Condensed tannins (CTs) account for up to 20% of the dry matter in forage legumes used as ruminant feeds. Beneficial animal responses to CTs have included improved growth, milk and wool production, fertility, and reduced methane emissions and ammonia volatilization from dung or urine. Most important is the ability of such forages to combat the effects of gastrointestinal parasitic nematodes. Inconsistent animal responses to CTs were initially attributed to concentration in the diet, but recent research has highlighted the importance of their molecular structures, as well as concentration, and also the composition of the diet containing the CTs. The importance of CT structural traits cannot be underestimated. Interdisciplinary research is the key to unraveling the relationships between CT traits and bioactivities and will enable future on‐farm exploitation of these natural plant compounds. Research is also needed to provide plant breeders with guidelines and screening tools to optimize CT traits, in both the forage and the whole diet. In addition, improvements are needed in the competitiveness and agronomic traits of CT‐containing legumes and our understanding of options for their inclusion in ruminant diets. Farmers need varieties that are competitive in mixed swards and have predictable bioactivities. This review covers recent results from multidisciplinary research on sainfoin (Onobrychis Mill. spp.) and provides an overview of current developments with several other tanniniferous forages. Tannin chemistry is now being linked with agronomy, plant breeding, animal nutrition, and parasitology. The past decade has yielded considerable progress but also generated more questions—an enviable consequence of new knowledge!

BackgroundSainfoin is a perennial forage legume with beneficial properties for animal husbandry due to the presence of secondary metabolites. However, worldwide cultivation of sainfoin is marginal due to the lack of varieties with good agronomic performance, adapted to a broad range of environmental conditions. Little is known about the genetics of sainfoin and only few genetic markers are available to assist breeding and genetic investigations. The objective of this study was to develop a set of SSR markers useful for genetic studies in sainfoin and their characterization in diverse germplasm.ResultsA set of 400 SSR primer combinations were tested for amplification and their ability to detect polymorphisms in a set of 32 sainfoin individuals, representing distinct varieties or landraces. Alleles were scored for presence or absence and polymorphism information content of each SSR locus was calculated with an adapted formula taking into account the tetraploid character of sainfoin. Relationships among individuals were visualized using cluster and principle components analysis. Of the 400 primer combinations tested, 101 reliably detected polymorphisms among the 32 sainfoin individuals. Among the 1154 alleles amplified 250 private alleles were observed. The number of alleles per locus ranged from 2 to 24 with an average of 11.4 alleles. The average polymorphism information content reached values of 0.14 to 0.36. The clustering of the 32 individuals suggested a separation into two groups depending on the origin of the accessions.ConclusionsThe SSR markers characterized and tested in this study provide a valuable tool to detect polymorphisms in sainfoin for future genetic studies and breeding programs. As a proof of concept, we showed that these markers can be used to separate sainfoin individuals based on their origin.Electronic supplementary materialThe online version of this article (doi:10.1186/s12863-016-0431-0) contains supplementary material, which is available to authorized users.

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ABSTRACT. Sainfoin (Onobrychis viciifolia) is a perennial forage legume with great potential for use in sustainable agriculture due to its low input requirements, good drought tolerance, and production of forage rich in polyphenolic compounds, which are beneficial for animal health. However, its distribution and cultivation are limited due to its moderate agronomic performance and a general lack of well adapted, highly yielding cultivars. Faster progress in breeding is imperative, but is often hampered by the complex inheritance of traits and limited knowledge on the genetic composition of this tetraploid, outbreeding species. Molecular genetic tools might aid phenotypic selection; however, to date no information on marker-trait associations is available for sainfoin. Hence, the goal of the present study was to detect marker- trait associations in a biparental F 1 population. Single plants were screened for recently developed genetic markers and phenotyped for important agronomic traits and concentrations of different polyphenolic compounds. Significant trait-associated markers (TAM) were detected for plant height (11), plant vigor (1), and seed yield (7). These three traits were positively correlated with each other and shared some TAMs. Correlations among markers suggested that two independent loci control these three vigor-related traits. One additional, independent TAM was detected for the share of prodelphinidins in total condensed tannins. Our results provide insight into the genetic control of important traits of sainfoin, and the TAMs reported here could assist selection in combination with phenotypic assessment.

BackgroundSainfoin (Onobrychis viciifolia) is a promising alternative forage plant of good quality, moderate nutrient demand and a high content of polyphenolic compounds. Its poor adoption is caused by the limited availability of well performing varieties. Sainfoin is characterised as tetraploid and mainly outcrossing, but the extent of self-fertilisation and its consequences was not investigated so far. This study aimed at assessing the rate of self-fertilisation in sainfoin under different pollination regimes and at analysing the consequences on plant performance in order to assist future breeding efforts.MethodsThe self-fertilisation rate was assessed in three sainfoin populations with artificially directed pollination (ADP) and in three populations with non-directed pollination (NDP). Dominant SRAP (sequence-related amplified polymorphism) and codominant SSR (simple sequence repeats) markers were used to detect self-fertilisation in sainfoin for the first time based on molecular marker data.ResultsHigh rates of self-fertilisation of up to 64.8 % were observed for ADP populations in contrast to only up to 3.9 % for NDP populations. Self-fertilisation in ADP populations led to a reduction in plant height, plant vigour and, most severely, for seed yield.ConclusionsAlthough sainfoin is predominantly outcrossing, self-fertilisation can occur to a high degree under conditions of limited pollen availability. These results will influence future breeding efforts because precautions have to be taken when crossing breeding material. The resulting inbreeding depression can lead to reduced performance in self-fertilised offspring. Nevertheless the possibility of self-fertilisation also offers new ways for hybrid breeding based on the development of homogenous inbred lines.Electronic supplementary materialThe online version of this article (doi:10.1186/s12863-015-0275-z) contains supplementary material, which is available to authorized users.

Cultivation of forage mixtures offers several advantages over monocultures, but forage legumes like alfalfa (Medicago sativa L.) are mostly bred in pure stands. Our goal was to assess the extent of accession-by-cultivation system interaction when alfalfa plants are grown in pure stands or in an easily adaptable nursery system together with their companion grasses, thereby determining the system most suitable for selection in mixture. Spaced plants of 50 alfalfa accessions were grown on bare soil as control treatment (CONV), in a sown sward of short growing lawn cultivars of tall fescue (Festuca arundinacea Schreb.) and red fescue (F. rubra L.) (LAWN), and in a sown sward of taller forage cultivars of the same species (FORA). Accession-by-cultivation system interaction variances were large for growth habit but small for vigor. Phenotypic correlation coefficients (rp) among the cultivation systems were high for vigor, whereby LAWN was somewhat more predictive for FORA (rp, FORA−LAWN = 0.83) than CONV (rp, FORA−CONV = 0.77). Observed accession-by-genotype interactions can be used pro or contra necessity for selection in mixture. However, the LAWN cultivation system might be a good compromise for practical breeding, allowing to account for given competition effects among species and to easily assess traits in the nursery.

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