Unlocking the molecular basis of wheat straw composition and morphological traits through multi-locus GWAS.

BACKGROUND: Rapid reductions in emissions from fossil fuel burning are needed to curb global climate change. Biofuel production from crop residues can contribute to reducing the energy crisis and environmental deterioration. Wheat is a renewable source for biofuels owing to the low cost and high availability of its residues. Thus, identifying candidate genes controlling these traits is pivotal for efficient biofuel production. Here, six multi-locus genome-wide association (ML-GWAS) models were applied using 185 tetraploid wheat accessions to detect quantitative trait nucleotides (QTNs) for fifteen traits associated with biomass composition. RESULTS: Among the 470 QTNs, only 72 identified by at least two models were considered as reliable. Among these latter, 16 also showed a significant effect on the corresponding trait (p.value < 0.05). Candidate genes survey carried out within 4 Mb flanking the QTNs, revealed putative biological functions associated with lipid transfer and metabolism, cell wall modifications, cell cycle, and photosynthesis. Four genes encoded as Cellulose Synthase (CeSa), Anaphase promoting complex (APC/C), Glucoronoxylan 4-O Methyltransferase (GXM) and HYPONASTIC LEAVES1 (HYL1) might be responsible for an increase in cellulose, and natural and acid detergent fiber (NDF and ADF) content in tetraploid wheat. In addition, the SNP marker RFL_Contig3228_2154 associated with the variation in stem solidness (Q.Scsb-3B) was validated through two molecular methods (High resolution melting; HRM and RNase H2-dependent PCR; rhAMP). CONCLUSIONS: The study provides new insights into the genetic basis of biomass composition traits on tetraploid wheat. The application of six ML-GWAS models on a panel of diverse wheat genotypes represents an efficient approach to dissect complex traits with low heritability such as wheat straw composition. The discovery of genes/genomic regions associated with biomass production and straw quality parameters is expected to accelerate the development of high-yielding wheat varieties useful for biofuel production.

Klason lignin is a nutritionally heterogeneous fraction unsuitable for the prediction of forage neutral-detergent fibre digestibility in ruminants.

Although lignin has been negatively correlated with neutral-detergent fibre (NDF) digestibility (NDFD) in ruminants and used to predict potential extent of NDF digestion of forages, selection of an analysis, Klason lignin (KL) or acid-detergent lignin (ADL), to describe that the nutritionally relevant lignin has not been resolved. Dismissed as an artifact is the difference between KL and ADL (ΔL). A question is whether ΔL influences NDFD. We evaluated the relationships of ΔL, KL and ADL with NDFD in order to determine the nutritionally homogeneous or heterogeneous nature of KL. Data sets from two laboratories (DS1 and DS2) were used that included ADL, KL and in vitro NDFD at 48 h (NDFD48). DS1 contained seven C3 grasses, seventeen C4 maize forages and nineteen alfalfas, and DS2 had fifteen C3 grasses, eight C4 forages and six alfalfas. Mean ΔL was greater than ADL in C3 and C4 samples and less in alfalfas. Within forage type and laboratory, ΔL was not correlated with NDFD48 (r -0·34-0·49; all P > 0·17). ADL was more consistently correlated with NDFD48 (r -0·47--0·95; P < 0·01-0·21) than with KL (r 0·03--0·91; P < 0·01-0·94). ΔL as a proportion of KL was correlated with NDFD48 in C3 and C4 samples (r 0·44-0·76; P < 0·01-0·08). The differing behaviours of ΔL and ADL relative to NDFD48 indicate that KL is a nutritionally heterogeneous fraction, the behaviour of which may vary by forage type and ratios of ADL and ΔL present.

Evaluation and mining the applicable methods of roughage digestibility determination for buffalo (Bubalus bubalis).

Buffalo is an amazing ruminant with high tolerance to low-quality roughage. Due to the special breeding environment, there are few reports on the digestibility of roughage in buffalo because it is difficult to quantify ingestion and egestion. To find more applicable method to determine the digestibility of low-quality roughage in buffalo, this study was conducted to compare total feces collection (TFC) method with the following three indirect techniques: Cr2O3 (chromic oxide), AIA (acid-insoluble ash), and ADL (acid detergent lignin), to determine rice straw digestibility in buffalo. Six non-pregnant, non-lactating female buffaloes were used in this experiment and the nutritional compositions of the rice straw and feces were measured. Using Cr2O3 and AIA methods, the digestibility of dry matter (DM), ash, organic matter (OM), nitrogen free extract (NFE), crude protein (CP), ether extract (EE), crude fiber (CF), neutral detergent fiber (NDF), acid detergent fiber (ADF), cellulose (CEL), hemicellulose (HC), and ADL did not have statistically significant differences compared with TFC (P > 0.05). However, the digestibility of DM, ash, OM, NFE, EE, CF, NDF, ADF, and ADL determined using ADL method were significantly lower than those using the TFC (P < 0.05). The feces recovery of Cr2O3 and AIA was 95.89% and 97.14%, which were higher than that of ADL (88.90%). In summary, compare with ADL method, TFC, Cr2O3, and AIA methods are more accurate to determine the roughage digestibility of buffalo. Furthermore, Cr2O3 and AIA methods are applicable and convenient to evaluate the roughage digestibility of buffalo under extensive feeding system.

New methods for high-accuracy insect chitin measurement.

BACKGROUND: There is a growing interest in the use of insects in poultry, swine and aquaculture feed, as well as pet food applications. All insects produce chitin-based exoskeletons. With regard to chitin content, a precise determination in agricultural applications is crucial because it has favorable functional properties, although it is also difficult to digest for some species of livestock. Three measurement methods were compared to determine the most reliable method of chitin content determination in different insects and selected Hermetia illucens products: acid detergent fiber (ADF) provides the fiber content and the acid detergent lignin (ADL) additionally considers the catecholic compounds. Acetyl group measurement relates the acetate content to the chitin content. RESULTS: Comparing different insect species, the highest chitin value via ADF measurement was determined for the Tenebrio molitor larvae (155 g kg-1 ). Chitin values higher than 200 g kg-1 revealed that H. illucens residues are a much better valuable source of chitin. For the larval exoskeletons, a chitin content for all measurement methods of more than 350 g kg-1 was determined. In general, the ADF measurement is approximately 5% higher than the ADF-ADL and acetyl measurements. ADF-ADL and acetyl group determinations are approximately equivalent measurement methods. CONCLUSION: According to statistical analysis, ADF-ADL represents a compromise between accuracy and equipment demand and is a suitable method for determining the chitin content of both insects and their residues. © 2018 Society of Chemical Industry.

Acid detergent lignin, lodging resistance index, and expression of the caffeic acid O-methyltransferase gene in brown midrib-12 sudangrass.

Understanding the relationship between acid detergent lignin (ADL) and lodging resistance index (LRI) is essential for breeding new varieties of brown midrib (bmr) sudangrass (Sorghum sudanense (Piper) Stapf.). In this study, bmr-12 near isogenic lines and their wild-types obtained by back cross breeding were used to compare relevant forage yield and quality traits, and to analyze expression of the caffeic acid O-methyltransferase (COMT) gene using quantitative real time-PCR. The research showed that the mean ADL content of bmr-12 mutants (20.94 g kg(-1)) was significantly (P < 0.05) lower than measured in N-12 lines (43.45 g kg(-1)), whereas the LRI of bmr-12 mutants (0.29) was significantly (P < 0.05) higher than in N-12 lines (0.22). There was no significant correlation between the two indexes in bmr-12 materials (r = -0.44, P > 0.05). Sequence comparison of the COMT gene revealed two point mutations present in bmr-12 but not in the wild-type, the second mutation changed amino acid 129 of the protein from Gln (CAG) to a stop codon (UAG). The relative expression level of COMT gene was significantly reduced, which likely led to the decreased ADL content observed in the bmr-12 mutant.

Effects of Lablab purpurues and concentrate mixed supplements on reproductive performance and pre-weaning growth of Horro sheep grazing natural pasture in Ethiopia.

The goal of this study was to compare the productivity and reproduction of Horro ewes treated with concentrate supplements (T1), and Gebis-17 (T2) and Beresa-55 (T3) Lablab purpurues varieties. Horro ewes (n = 21, 7 ewes per treatment) with a mean premating weight of 26.3 + 2.1 kg (Mean + SD) were employed in the study. Ewes with uniform parity were selected from the Bako Agricultural Research Center sheep breeding flock. They were then blocked based on the premating weight into seven groups of three ewes each, and within each group randomly allocated to one of the three dietary treatments assigning seven ewes per treatment. Over an 8-month period, the ewes were supplemented with respective feed regimens, which encompassed 5 months of gestation and 3 months of lamb growth up to weaning. The results showed that supplementation enhanced lamb birth weight (3.01 vs. 3.42 vs. 3.42 kg) and ewe weight gain during pregnancy (76.94 vs. 42.11 vs. 58.05 g/day) for T1, T2, and T3, respectively as well as all reproductive features studied, except for abortion instances that occurred in ewes fed a diet in T2 and T3. The causes of abortion in T2 and T3 cannot be ascertained because the experimental ewes were grazing during the day. Even though the T1 diet improved ewe performance in a similar way to T3 and T2, the use of such supplements is usually limited due to their high cost and inaccessibility to smallholder farmers. This emphasizes the importance of seizing the chance to replace conventional protein supplements with low-cost, on-farm cultivated forage legumes like the one studied in this study. As a result, enhancing Horro ewes' performance with either T2 (Gebisa-17) or T3 (Beresa-55) diets throughout their mating season is a promising strategy for maximizing their genetic potential. Future research should focus on the effect of supplements on lambs' post-weaning growth rate and survival.

Effects of neutral detergent fiber digestibility estimation method on calculated energy concentration of canola meals from 12 Canadian processing plants.

Our aim was to determine whether the method used to estimate truly digestible neutral detergent fiber (tdNDF) affects calculated concentrations of total digestible nutrients (TDN1x) and net energy of lactation (NEL3x) of canola meal (CM). Samples were collected from 12 CM processing plants in Canada over 4 yr (2011 to 2014, n = 47) and analyzed for dry matter (DM), crude protein (CP), ether extract (EE), ash, neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin (ADL), and neutral detergent insoluble CP (NDICP). Ruminal in situ incubation of CM samples was performed at 0, 24, 48, 96, and 288 h to determine NDF fractions (A, B, and C), effective ruminal NDF digestibility (ERNDFD), and indigestible NDF (iNDF) of CM. Three tdNDF-estimation methods were evaluated: 1) National Research Council (NRC) = 0.75 × (NDF - NDICP - ADL) × {1- [ADL/ (NDF - NDICP)]0.667}; 2) iNDF = 0.75 × (NDF - NDICP - NDF remaining after 288 h in situ); and 3) ERNDFD estimated from in situ NDF digestion kinetics. Resulting tdNDF values were used for calculation of TDN1x and NEL3x according to NRC (2001) equations. Data were analyzed with MIXED procedure of SAS 9.4 to determine the effect of processing plant on chemical composition, NDF degradation kinetics and NEL3x of CM. Effect of tdNDF estimation method on calculated TDN1x and NEL3x of CM was also evaluated. Model for analysis of processing plant included the fixed effect of plant and the random effect of year (plant) as replication, while analysis of tdNDF methods included the fixed effect of tdNDF estimation method and the random effects of processing plant and of year(plant) as replication. There was an effect of processing plant on DM (P = 0.03), CP (P < 0.01), EE (P < 0.01), and NDF (P < 0.01) of CM. Processing plant also had an effect on NDF fractions A (P < 0.01) and B (P = 0.02) but did not affect fraction C and ERNDFD. The tdNDF estimation method had an effect on tdNDF (P < 0.01), TDN1x (P < 0.01), and NEL3x (P < 0.01) of CM, yielding average NEL3x values of 1.72, 1.87, and 2.07 Mcal/kg for NRC, iNDF, and ERNDFD, respectively. Our results indicate that calculated energy concentration of CM according to NRC (2001) equations varies depending on the method used for estimation of tdNDF. Further research will be needed to determine the most accurate estimation method.

Tensile strength of warm and cool season forage grasses in Florida.

The tensile strength (TS) of four warm-season and three cool-season forage grasses was measured with an Instron Universal machine, along with cell-wall analysis and determination of in vitro organic matter digestibility. The mean TS of the warm-season grasses was significantly higher than that of the cool season grasses (22 vs. 9 kg, respectively, p < .05). The concentrations of neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL) were significantly greater in the warm- than in the cool-season grasses (p < .05), whereas ash concentration was greater in the cool-season grasses. Among the warm-season grasses that were studied, elephant grass had the highest and bermuda grass had the lowest TS (34.4 and 14.9 kg, respectively, p < .05); Among the cool-season grasses triticale had greater TS than wheat and oats (12.6 vs. 6.8 and 7.5 kg, respectively, p < .05). TS was significantly correlated with NDF, ADF, and ADL, and negatively correlated with in vitro organic matter digestibility (correlation coefficients were 0.64, 0.73. 0.41, and -0.64, respectively). PRACTICAL APPLICATIONS: Grass tensile strength may have implications on animal preference and on the energy that animals must spend during grazing, and consequently on animal performance (feed intake, daily weight gain and milk, and meat production). Information on grass TS would help to select and screen improved forage cultivars and enable to improve grassland management with better animal performance.

Characterization of novel Sorghum brown midrib mutants from an EMS-mutagenized population.

Reducing lignin concentration in lignocellulosic biomass can increase forage digestibility for ruminant livestock and saccharification yields of biomass for bioenergy. In sorghum (Sorghum bicolor (L.) Moench) and several other C4 grasses, brown midrib (bmr) mutants have been shown to reduce lignin concentration. Putative bmr mutants isolated from an EMS-mutagenized population were characterized and classified based on their leaf midrib phenotype and allelism tests with the previously described sorghum bmr mutants bmr2, bmr6, and bmr12. These tests resulted in the identification of additional alleles of bmr2, bmr6, and bmr12, and, in addition, six bmr mutants were identified that were not allelic to these previously described loci. Further allelism testing among these six bmr mutants showed that they represented four novel bmr loci. Based on this study, the number of bmr loci uncovered in sorghum has doubled. The impact of these lines on agronomic traits and lignocellulosic composition was assessed in a 2-yr field study. Overall, most of the identified bmr lines showed reduced lignin concentration of their biomass relative to wild-type (WT). Effects of the six new bmr mutants on enzymatic saccharification of lignocellulosic materials were determined, but the amount of glucose released from the stover was similar to WT in all cases. Like bmr2, bmr6, and bmr12, these mutants may affect monolignol biosynthesis and may be useful for bioenergy and forage improvement when stacked together or in combination with the three previously described bmr alleles.

Energetic conversion of European semi-natural grassland silages through the integrated generation of solid fuel and biogas from biomass: energy yields and the fate of organic compounds.

Twelve European habitat types were investigated to determine the influence of the IFBB technique (integrated generation of biogas and solid fuel from biomass) on the fate of organic compounds and energy yields of semi-natural grassland biomass. Concentration of organic compounds in silage and IFBB press cake (PC), mass flows within that system and methane yields of IFBB press fluids (PF) were determined. The gross energy yield of the IFBB technique was calculated in comparison to hay combustion (HC) and whole crop digestion (WCD). The IFBB treatment increased fibre and organic matter (OM) concentrations and lowered non-fibre carbohydrates and crude protein concentrations. The PF was highly digestible irrespective of habitat types, showing mean methane yields between 312.1 and 405.0 LN CH4 kg(-1) VS. Gross energy yields for the IFBB system (9.75-30.19MWh ha(-1)) were in the range of HC, outperformed WCD and were influenced by the habitat type.