions. Linear regression of the performance of F1 families under sward conditions on parental genotype means in a spaced plant trial was significant for quality characteristics, but not for herbage yield. This result suggests that phenotypic selection of individual plants from spaced plant nursery is feasible for improvement of nutritive quality traits, but not for yield. The presence of significant heterosis within F1 populations was demonstrated by reduced herbage production in subsequent F2 populations (generated by one cycle of full-sib mating), an up to 22.1% total herbage yield in fresh weight, and a 30.5% survival rate at the end of the second reproductive cycle. Potential optimal crosses for exploiting such heterosis are discussed, based on construction and the inter-mating of complementary parental pools, for the implementation of a novel F1 hybrid production strategy. Full article
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Review

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Open AccessReview Opportunities for Napier Grass (Pennisetum purpureum) Improvement Using Molecular Genetics
Received: 28 February 2017 / Revised: 28 March 2017 / Accepted: 4 April 2017 / Published: 13 April 2017
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Abstract
Napier grass (Pennisetum purpureum Schumach.) is a fast-growing perennial grass native to Sub-Saharan Africa that is widely grown across the tropical and subtropical regions of the world. It is a multipurpose forage crop, primarily used to feed cattle in cut and carry [...] Read more.
Napier grass (Pennisetum purpureum Schumach.) is a fast-growing perennial grass native to Sub-Saharan Africa that is widely grown across the tropical and subtropical regions of the world. It is a multipurpose forage crop, primarily used to feed cattle in cut and carry feeding systems. Characterization and diversity studies on a small collection of Napier grasses have identified a moderate level of genetic variation and highlighted the availability of some good agronomic traits, particularly high biomass production, as a forage crop. However, very little information exists on precise phenotyping, genotyping and the application of molecular technologies to Napier grass improvement using modern genomic tools which have been applied in advancing the selection and breeding of important food crops. In this review paper, existing information on genetic resources, molecular diversity, yield and nutritional quality of Napier grass will be discussed. Recent findings on characterizing disease resistance and abiotic stress (drought) tolerance will also be highlighted. Finally, opportunities and future prospects for better conservation and use arising from the application of modern genomic tools in Napier grass phenotyping and genotyping will be discussed. Full article
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Open AccessReview Optimal Regulation of the Balance between Productivity and Overwintering of Perennial Grasses in a Warmer Climate
Received: 2 January 2017 / Revised: 17 February 2017 / Accepted: 21 February 2017 / Published: 23 February 2017
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Abstract
Seasonal growth patterns of perennial plants are linked to patterns of acclimation and de-acclimation to seasonal stresses. The timing of cold acclimation (development of freezing resistance) and leaf growth cessation in autumn, and the timing of de-acclimation and leaf regrowth in spring, is [...] Read more.
Seasonal growth patterns of perennial plants are linked to patterns of acclimation and de-acclimation to seasonal stresses. The timing of cold acclimation (development of freezing resistance) and leaf growth cessation in autumn, and the timing of de-acclimation and leaf regrowth in spring, is regulated by seasonal cues in the environment, mainly temperature and light factors. Warming will lead to new combinations of these cues in autumn and spring. Extended thermal growing seasons offer a possibility for obtaining increased yields of perennial grasses at high latitudes. Increased productivity in the autumn may not be possible in all high latitude regions due to the need for light during cold acclimation and the need for accumulating a carbohydrate storage prior to winter. There is more potential for increased yields in spring due to the availability of light, but higher probability of freezing events in earlier springs would necessitate a delay of de-acclimation, or an ability to rapidly re-acclimate. In order to optimize the balance between productivity and overwintering in the future, the regulation of growth and acclimation processes may have to be modified. Here, the current knowledge on the coordinated regulation of growth and freezing resistance in perennial grasses is reviewed. Full article
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Open AccessReview Molecular Regulation of Flowering Time in Grasses
Received: 29 November 2016 / Revised: 11 February 2017 / Accepted: 13 February 2017 / Published: 20 February 2017
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Abstract
Flowering time is a key target trait for extending the vegetative phase to increase biomass in bioenergy crops such as perennial C4 grasses. Molecular genetic studies allow the identification of genes involved in the control of flowering in different species. Some regulatory [...] Read more.
Flowering time is a key target trait for extending the vegetative phase to increase biomass in bioenergy crops such as perennial C4 grasses. Molecular genetic studies allow the identification of genes involved in the control of flowering in different species. Some regulatory factors of the Arabidopsis pathway are conserved in other plant species such as grasses. However, differences in the function of particular genes confer specific responses to flowering. One of the major pathways is photoperiod regulation, based on the interaction of the circadian clock and environmental light signals. Depending on their requirements for day-length plants can be classified as long-day (LD), short-day (SD), and day-neutral. The CONSTANS (CO) and Heading Date 1 (Hd1), orthologos genes, are central regulators in the flowering of Arabidopsis and rice, LD and SD plants, respectively. Additionally, Early heading date 1 (Ehd1) induces the expression of Heading date 3a (Hd3a), conferring SD promotion and controls Rice Flowering Locus T 1 (RFT1) in LD conditions, independently of Hd1. Nevertheless, the mechanisms promoting flowering in perennial bioenergy crops are poorly understood. Recent progress on the regulatory network of important gramineous crops and components involved in flowering control will be discussed. Full article
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Open AccessReview Diurnal Leaf Starch Content: An Orphan Trait in Forage Legumes
Received: 30 November 2016 / Revised: 2 February 2017 / Accepted: 6 February 2017 / Published: 20 February 2017
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Abstract
Forage legumes have a relatively high biomass yield and crude protein content, but their grazed and harvested biomass lacks the high-energy carbohydrates required to meet the productivity potential of modern livestock breeds. Because of their low carbohydrate content, forage legume diets are typically [...] Read more.
Forage legumes have a relatively high biomass yield and crude protein content, but their grazed and harvested biomass lacks the high-energy carbohydrates required to meet the productivity potential of modern livestock breeds. Because of their low carbohydrate content, forage legume diets are typically supplemented with starch rich cereal grains or maize (Zea mays), leading to the disruption of local nutrient cycles. Although plant leaves were first reported to accumulate starch in a diurnal pattern over a century ago, leaf starch content has yet to be exploited as an agronomic trait in forage crops. Forage legumes such as red clover (Trifolium pratense) have the genetic potential to accumulate up to one third of their leaf dry mass as starch, but this starch is typically degraded at night to support nighttime growth and respiration. Even when diurnal accumulation is considered with regard to the time the crop is harvested, only limited gains are realized due to environmental effects and post-harvest losses from respiration. Here we present original data for starch metabolism in red clover and place it in the broader context of other forage legumes such as, white clover (T. repens), and alfalfa (Medicago sativa). We review the application of recent advances in molecular breeding, plant biology, and crop phenotyping, to forage legumes to improve and exploit a potentially valuable trait for sustainable ruminant livestock production. Full article
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Open AccessReview The Current Status, Problems, and Prospects of Alfalfa (Medicago sativa L.) Breeding in China
Received: 23 September 2016 / Revised: 3 November 2016 / Accepted: 3 November 2016 / Published: 1 January 2017
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Abstract
This paper reviews the current status, methodology, achievements, and prospects of alfalfa (Medicago sativa L.) breeding in China. There are 77 cultivars that have been registered in the country, these include 36 cultivars bred through breeding programs, 17 introduced from overseas, 5 [...] Read more.
This paper reviews the current status, methodology, achievements, and prospects of alfalfa (Medicago sativa L.) breeding in China. There are 77 cultivars that have been registered in the country, these include 36 cultivars bred through breeding programs, 17 introduced from overseas, 5 domesticated from wild ecotypes, and 19 through regional collection/breeding programs. Cultivars have been selected for cold resistance, disease resistance, salt tolerance, grazing tolerance, high yield, and early maturity. Most of these cultivars have been developed through conventional breeding techniques, such as selective and cross breeding, and some are now being evaluated that have been developed through the application of transgenic technology. The major problems for alfalfa breeding in China include low success rate, slow progress to breed resistant varieties, lack of breeding materials and their systematic collection, storage and evaluation, lack of advanced breeding techniques, and low adoption rate of new cultivars. There are gaps in alfalfa breeding between China and the developed world. Improvement of alfalfa breeding techniques, development of cultivars with adaptations to different regions within China, and the protection and utilization of alfalfa germplasm resources have been identified as major strategies to improve the efficiency of alfalfa breeding in China. Full article
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Open AccessReview Haploid and Doubled Haploid Techniques in Perennial Ryegrass (Lolium perenne L.) to Advance Research and Breeding
Received: 28 September 2016 / Revised: 9 November 2016 / Accepted: 10 November 2016 / Published: 28 November 2016
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Abstract
The importance of haploid and doubled haploid (DH) techniques for basic and applied research, as well as to improve the speed of genetic gain when applied in breeding programs, cannot be overstated. They have become routine tools in several major crop species, such [...] Read more.
The importance of haploid and doubled haploid (DH) techniques for basic and applied research, as well as to improve the speed of genetic gain when applied in breeding programs, cannot be overstated. They have become routine tools in several major crop species, such as maize (Zea mays L.), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.). DH techniques in perennial ryegrass (Lolium perenne L.), an important forage species, have advanced to a sufficiently successful and promising stage to merit an exploration of what their further developments may bring. The exploitation of both in vitro and in vivo haploid and DH methods to (1) purge deleterious alleles from germplasm intended for breeding; (2) develop mapping populations for genetic and genomic studies; (3) simplify haplotype mapping; (4) fix transgenes and mutations for functional gene validation and molecular breeding; and (5) hybrid cultivar development are discussed. Even with the comparatively modest budgets of those active in forage crop improvement, haploid and DH techniques can be developed into powerful tools to achieve the acceleration of the speed of genetic gain needed to meet future agricultural demands. Full article
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Open AccessReview Considerations for Managing Agricultural Co-Existence between Transgenic and Non-Transgenic Cultivars of Outcrossing Perennial Forage Plants in Dairy Pastures
Received: 28 September 2016 / Revised: 3 November 2016 / Accepted: 10 November 2016 / Published: 25 November 2016
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Abstract
Many of the major forage species used in agriculture are outcrossing and rely on the exchange of pollen between individuals for reproduction; this includes the major species used for dairy production in grazing systems: perennial ryegrass (Lolium perenne L.) and white clover [...] Read more.
Many of the major forage species used in agriculture are outcrossing and rely on the exchange of pollen between individuals for reproduction; this includes the major species used for dairy production in grazing systems: perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.). Cultivars of these species have been co-existing since contrasting cultivars were developed using plant breeding, but the consequences and need for strategies to manage co-existence have been made more prominent with the advent of genetic modification. Recent technological developments have seen the experimental evaluation of genetically modified (GM) white clover and perennial ryegrass, although there is no current commercial growing of GM cultivars of these species. Co-existence frameworks already exist for two major cross-pollinated grain crops (canola and maize) in Europe, and for alfalfa (Medicago sativa L.) in the US, so many of the principles that the industry has developed for co-existence in these crops such as detection techniques, segregation, and agronomic management provide lessons and guidelines for outcrossing forage species, that are discussed in this paper. Full article
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