Water regimes in selected fodder radish (Raphanus sativus) genotypes: Effects on nutritional value and in vitro ruminal dry matter degradability.

Fodder radish is widely used as a livestock supplement, however, the nutritional value of fodder radish under different water conditions remains insufficiently understood. This study aimed to assess the chemical components and in vitro, ruminal dry matter degradability of two fodder radish genotypes (Endurance and Line 2) subjected to three irrigation regimes: well-watered (W1), moderate water stress (W2), and severe water stress (W3). The analysis revealed statistically significant effects of the main factors on the chemical composition and estimates of fodder radish leaves and tubers, particularly in terms of Crude Protein (CP) and Ether Extract (EE) across genotypes. Both Endurance and Line 2 leaves exhibited interaction effects on N, P, Ca, Mg, K, Na, Fe, Zn, Cu, Mn and Al. Meanwhile only Na, K, Zn, and Cu were affected in tubers. Endurance tubers, specifically, displayed significantly higher (p < 0.05) CP content, with Line 2 tubers showing the highest CP content under W1. Furthermore, Endurance leaves had higher levels of Neutral Detergent Fibre, EE, and Non-Structural Carbohydrate (NSC) compared to Line 2 leaves under W1. Notable differences in tuber fibres were found, specifically in Acid Detergent Fibre for Endurance, with W3 exhibiting a higher concentration level. Both genotypes displayed higher NSC under W3. Significant variations in macro and mmicro minerals were observed between water levels in both genotypes. In terms of in vitro degradability during the 24 h and 48 h incubation periods, all treatments met the acceptable level of 60-80 %. Regardless of water regimes, both Endurance and Line 2 showed nutrient concentrations meeting the minimum requirements for optimal animal production. Though, Line 2 exhibits significantly higher nutritional value and in vitro ruminal dry matter degradability than Endurance, evident in both leaves and tubers. Notably, moderate water stress conditions yielded better nutritional quality and in vitro ruminal dry matter degradability compared to both well-watered and severe water stress treatments. This suggests that applying 180-220 mm of water per season can also yield better nutritive value of these genotypes.

Multiple bHLH/MYB-based protein complexes regulate proanthocyanidin biosynthesis in the herbage of Lotus spp.

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.

Genomic Selection in Tropical Forage Grasses: Current Status and Future Applications.

The world population is expected to be larger and wealthier over the next few decades and will require more animal products, such as milk and beef. Tropical regions have great potential to meet this growing global demand, where pasturelands play a major role in supporting increased animal production. Better forage is required in consonance with improved sustainability as the planted area should not increase and larger areas cultivated with one or a few forage species should be avoided. Although, conventional tropical forage breeding has successfully released well-adapted and high-yielding cultivars over the last few decades, genetic gains from these programs have been low in view of the growing food demand worldwide. To guarantee their future impact on livestock production, breeding programs should leverage genotyping, phenotyping, and envirotyping strategies to increase genetic gains. Genomic selection (GS) and genome-wide association studies play a primary role in this process, with the advantage of increasing genetic gain due to greater selection accuracy, reduced cycle time, and increased number of individuals that can be evaluated. This strategy provides solutions to bottlenecks faced by conventional breeding methods, including long breeding cycles and difficulties to evaluate complex traits. Initial results from implementing GS in tropical forage grasses (TFGs) are promising with notable improvements over phenotypic selection alone. However, the practical impact of GS in TFG breeding programs remains unclear. The development of appropriately sized training populations is essential for the evaluation and validation of selection markers based on estimated breeding values. Large panels of single-nucleotide polymorphism markers in different tropical forage species are required for multiple application targets at a reduced cost. In this context, this review highlights the current challenges, achievements, availability, and development of genomic resources and statistical methods for the implementation of GS in TFGs. Additionally, the prediction accuracies from recent experiments and the potential to harness diversity from genebanks are discussed. Although, GS in TFGs is still incipient, the advances in genomic tools and statistical models will speed up its implementation in the foreseeable future. All TFG breeding programs should be prepared for these changes.

Analysis of the genitor origin of an intergeneric hybrid clone between Zea and Tripsacum for forage production by McGISH.

In this study, the chromosome number and composition of a novel perennial forage crop, 'Yucao No. 6' (Yu6), was revealed by chromosome spread and McGISH (multicolor genomic in situ hybridization) techniques to clarify its genitor origin. Cytogenetic analysis showed that Yu6, which has 56 chromosomes, is an aneuploid representing 12, 17 and 27 chromosomes from Zea mays ssp. mays L. (Zm, 2n = 2x = 20), Tripsacum dactyloides L. (Td, 2n = 4x = 72), and Z. perennis (Hitchc.) Reeves & Mangelsd. (Zp, 2n = 4x = 40), respectively. This finding indicates that Yu6 is the product of a reduced egg (n = 36 = 12Zm + 17Td + 7Zp) of MTP (a near-allohexaploid hybrid, 2n = 74 = 20Zm + 34Td + 20Zp) fertilized by a haploid sperm nucleus (n = 20Zp) of Z. perennis. Moreover, 3 translocated chromosomes consisting of the maize-genome chromosome with the segment of Z. perennis were observed. These results suggest that it is practical to develop perennial forage maize by remodeling the chromosomal architecture of MTP offspring with Z. perennis as a pollen parent. Finally, the overview of forage breeding in the Zea and Tripsacum genera was discussed.

Tripsazea, a Novel Trihybrid of Zea mays, Tripsacum dactyloides, and Zeaperennis.

A trispecific hybrid, MTP (hereafter called tripsazea), was developed from intergeneric crosses involving tetraploid Zea mays (2n = 4x = 40, genome: MMMM), tetraploid Tripsacum dactyloides (2n = 4x = 72, TTTT), and tetraploid Zperennis (2n = 4x = 40, PPPP). On crossing maize-Tripsacum (2n = 4x = 56, MMTT) with Zperennis, 37 progenies with varying chromosome numbers (36-74) were obtained, and a special one (i.e., tripsazea) possessing 2n = 74 chromosomes was generated. Tripsazea is perennial and expresses phenotypic characteristics affected by its progenitor parent. Flow cytometry analysis of tripsazea and its parents showed that tripsazea underwent DNA sequence elimination during allohexaploidization. Of all the chromosomes in diakinesis I, 18.42% participated in heterogenetic pairing, including 16.43% between the M- and P-genomes, 1.59% between the M- and T-genomes, and 0.39% in T- and P-genome pairing. Tripsazea is male sterile and partly female fertile. In comparison with previously synthesized trihybrids containing maize, Tripsacum and teosinte, tripsazea has a higher chromosome number, higher seed setting rate, and vegetative propagation ability of stand and stem. However, few trihybrids possess these valuable traits at the same time. The potential of tripsazea is discussed with respect to the deployment of the genetic bridge for maize improvement and forage breeding.

Genotypic Variation in a Breeding Population of Yellow Sweet Clover (Melilotus officinalis).

Yellow sweet clover is a widely spread legume species that has potential to be used as a forage crop in Western China. However, limited information is available on the genetic variation for herbage yield, key morphological traits, and coumarin content. In this study, 40 half sib (HS) families of M. officinalis were evaluated for genotypic variation and phenotypic and genotypic correlation for the traits: LS (leaf to stem ratio), SV (spring vigor), LA (leaf area), PH (plant height), DW (herbage dry weight), SD (stem diameter), SN (stem number), Cou (coumarin content), SY (seed yield), across two locations, Yuzhong and Linze, in Western China. There was significant (P < 0.05) genotypic variation among the HS families for all traits. There was also significant (P < 0.05) genotype-by-environment interaction for the traits DW, PH, SD, SN, and SV. The estimates of HS family mean repeatability across two locations ranged from 0.32 for SN to 0.89 for LA. Pattern analysis generated four HS family groups where group 3 consisted of families with above average expression for DW and below average expression for Cou. The breeding population developed by polycrossing the selected HS families within group 3 will provide a significant breeding pool for M. officinalis cultivar development in China.

Intra-inflorescence pollen viability in accessions of Brachiaria ruziziensis / Viabilidade de pólen intra-inflorescência em acessos de Brachiaria ruziziensis

Knowledge about the pollen viability is important to ensure success in controlled hybridizations and, consequently, support breeding programs. The aims of this study were to evaluate the pollen viability in progenies of artificially induced tetraploid accessions of Brachiaria ruziziensis, and to verify if the position of the flower buds on the raceme affects the pollen viability rate. Staining of aborted and non-aborted pollen (Alexander's technique) was used to determine the viability of the pollen grains. Tetraploid accessions of B. ruziziensis plants had high pollen viability (x = 76.8% to x = 99.6%). Some of these plants had viability rates similar to diploid B. ruziziensis, showing that the induction of chromosome duplication by colchicine did not result in abnormalities in production and morphology of pollen grains. Pollen grains from middle and apical regions of the raceme presented higher viability rates (x = 97.9% and x = 97.7% respectively). The viability of pollen grains in artificially induced tetraploid accessions of B. ruziziensis plants was high, which may favor obtaining fertile descendants in possible crosses.

O conhecimento da viabilidade de grãos de pólen é imprescindível para assegurar o sucesso nas hibridações controladas e, consequentemente, auxiliar programas de melhoramento genético. O objetivo deste estudo foi avaliar a viabilidade de grãos de pólen em progênies de Brachiaria ruziziensis tetraploidizadas artificialmente, além de verificar se há efeito da posição dos botões florais no racemo sobre a taxa de viabilidade de pólen. A coloração de pólen abortado e não abortado (técnica de Alexander) foi usado para determinar a viabilidade dos grãos de pólen. Plantas de B. ruziziensis apresentaram elevada viabilidade de pólen (x = 76,8% a x = 99,6%). Algumas dessas plantas apresentaram taxas de viabilidade similares a B. ruziziensis diploide, mostrando que a indução de duplicação cromossômica usando colchicina não resultou em anormalidades na produção e na morfologia dos grãos de pólen. Grãos de pólen das regiões mediana e apical do racemo apresentaram maiores taxas de viabilidade (x = 97,9% e x = 97,7%, respectivamente). A viabilidade dos grãos de pólen em plantas de Brachiaria ruziziensis tetraploidizadas artificialmente foi alta, o que pode favorecer a obtenção de descendentes férteis em eventuais cruzamentos.

Estacionalidade e estabilidade de produção de forragem de progênies de Brachiaraia ruziziensis / Seasonality and stability of forage production of Brachiaraia ruziziensis progenies

Conduziu-se este trabalho, com o objetivo de avaliar a produtividade de biomassa de forragem de progênies de Brachiaria ruziziensis e a estabilidade de produção ao longo de diferentes cortes, representativos de épocas favoráveis e desfavoráveis ao desenvolvimento das forrageiras. Foram avaliadas 118 progênies de B. ruziziensis, juntamente com as testemunhas B. decumbens cv. Basilisk, B. brizantha cv. Marandu, B. ruziziensis cv. Comum e Brachiaria sp., em delineamento de blocos casualisados, com duas repetições. Realizaram-se sete cortes de avaliação com intervalos médios de 60 e 90 dias nas épocas das águas (5 cortes) e das secas (2 cortes). Em cada um deles mensurou-se a altura das plantas (ALT) e as produtividades de biomassa de forragem verde (PBV) e seca (PBS). As médias dos diferentes cortes, nas épocas das águas ou das secas, foram utilizadas para a realização de análises de variância, em esquema fatorial (progênies x épocas), para a avaliação dos efeitos de estacionalidade de produção das progênies. Também foi realizada a avaliação da estabilidade das progênies. Apesar da grande concentração da PBV e PBS na época das águas, detectou-se a existência de variabilidade genética entre progênies de B. ruziziensis para ALT, PBV e PBS, tanto na época das águas como na seca. Alguns materiais avaliados apresentaram estabilidades de produção superiores às principais cultivares comerciais de Brachiaria, indicando ser possível a identificação e seleção de materiais de B. ruziziensis com médias mais elevadas e com produção mais estável ao longo do ano.

The objective of this study was to evaluate the forage biomass productivity of Brachiaria ruziziensis progenies and yield stability over different cuts, representing favorable and unfavorable periods of forage development. 118 progenies of B. ruziziensis and the controls B. decumbens cv. Basilisk, B. brizantha cv. Marandu, B. ruziziensis cv. Common and Brachiaria sp. were evaluated using a randomized block design with two replicates. There were seven cuts assessment with an average interval of 60 and 90 days in water (5 cuts) and dry (2 cuts) seasons. In each cut, plants height (ALT) and dry (PBS) and green (PBV) biomass forage yield were measured. The averages of the different cuts made in dry or water seasons were used to perform statistical analysis in a factorial (progeny x times) for the effects of progeny production seasonality. The stability analysis also was performed. Despite the large concentration of PBV and PBS in the rainy season, the existence of genetic variability between progenies of B. ruziziensis for ALT, PBV and PBS were observed in both rainy and dry seasons. Some evaluated materials showed production stabilities higher than commercial cultivars of Brachiaria indicating the possibility of identification and selection of B. ruziziensis material with higher average and stable production over the year.

Avaliação do potencial de propagação por sementes de capim-elefante hexaplóide / Evaluation of the potential of propagation by seed of hexaploid elephant-grass

O capim-elefante é uma das gramíneas de maior potencial para produção de leite e carne a pasto. Entretanto, a forma de multiplicação por estacas dificulta a sua maior expansão. O cruzamento interespecífico envolvendo o milheto visa, entre outras coisas, o aumento do tamanho das sementes facilitando a sua propagação. Objetivou-se no presente trabalho, verificar o potencial de germinação de sementes em diferentes progênies de capim-elefante hexaplóide para confirmação da viabilidade de propagação dessa forrageira, por meio de sementes. O experimento foi conduzido na Embrapa Gado de Leite e foram avaliadas 78 progênies de meio-irmãos de capim-elefante hexaplóide. Empregou-se o delineamento de blocos casualizados, com três repetições e parcelas de 100 sementes. Em cada parcela foram realizadas três contagens do número de sementes germinadas, em intervalos de sete dias, para obtenção da porcentagem de germinação das sementes. Observaram-se diferenças significativas entre os tratamentos evidenciando a existência de variabilidade no potencial de multiplicação por sementes das progênies de meio-irmãos de capim-elefante hexaplóide. A amplitude de variação para a porcentagem de germinação das sementes foi de 48,67 por cento. As médias das progênies foram divididas em seis grupos pelo teste de Scott-Knott e as progênies 64, 53, 19, 62, 2, 45, 72, 10 e 77 apresentaram melhor desempenho, com germinação das sementes superior a 35 por cento.

Elephant grass is a grass with one of the highest potential for milk and beef production under grazing conditions. However, its utilization is limited due to the dissemination method that uses stems for pasture formation. The interespecific cross with pearl-millet, aims to obtain seeds of bigger size to facilitate the propagation of elephant grass. The objective of this paper was to verify the germination potential of different progenies of elephant grass hexaploid seeds to confirm the viability of this dissemination method. The experiment was carried out at Embrapa Gado de Leite, evaluating 78 half-sib progenies of hexaploid elephant grass in a complete randomized block design with three replications and 100 seeds per experimental unit. Three counting of germinated seeds were done in each experimental unit every seven days. Significant differences were observed between progenies showing the existence of variability in the potential for the dissemination when using seeds originated from half-sib progenies of hexaploid elephant grass. The range of variation for seed germination was 48,67 percent. The progenies were divided into six groups by the Scott-Knott test and the progenies 64, 53, 19, 2, 45, 72, 10 and 77 presented the best germination rate, with values above 35 percent.