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15 Pags.- 5 Figs.- 3 TAbls.- Supp. Mat. Copyright Owner, the Authors. Under LicenceCC BY 4.0., One option to achieving greater resiliency for barley production in the face of climate change is to explore the potential of winter and facultative growth habits: for both types, low temperature tolerance (LTT) and vernalization sensitivity are key traits. Sensitivity to short-day photoperiod is a desirable attribute for facultative types. In order to broaden our understanding of the genetics of these phenotypes, we mapped quantitative trait loci (QTLs) and identified candidate genes using a genome-wide association studies (GWAS) panel composed of 882 barley accessions that was genotyped with the Illumina 9K single-nucleotide polymorphism (SNP) chip. Fifteen loci including 5 known and 10 novel QTL/genes were identified for LTT—assessed as winter survival in 10 field tests and mapped using a GWAS meta-analysis. FR-H1, FR-H2, and FR-H3 were major drivers of LTT, and candidate genes were identified for FR-H3. The principal determinants of vernalization sensitivity were VRN-H1, VRN-H2, and PPD-H1. VRN-H2 deletions conferred insensitive or intermediate sensitivity to vernalization. A subset of accessions with maximum LTT were identified as a resource for allele mining and further characterization. Facultative types comprised a small portion of the GWAS panel but may be useful for developing germplasm with this growth habit., Support was provided by the USDA-NIFA TCAP Project no. 2011-68002-30029.

Barley (Hordeum vulgare L.) is a cereal grown for animal feed, human consumption, and malting. Nutrient concentrations are important as they provide information regarding the dietary values of barley consumed by animals or human beings. In addition, grain nutrient removal may be useful for refining fertilizer recommendations. A study was conducted in 2015 and 2016 investigating the cultivar effects on grain yield, quality, and grain nutrient concentrations and removal under irrigated conditions for two-row barley cultivars. Adjunct and feed cultivars produced the highest yields compared with the all-malt and food cultivars. Specific quality and nutrient values were greater than or equal to in the food cultivar compared to the malt or feed cultivars. Variations in nutrient concentrations were measured among the adjunct and all-malt cultivars, which could potentially affect the malting and brewing qualities. Grain yield, quality, nutrient concentrations and nutrient removal varied among cultivars gr...

Arabinoxylans are an important quality component for which a simple and rapid analysis method useful for plant breeding needs to be developed. Bial’s orcinol–ferric chloride colorimetric method was modified to allow simultaneous analysis of at least 24 samples in a single run and in small volumes to measure water-extractable arabinoxylan (WEAX) in wheat meal. The modified parameters were reduction to 6N HCl, increased concentrations of orcinol and 10% ferric chloride, and a total volume of 500 µL. The sample turbidity was reduced by rapid cooling in an ice water bath followed by addition of 500 µL of 95% ethanol postincubation. The WEAX results from this protocol were compared with GC/MS values. The wheat varieties of Alta Blanca, Eltan, and Hatton were overestimated by 4.3, 1.5, and 0.9%, respectively, whereas the varieties of Eden, Darwin, Finley, and Boundary were underestimated by 14.4, 8.9, 11.3, and 3.6%, respectively. The modified procedure is useful to determine a range of WEAX concentrations in w...

Arabinoxylan is an important hemicellulose potentially affecting wheat baking qualities, barley malt quality, and may impart prebiotic benefits. Water-extractable (WEAX) and total arabinoxylan (TOAX) were characterized in 204 wheat and barley accessions, respectively, using an orcinol-ferric chloride assay. WEAX measurement accuracy was optimum when glucose concentration was greater than 12–13 times pentose concentration. The modified method removed enough excess glucose spectral absorbance to make the corrected and uncorrected lines different, but still significantly correlated (p = 0.009, R = 0.94). Mean WEAX (expressed as percentage WEAX of TOAX) for the wheat accessions was 15.90%, ranging from 8.82% to 24.87%, and for barley accessions WEAX the mean was 7.10%, and ranged from 2.98% to 13.86%. Conclusions are 1) the assay is useful for a breeding program because of its semi-high throughput design for the simultaneous analysis of 16 (WEAX) to 40 (TOAX) barley lines or 24 (WEAX) to 40 (TOAX) wheat lines, 2) the trichromatic measurement reduces the impact of glucose, and 3) the broad range of WEAX measured showed that barley and wheat accessions vary in their extractable and unextractable components.

Bioethanol is an important liquid fuel complement. Barley is a potential alternative raw material for ethanol production because its by-product is a nutritious feed. The barley m351mutant, which has a mutation for low beta-glucan content, was tested for its ethanol production efficiency and feed fraction quality in a pilot fermentation experiment. Grain samples of m351 and the corresponding wild type of Harrington were either treated or untreated with beta-glucanase during the ethanol production process. Compared to the corresponding wild-type line, m351 produced the same amount of ethanol. More importantly, the feed fraction derived from the fermentation process showed 5 % more protein and 7 % less beta-glucan than that from the wild type, indicating that the feed fraction from m351 was more valuable. The experiments provided evidence that m351 is a useful genetic resource for developing barley cultivars for use in bioethanol production.

Barley m38 mutant was selected for its high level of mixed-linkage (1,3),(1,4)-β-d-glucan (MLG) in the grain. This elevated level of MLG was found to be associated with decreased amylose accumulation as well as other chemical composition alterations. Molecular characterization results revealed m38 as a new allele of the Waxy gene, encoding an endosperm-specific granule-bound starch synthase I (GBSSI). Additional mapping data from amylose phenotype and GBSSI gene specific markers supported the conclusion of the GBSSI mutation in m38. The m38 locus contains a nucleotide alteration that would result in the substitution of glycine at position 263 with serine in the putative adenosine-5′-diphosphate-glucose binding domain. This amino acid substitution alters loop structures on the exterior surface of the folded protein and may affect its enzyme activity. Characterizations of m38 in this report provide for a new allele of the Waxy gene and additional evidence of pleiotropic effects on other chemical co...

The chemical induced barley mutant m351 was first selected for its low level of mixed-linkage (1–3,1–4) beta-D-glucan (MLG) in an experimental effort to search for barley lines with varied grain MLG contents. The MLG decrease in m351 was associated with increased levels of fructans and crude fiber, but maintained the same plant characteristics under field conditions. The mutation was mapped to a genetic locus flanked by two SSR markers, Bmag369 and Bmag564, on chromosome 7H. Molecular cloning of the CslF6 gene from the m351 line revealed the presence of a point mutation, causing a substitution of an alanine for threonine at position 849 in the amino acid sequence of the corresponding protein. The resultant protein retains some functionality and affects other components in the m351 grain. Those metabolic changes associated with MLG reduction in m351 is the first case reported of a partially functional CslF6 gene in cereal grains. The results contribute to better understanding of the functional effects of the CslF6 gene and the mutant has potential implications in grain end-use quality improvement.

Six hundred thirty five oat ( L.) lines and 4561 single-nucleotide polymorphism (SNP) loci were used to evaluate population structure, linkage disequilibrium (LD), and genotype–phenotype association with heading date. The first five principal components (PCs) accounted for 25.3% of genetic variation. Neither the eigenvalues of the first 25 PCs nor the cross-validation errors from = 1 to 20 model-based analyses suggested a structured population. However, the PC and = 2 model-based analyses supported clustering of lines on spring oat vs. southern United States origin, accounting for 16% of genetic variation ( < 0.0001). Single-locus -statistic () in the highest 1% of the distribution suggested linkage groups that may be differentiated between the two population subgroups. Population structure and kinship-corrected LD of = 0.10 was observed at an average pairwise distance of 0.44 cM (0.71 and 2.64 cM within spring and southern oat, respectively). On most linkage groups LD decay was slower within southern lines than within the spring lines. A notable exception was found on linkage group Mrg28, where LD decay was substantially slower in the spring subpopulation. It is speculated that this may be caused by a heterogeneous translocation event on this chromosome. Association with heading date was most consistent across location-years on linkage groups Mrg02, Mrg12, Mrg13, and Mrg24.

High beta-glucan (BG) barleys (Hordeum vulgare L.) have major potential as food ingredients due to their well-known health benefits. Quantitative trait loci (QTL) associated with BG have been reported in traditional barley varieties with intermediate levels of BG, but no QTL studies have been reported in hull-less barley varieties with high BG levels. In this study, QTL analysis was performed to identify markers linked to high BG and amylose in the hull-less barley varieties Falcon (4–5 % BG) and Azhul (8–9 % BG) using a newly developed recombinant inbred line (RIL) mapping population. The population was grown over 3 years (2007–2009) at sites in Yuma, AZ, USA; Leeston, New Zealand; Aberdeen, ID, USA; and Tetonia, ID, USA. We identified 17 QTL associated with either BG or amylose content. QTL contributing to high BG were located on chromosomes 3H, 4H, 5H, 6H and 7H, while QTL contributing to amylose were located on chromosomes 1H, 5H and 7H. Additionally, we identified QTL affecting both BG and amylose content located on chromosomes 1H and 7H. Transgressive segregation was observed in some of the RILs and exceptions were discovered contradicting an inverse relationship between BG and amylose. This work will provide the basis for gene cloning and marker-assisted selection in combination with traditional field selection to improve barley breeding for high BG content.

Rapid and economical measurement of amylose content in barley is important for genetic study and breeding improvement of this trait. Seventeen genotypes with a wide range of amylose contents were used to compare the amylose measurement accuracy of the cost-effective iodine–potassium iodide (I:KI) method to the commercially available enzyme-based Megazyme protocol. Comparable accuracy from I:KI was demonstrated in low amylose samples (below 10% dried base), as were limitations in regular or high amylose samples. To address the major cost of sample preparation in nutritional trait analysis, the I:KI method was also employed for amylose detection from β-glucan and free phosphate assay samples. Results indicated that samples used in β-glucan and phosphate assays could be further utilized for amylose measurement. Amylose detection accuracy using I:KI method from those assayed samples is comparable to that using the Megazyme method in low and regular amylose samples. Development of protocols for the double assays from one grain sample will significantly reduce the labor cost associated with sample preparation and will streamline the screening of early generation barley populations, where seed sample amounts are limited.

Consumption of oat (Avena sativa L.) products has been credited with reducing the risk of various diseases. This may be due in part to tocopherol content. Studies have shown variation in α-tocotrienol, α-tocopherol, and total tocopherol levels among oat cultivars, however, the genetic basis of these traits is unknown. The objectives of this study were to examine the genetic mechanisms affecting tocopherol levels in the Ogle1040/TAM O-301 population and to identify quantitative trait loci (QTLs) useful for improving tocopherol levels in oat. The population was grown in Aberdeen and Tetonia, ID, over 4 yr. Alpha-tocotrienol, α-tocopherol, and total tocopherol contents were measured in harvested seed. Mean levels of all three tocopherol measurements were higher from the irrigated Aberdeen location than from the nonirrigated Tetonia location. One major and four minor QTLs were detected, which accounted for a majority of the α-tocotrienol variation across all locations, while six minor QTLs accounted for a majority of the α-tocopherol variation. Only one QTL affecting total tocopherol was detected apart from QTLs affecting α-tocotrienol and α-tocopherol. Overall, we have identifi ed markers linked to QTLs affecting α-tocotrienol and α-tocopherol. Since the highest level of both tocopherols in lines of the population were higher than from previously tested cultivars, these QTLs should be useful to increase specifi c tocopherol levels.

The current enzymatic assay approach (AACC International Approved Method 32-23) for the measurement of mixed-linkage β-glucan in small grains was modified to a cost-efficient and high-throughput format without compromising the accuracy of the results. Ten barley (Hordeum vulgare L.) genotypes used in the study represented a wide range of β-glucan content levels. A reduced reaction volume is used in the new protocol to adapt to a 96-well plate format. The volume of key components lichenase and β-glucosidase were reduced to 25% of the volume required in the original protocol and the cost per sample was reduced to 22% of that in the original protocol. Labor cost was also decreased to 25% of the original protocol as a result of format changes. The accuracy of the measurement from the modified protocol was comparable to the current standard enzymatic procedure. β-Glucan measurement accuracy of the modified and original protocols were also compared using 21 oat (Avena sativa L.) samples. The results in...

Identifying polymerase chain reaction (PCR)-based markers in crop genomes and amplifying them with specific primer pairs has provided convenient molecular markers for mapping projects. Oat (Avena sativa L.) lags behind other crops in the utilization of PCR-based markers due to limited development of genomic and genetic resources in Avena species. We surveyed 356 genome-derived simple sequence repeat (SSR) markers from wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.), chosen on the basis of even dispersal across different chromosomes, to search for an alternate method of expanding the PCR-based marker pool in oat. Primer pairs for these SSR markers were tested for amplification and polymorphism between parental lines from Ogle1040/TAM-0-301 (OT) and Kanota/Oglel157 (KO) mapping populations. Eighty-nine of 210 wheat primer pairs (42%) and 56 of 146 barley primer pairs (38%) successfully amplified sequences In oat. Forty-five percent of the amplified markers, representing 19% of the total markers, showed polymorphism between parental lines of at least one mapping population. The polymorphism was primarily the presence or absence of a product band. Fifteen PCR products from 10 primer pairs were tested for reproducibility by amplifying each marker in the OT population. When assayed with the same PCB conditions used in the survey, the segregation ratio of 14 markers did not differ from the 1:1 ratio expected for a single locus. This study indicates that genomic SSR primer pairs from wheat and barley may be a good way to efficiently generate PCR-based DNA markers for oat genetics research.

Continued growth and intensi¢cation of aquaculture production depends upon the development of sustainable protein sources to replace ¢sh meal in aquafeeds. This document reviews various plant feedstuis, which currently are or potentially may be incorporated into aquafeeds to support the sustainable production of various ¢sh species in aquaculture. The plant feedstuis considered include oilseeds, legumes and cereal grains, which traditionally have been used as protein or energy concentrates as well as novel products developed through various processing technologies. The nutritional composition of these various feedstuis are considered along with the presence of any bioactive compounds that may positively or negatively aiect the target organism. Lipid composition of these feedstuis is not speci¢cally considered although it is recognized that incorporating lipid supplements in aquafeeds to achieve proper fatty acid pro¢les to meet the metabolic requirements of ¢sh and maximize human health bene¢ts are important aspects. Speci¢c strategies and techniques to optimize the nutritional composition of plant feedstuis and limit potentially adverse eiects of bioactive compounds are also described. Such information will provide a foundation for developing strategic research plans for increasing the use of plant feedstuis in aquaculture to reduce dependence of animal feedstuis and thereby enhance the sustainability of aquaculture.

*† These two authors contributed equally to this work. Summary In tobacco and other Solanaceae species, the tobacco N gene confers resistance to tobacco mosaic virus (TMV), and leads to induction of standard defense and resistance responses. Here, we report the use of Ntransgenic tomato to identify a fast-neutron mutant, sun1-1 (suppressor of N), that is defective in N-mediated resistance. Induction of salicylic acid (SA) and expression of pathogenesis-related (PR) genes, each signatures of systemic acquired resistance, are both dramatically suppressed in sun1-1 plants after TMV treatment compared to wild-type plants. Application of exogenous SA restores PR gene expression, indicating that SUN1 acts upstream of SA. Upon challenge with additional pathogens, we found that the sun1-1 mutation impairs resistance mediated by certain resistance (R) genes, (Bs4, I, and Ve), but not others (Mi-1). In addition, sun1-1 plants exhibit enhanced susceptibility to TMV, as well as to virulent pathogens. sun1-1 has been identified as an EDS1 homolog present on chromosome 6 of tomato. The discovery of enhanced susceptibility in the sun1-1 (Le_eds1-1) mutant plant, which contrasts to reports in Nicotiana benthamiana using virus-induced gene silencing, provides evidence that the intersection of R gene-mediated pathways with general resistance pathways is conserved in a Solanaceous species. In tomato, EDS1 is important for mediating resistance to a broad range of pathogens (viral, bacterial, and fungal pathogens), yet shows specificity in the class of R genes that it affects (TIR-NBS-LRR as opposed to CC-NBS-LRR). In addition, a requirement for EDS1 for Ve-mediated resistance in tomato exposes that the receptor-like R gene class may also require EDS1.

Tocochromanols are recognized for nutritional content, plant stress response, and seed longevity. Here we present a systems biological approach to characterize and develop predictive assays for genes affecting tocochromanol variation in barley. Major QTL, detected in three regions of a SNP linkage map, affected multiple tocochromanol forms. Candidate genes were identified through barley/rice orthology and sequenced in genotypes with disparate tocochromanol profiles. Gene-specific markers, designed based on observed polymorphism, mapped to the originating QTL, increasing R2 values at the respective loci. Polymorphism within promoter regions corresponded to motifs known to influence gene expression. Quantitative PCR analysis revealed a trend of increased expression in tissues grown at cold temperatures. These results demonstrate utility of a novel method for rapid gene identification and characterization, and provide a resource for efficient development of barley lines with improved tocochromanol profiles.

The rp1 locus of maize controls race-specific resistance to the common rust fungus Puccinia sorghi. Four mutant or recombinant Rp1 alleles (rp1-NC3, Rp1-D21, Rp1-MD19, and Rp1-Kr1N) were identified. They condition necrotic phenotypes in the absence of the rust pathogen. These Rp1 lesion mimics fall into three different phenotypic classes: (1) The rp1-NC3 and Rp1-D21 alleles require rust infection or other biotic stimulus to initiate necrotic lesions. These alleles react strongly to all maize rust biotypes tested and also to nonhost rusts. (2) The Rp1-MD19 allele, which has a similar phenotype, also requires a biotic stimulus to initiate lesions. However, Rp1-MD19 shows the race specificity of the Rp1-D gene. (3) The Rp1-Kr1N allele specifies a diffuse necrotic phenotype in the absence of any biotic stimulus and a race-specific reaction when inoculated with maize rust.

The Rp1 locus of maize is a complex rust resistance locus where multiple resistance genes are clustered. Rare recombination events between Rp1 genes or alleles can produce two or more detectable genes linked in coupling phase. Such ‘compound’ genes can then be manipulated as a single gene in breeding programs. Several compound Rp1 genes, each carrying two or three tightly linked resistance genes, were constructed to test their utility in controlling common rust. While none of the lines carrying single Rp1 genes were resistant to all of the characterized North American P. sorghi biotypes, most of the two component and all of the three component Rp1 complexes were resistant. The potential for utilization of compound resistance genes in other crop species is discussed.

Silks of 18 maize (Zea may L.) F1 hybrids were treated with different combinations of 9 growth regulators, colchicine, and dimethyl sulfoxide (DMSO) for the purpose to induce apomixis (agamospermy) in 1988 and 1989. Hybrid K301 × K303 gave the highest (0.36%) average frequency of seed induction among the hybrids. The most effective treatments were DMSO, gibberellic acid plus 6-benzyl aminopurine (6-BA), and DMSO plus methanesulfonic acid. Individually, the highest frequency of seed induction was 1.4% for hybrid K731×K306 when treated with α-naphthalene acetic acid (NAA)-zeatin mixture. The frequency of seed induction seemed to depend partially on the interaction between chemicals and hybrids. Cytological observation of root-tip cells indicated that the majority of the seeds obtained were diploid, some were mixoploid, and a few were haploid. Diploid plants from induced seeds from the same parent were morphologically uniform and resembled the parent. Variations in plant and ear heights were comparable to those of the hybrid parent. Cytological and morphological investigations suggested that the chemically induced seeds originated mainly from somatic tissue but occasionally came from reduced cells in the embryo sac, leading to haploids. The results showed that chemical induction of adventitious embryony in maize hybrids is possible, but the more effective chemicals, their concentrations, and ways of application for increasing the frequency of seed induction need to be explored for practical use.

Rp1 is a complex rust resistance locus of maize. Susceptible recombinants can be observed at variable frequencies from different Rp1 heterozygotes and homozygotes by crossing-over and unequal crossing-over. In addition, susceptible progeny have been observed from one heterozygote that were not associated with crossing-over, as indicated by flanking marker analysis. We analyzed testcross progeny from this cross (Rp1-C/Rp1-J) and a related cross (Rp1-F/Rp1-J) to identify noncrossover type derivatives, to estimate their frequency, and to determine the mechanism by which they arise. Testcross progeny were screened sequentially with two different rust isolates to assay each gene individually. Both susceptible noncrossover types and those with the combined resistance of each parent were identified in approximately equal frequencies. Patterns of recombination indicated that the noncrossover type derivatives arose by gene conversion as opposed to mutation or intrachromosomal crossing-over. While gene conversion events were observed frequently in both crosses (approx. 7 × 10−4), they were less frequent than crossover derivatives. Key words: Puccinia, disease resistance, recombination, gene family, restriction fragment length polymorphism.

The genetics of the “gene-for-gene” interaction between disease resistance loci of plants and avirulence genes of pathogens was first characterized in detail by Flor [1, 2]. These studies suggested that the role of this abundant class of resistance (R) genes is in the recognition of the presence of the pathogen, leading to activation of biochemical defense activities. Providing support for this recognition/signaling role, the first “gene-for-gene” R locus to be molecularly cloned, Pto of tomato [3], has been found to encode a serine/threonine kinase like those known to be involved in other signal transduction processes.