Genome-wide association mapping of lentil (Lens culinaris Medikus) prebiotic carbohydrates toward improved human health and crop stress tolerance

Lentil, a cool-season food legume, is rich in protein and micronutrients with a range of prebiotic carbohydrates, such as raffinose-family oligosaccharides (RFOs), fructooligosaccharides (FOSs), sugar alcohols (SAs), and resistant starch (RS), which contribute to lentil's health benefits. Beneficial microorganisms ferment prebiotic carbohydrates in the colon, which impart health benefits to the consumer. In addition, these carbohydrates are vital to lentil plant health associated with carbon transport, storage, and abiotic stress tolerance. Thus, lentil prebiotic carbohydrates are a potential nutritional breeding target for increasing crop resilience to climate change with increased global nutritional security. This study phenotyped a total of 143 accessions for prebiotic carbohydrates. A genome-wide association study (GWAS) was then performed to identify associated variants and neighboring candidate genes. All carbohydrates analyzed had broad-sense heritability estimates (H2) ranging from 0.22 to 0.44, comparable to those reported in the literature. Concentration ranges corresponded to percent recommended daily allowances of 2-9% SAs, 7-31% RFOs, 51-111% RS, and 57-116% total prebiotic carbohydrates. Significant SNPs and associated genes were identified for numerous traits, including a galactosyltransferase (Lcu.2RBY.1g019390) known to aid in RFO synthesis. Further studies in multiple field locations are necessary. Yet, these findings suggest the potential for molecular-assisted breeding for prebiotic carbohydrates in lentil to support human health and crop resilience to increase global food security.

Estimation of the net energy value of barley for finishing beef steers

The objective of this study was to identify barley grain characteristics measured by laboratory procedures that could be used to predict barley energy content for finishing beef steers. Twenty-eight different barley genotypes were evaluated including 18 cultivars and 10 experimental lines. Laboratory analysis of barley samples included bulk density, particle size, N, ADF, starch, and ISDMD (in situ DM disappearance after 3 h of ruminal incubation). Animal performance data (BW, DMI, ADG, steer NE_m, and NE_g requirements) were collected from 26 feedlot experiments conducted in Montana and Idaho during a 10-yr period and were used to estimate barley NE_m and NE_g content. A total of 80 experimental units were available with each experimental unit being a diet mean from an individual feedlot experiment. Fifty-eight of the 80 experimental units were randomly selected and used in the development data set and the remaining 22 experimental units were used in the validation data set. Forward, backward, and stepwise selection methods were used to identify variables to be included in regression equations for NE_m using PROC REG of SAS. Barley samples in the model development data set represented a wide range in concentrations (DM basis): N (1.6% to 2.8%), ISDMD (25.7% to 58.7%), ADF (3.6% to 8.0%), starch (44.1% to 62.4%), particle size (1,100 to 2,814 µm), and bulk density (50.8 to 69.4 kg/hL). The barley grain characteristics of particle size, ISDMD, starch, and ADF were the most important variables in six successful models (R ² = 0.48 to 0.60; P = 0.001). The six prediction equations gave mean predicted values for NE_m ranging from 1.99 to 2.05 Mcal/kg (average 2.04 Mcal/kg; 0.45% CV). The mean actual NE_m values from animal performance trials ranged from 1.75 to 2.48 Mcal/kg (average 2.03 Mcal/kg; 6.5% CV). The mean bias or difference in predicted vs. actual values ranged from -0.001 to 0.005 Mcal/kg. Barley NE_g values calculated from animal performance ranged from 1.13 to 1.78 Mcal/kg (average 1.39 Mcal/kg; 8.4% CV). Average predicted barley NE_m and NE_g were 0.02 and 0.01 Mcal/kg less, respectively, than the 2.06 Mcal/kg NE_m and 1.40 Mcal/kg NE_g reported by NRC. Barley NE can be predicted from simple laboratory procedures which will aid plant breeders developing new feed varieties and nutritionists formulating finishing rations for beef cattle.

A regulator of early flowering in barley (Hordeum vulgare L.)

Heading date (HD) of cereals is an important trait for adaptation to diverse environments and is critical for determining yield and quality and the number of genes and gene combinations that confer earliness in barley under short days is limited. In our study, a QTL for early flowering was identified from the cross between an Australian malting barley cultivar and a Chinese landrace. Four sets of near isogenic lines (NILs) were developed with a QTL located on chromosome 5H at the interval of 122.0-129.0 cM. Further experiments were conducted to investigate how this gene was regulated by photoperiod using the NILs with three sowing dates from autumn to summer. The NILs carrying the earliness allele were significantly earlier than the late genotype at all sowing dates. This gene was different from previously reported vernalisation genes that are located at a similar position as no vernalisation was required for all the NILs. The difference between this gene and Eam5 (HvPHYC) locus which also located between two co-segregated markers (3398516S5, 122.5 cM, and 4014046D5, 126.1 cM), is that with the existence of Ppd-H1 (Eam1), Eam5 has no effect on ear emergence under long days while the gene from TX9425 still reduced the time to ear emergency. The locus showed no pleiotropic effects on grain pasting properties and agronomic traits except for spike length and number of spikelets per spike, and thus can be effectively used in breeding programs. The array of early heading dates caused by interactions of Eam5 gene with other maturity genes provides an opportunity to better fine tune heading dates with production environments, which can be critical factor in barley breeding.

Short Communication: The effect of seed hardness and malting characteristics on in situ dry matter digestibility of barley grain in beef heifers

Ding, S., Oba, M., Swift, M. L., Edney, M., O'Donovan, J. T., McAllister, T. A. and Yang, W. Z. 2015. Short Communication: The effect of seed hardness and malting characteristics on in situ dry matter digestibility of barley grain in beef heifers. Can. J. Anim. Sci. 95: 299–303. An in situ study was conducted to evaluate the relationship between ruminal dry matter digestibility (DMD) and seed hardness or malting characteristics of barley grain. Samples were selected for low and high values of seed hardness index (53 vs. 65; N = 18), beta-glucan content in wort (122 vs. 316 ppm; N = 18), diastatic power (146 vs. 203°L; N = 18), and friability (46 vs. 81%; N = 18) in malt, and incubated in the rumen of three beef heifers for 4, 12 and 48 h. In situ DMD did not vary with beta-glucan concentration or friability. However, barley grain with low seed hardness had lower (P = 0.02) in situ DMD than those with high seed hardness after 4 h of incubation. The barley samples with low diastatic power also had (P = 0.02) higher DMD than with high diastatic power after 4 h, a trend (P = 0.07) that continued after 12 h of incubation. Seed hardness and malting characteristics may have the potential to predict DMD of barley grain in the rumen. However, observed differences in in situ DMD were relatively minor, and we did not detect a relationship between malting characteristics and in situ DMD at longer incubation times. This suggests that the identified grain physical and malt parameters may impact the rate, but not the extent of barley grain digestion in the rumen.

Milling, water uptake, and modification properties of different barley (Hordeum vulgare L.) lots in relation to grain composition and structure

Milling properties, water uptake, and modification in malting were studied in 14 barley (Hordeum vulgare L.) lots from two consecutive crop years. In all barley lots studied, grains with lower β-glucan and protein content and higher starch content produced finer flours upon milling. Grains with lower β-glucan content also hydrated more rapidly during steeping. A detailed study of two cultivars from two crop years indicated that similar environmental conditions could induce a higher β-glucan content and concentration of aggregated B hordein in the peripheral endosperm and a lower proportion of C hordein entrapped among aggregated hordeins deeper within the endosperm. These characteristics were associated with production of coarser flours during milling as well as with slower water uptake and lower modification. However, the data do not distinguish between the effect of β-glucan content and that of hordein localization. Distribution of β-glucan or total protein within the kernel was not linked to hydration or modification.