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Main conclusion: The complexes involving MYBPA2, TT2b, and TT8 proteins are the critical regulators of ANR and LAR genes to promote the biosynthesis of proanthocyanidins in the leaves of Lotus spp. The environmental impact and health of ruminants fed with forage legumes depend on the herbage's concentration and structure of proanthocyanidins (PAs). Unfortunately, the primary forage legumes (alfalfa and clover) do not contain substantial levels of PAs. No significant progress has been made to induce PAs to agronomically valuable levels in their edible organs by biotechnological approaches thus far. Building this trait requires a profound knowledge of PA regulators and their interplay in species naturally committed to accumulating these metabolites in the target organs. Against this background, we compared the shoot transcriptomes of two inter-fertile Lotus species, namely Lotus tenuis and Lotus corniculatus, polymorphic for this trait, to search for differentially expressed MYB and bHLH genes. We then tested the expression of the above-reported regulators in L. tenuis x L. corniculatus interspecific hybrids, several Lotus spp., and different L. corniculatus organs with contrasting PA levels. We identified a novel MYB activator and MYB-bHLH-based complexes that, when expressed in Nicotiana benthamiana, trans-activated the promoters of L. corniculatus anthocyanidin reductase and leucoanthocyanidin reductase 1 genes. The last are the two critical structural genes for the biosynthesis of PAs in Lotus spp. Competition between MYB activators for the transactivation of these promoters also emerged. Overall, by employing Lotus as a model genus, we refined the transcriptional network underlying PA biosynthesis in the herbage of legumes. These findings are crucial to engineering this trait in pasture legumes. [ABSTRACT FROM AUTHOR]

The genus Cynodon includes species that have huge potential to produce high-quality fodder, for grazing and hay production. In perennial forage breeding, selection should be performed based on repeated measurements in the same individual over time, which maximizes the selective efficiency. Thus, the objectives of this study were to estimate the coefficients of repeatability and optimal number of measures for the genetic selection of Cynodon spp. clones. We evaluated 202 clones, being five checks, during four harvests, in augmented block design. A mixed model methodology (REML/BLUP) was used to estimate the variance components and predict the genotypic values. The repeatability coefficient for plant height, green weight, dry matter, and plant vigor were equal to 0.50, 0.67, 0.25, and 0.73, respectively. The accuracies obtained by performing m repeated measures revealed that 5, 2, 13, and 2 measurements are required to attain an accuracy ≥ 90% in genetic gain from the selection for plant height, green weight, dry matter, and plant vigor, respectively. Furthermore, the efficiency of performing four measurements compared with that of performing only one measurement was 27%, 15%, 51%, and 12% for plant height, green weight, dry matter, and vigor, respectively. In addition, the additive index, adopting a 10% selection intensity, was used in simultaneous selection, leading to desirable genetic gains for plant height, green weight, and plant vigor. In conclusion, the use of the repeatability coefficient suggests performing three measurements to obtain a high accuracy and good efficiency on the selection of superior genotypes of Cynodon spp. [ABSTRACT FROM AUTHOR]

High fertilizer prices and improved environmental stewardship have increased interest in grasslegume mixed pastures. It has been hypothesized, but not validated, that the ecological combining ability between grasses and legumes can be improved by breeding specifically for mixture performance. This experiment examined the predicted efficiency of selection in a grass monoculture environment to indirectly improve tall fescue (Lolium arundinaceum(Schreb.) Darbysh.) forage mass in a grass-legume mixture. Heritability, genetic and rank correlations, and selection efficiencies were estimated for forage mass in a tall fescue half-sib population grown as spaced-plants over seeded with either turf-type tall fescue (monoculture) or alfalfa (mixture). Heritability for tall fescue forage mass in monoculture ranged from 0.32 to 0.70 and were always similar or greater than those in mixture (range 0.27- 0.55) for four successive harvests and annual total. Genetic correlations between monoculture and mixture tall fescue forage mass varied with values of 0.48, 0.92, -0.31, 0.70, and 0.25 in June, July, August, October, and annual total, respectively. Indirect selection efficiencies exceeded or approached direct selection for mixtures only in July and October (1.29, and 0.73, respectively). Whereas, indirect selection efficiencies were low in June, August, and annual forage mass (0.58, -0.31, and 0.28, respectively). Moreover, low Spearman’s rank correlations (-0.03 to 0.35) indicated differing half-sib family performance between the monoculture and mixture environments. Results indicate that direct selection should be used to improve tall fescue forage mass in a grass-legume mixture, and support the hypothesis of increasing ecological combining ability by breeding for mixtures per se. [ABSTRACT FROM AUTHOR]

The objectives of this study were to characterize crested wheatgrass (Agropyron cristatum L.) germplasm for plant maturity and associated agronomic characteristics to identify germplasm with late maturity. A field trial was established in July 2014 at Saskatoon, Canada using 45 crested wheatgrass accessions representing materials from 18 countries in a randomized complete block design with four replications. Data were collected for days to heading, plant height, leaf-to-stem ratio, forage dry matter (DM) yield, crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and plant vigor score in 2015, 2016 and 2017 at various developmental stages of crested wheatgrass. All measured traits differed significantly (P ≤ 0.05) among the accessions. Later maturing accessions showed positive associations with leaf-to-stem ratio (r = 0.23), NDF (r = 0.16) and ADF (r = 0.18). Forage DM yield was positively correlated with spring vigor (r = 0.77), leaf-to-stem ratio (r = 0.50), plant height (r = 0.56), regrowth (r = 0.67), and ADF (r = 0.11). There was a negative correlation between forage DM yield and CP concentration (r = − 0.23). According to the unweighted pair group method with arithmetic mean and principal component analysis, the 45 crested wheatgrass accessions were grouped into three main clusters according to the agro-morphological and nutritive value data. Selection for late maturity in crested wheatgrass may lead to increase leaf-to-stem ratio and forage DM yield. Information obtained from this study on agro-morphological traits will be useful for future crested wheatgrass breeding in the region. [ABSTRACT FROM AUTHOR]