Mapping of the oat crown rust resistance gene Pc91.

Crown rust is an important disease of oat caused by Puccinia coronata Corda f. sp. avenae Eriks. Crown rust is efficiently and effectively managed through the development of resistant oat varieties. Pc91 is a seedling crown rust resistance gene that is highly effective against the current P. coronata population in North America. The primary objective of this study was to develop DNA markers linked to Pc91 for purposes of marker-assisted selection in oat breeding programs. The Pc91 locus was mapped using a population of F7-derived recombinant inbred lines developed from the cross 'CDC Sol-Fi'/'HiFi' made at the Crop Development Centre, University of Saskatchewan. The population was evaluated for reaction to P. coronata in field nurseries in 2008 and 2009. Pc91 mapped to a linkage group consisting of 44 Diversity Array Technology (DArT) markers. DArTs were successfully converted to sequence characterized amplified region (SCAR) markers. Five robust SCARs were developed from three non-redundant DArTs that co-segregated with Pc91. SCAR markers were developed for different assay systems, such that SCARs are available for agarose gel electrophoresis, capillary electrophoresis, and Taqman single nucleotide polymorphism detection. The SCAR markers accurately postulated the Pc91 status of 23 North American oat breeding lines.

Nutrient retention and growth performance of chicks given low-phytate conventional or hull-less barleys.

1. The experimental barley samples included 4 hulled and one hull-less low-phytate barley cultivars and two commercial barley varieties as controls. 2. The diets were provided in meal form, with the experimental barley samples constituting the cereal source. Two additional treatments were added for each of the control varieties in which intermediate and recommended levels of phosphorus were provided. 3. A completely randomised design was used with 5 replicates of 5 chicks per treatment. The chicks were grown from 2 to 14 d of age with excreta collected over the subsequent 3 d. 4. Although total phosphorus levels were similar for all barley samples, there were large differences in their phytate content, which ranged from less than 0.5 to 13.8 g/kg. M2 955 hulled barley exhibited the lowest phytate and the highest phosphorus solubility. 5. There was a negative linear relationship between grain phytate and weight gain and with bone ash. The low-phytate hulled barleys M2 955 and the low-phytate hull-less barley (lpa1-1H) gave better feed conversion (8%) than controls. The hull-less low-phytate barley gave significantly higher total phosphorus (18%) and soluble phosphorus retention (23%) than the hull-less control. The low-phytate samples tended to give lower excreta phosphorus levels (total and soluble), but the effect was significant only for the hull-less samples. Amino acid retention was significantly higher for the low-phytate hull-less barley than the control (4%). 6. Overall, the results suggest that using low-phytate barley can result in similar growth while using less supplemental phosphorus, reducing waste phosphorus by more than 50%.

Mapping quantitative trait loci associated with barley net blotch resistance.

Net blotch of barley, caused by Pyrenophora teres Drechs., is an important foliar disease worldwide. Deployment of resistant cultivars is the most economic and eco-friendly control method. This report describes mapping of quantitative trait loci (QTL) associated with net blotch resistance in a doubled-haploid (DH) barley population using diversity arrays technology (DArT) markers. One hundred and fifty DH lines from the cross CDC Dolly (susceptible)/TR251 (resistant) were screened as seedlings in controlled environments with net-form net blotch (NFNB) isolates WRS858 and WRS1607 and spot-form net blotch (SFNB) isolate WRS857. The population was also screened at the adult-plant stage for NFNB resistance in the field in 2005 and 2006. A high-density genetic linkage map of 90 DH lines was constructed using 457 DArT and 11 SSR markers. A major NFNB seedling resistance QTL, designated QRpt6, was mapped to chromosome 6H for isolates WRS858 and WRS1607. QRpt6 was associated with adult-plant resistance in the 2005 and 2006 field trials. Additional QTL for NFNB seedling resistance to the more virulent isolate WRS858 were identified on chromosomes 2H, 4H, and 5H. A seedling resistance QTL (QRpts4) for the SFNB isolate WRS857 was detected on chromosome 4H as was a significant QTL (QRpt7) on chromosome 7H. Three QTL (QRpt6, QRpts4, QRpt7) were associated with resistance to both net blotch forms and lines with one or more of these demonstrated improved resistance. Simple sequence repeat (SSR) markers tightly linked to QRpt6 and QRpts4 were identified and validated in an unrelated barley population. The major 6H QTL, QRpt6, may provide adequate NFNB field resistance in western Canada and could be routinely selected for using molecular markers in a practical breeding program.

Effect of phytase supplementation on phosphorus digestibility in low-phytate barley fed to finishing pigs.

Forty crossbred barrows (Camborough 15 Line female x Canabred sire) weighing an average of 79.6 +/- 8.0 kg were used in a factorial design experiment (5 barleys x 2 enzyme levels) conducted to determine the effects of phytase supplementation on nutrient digestibility in low-phytate barleys fed to finishing pigs. The pigs were assigned to one of 10 dietary treatments comprised of a normal 2-rowed, hulled variety of barley (CDC Fleet, 0.26% phytate) or 2 low-phytate hulled genotypes designated as LP422 (0.14% phytate) and LP635 (0.09% phytate). A normal, hulless barley (CDC Dawn, 0.26% phytate) and a hulless genotype designated as LP422H (0.14% phytate) were also included. All barleys were fed with and without phytase (Natuphos 5000 FTU/kg). The diets fed contained 98% barley, 0.5% vitamin premix, 0.5% trace mineral premix, 0.5% NaCl and 0.5% chromic oxide but no supplemental phosphorus. The marked feed was provided for a 7-day acclimatization period, followed by a 3-day faecal collection. In the absence of phytase, phosphorus digestibility increased substantially (P < 0.05) as the level of phytate in the barley declined. For the hulled varieties, phosphorus digestibility increased from 12.9% for the normal barley (0.26% phytate) to 35.3 and 39.8% for the two low-phytate genotypes (0.14 and 0.09% phytate respectively). For the hulless varieties, phosphorus digestibility increased from 9.2% for the normal barley (0.26% phytate) to 34.7% for the hulless variety with 54% of the normal level of phytate (0.14% phytate). In contrast, when phytase was added to the diet, there was little difference in phosphorus digestibility between pigs fed normal barley and those fed the low-phytate genotypes (significant barley x enzyme interaction, P = 0.01). For the hulled varieties, phosphorus digestibility was 50.1% for the barley with the normal level of phytate (0.26% phytate) compared with 51.1 and 52.4% for the varieties with 54 and 35% of the normal level of phytate (0.14 and 0.09% phytate respectively). For the hulless varieties, phosphorus digestibility increased from 47.1% for the normal barley (0.26% phytate) to 54.4% for the hulless variety with 54% of the normal level of phytate (0.14% phytate). In conclusion, both supplementation with phytase and selection for low-phytate genotypes of barley were successful in increasing the digestibility of phosphorus for pigs. Unfortunately, the effects did not appear to be additive. Whether or not swine producers will choose low-phytate barley or supplementation with phytase as a means to improve phosphorus utilization, will likely depend on the yield potential of low-phytate barley and the additional costs associated with supplementation with phytase.

A molecular linkage map with associated QTLs from a hulless x covered spring oat population.

In spring-type oat ( Avena sativa L.), quantitative trait loci (QTLs) detected in adapted populations may have the greatest potential for improving germplasm via marker-assisted selection. An F(6) recombinant inbred (RI) population was developed from a cross between two Canadian spring oat varieties: 'Terra', a hulless line, and 'Marion', an elite covered-seeded line. A molecular linkage map was generated using 430 AFLP, RFLP, RAPD, SCAR, and phenotypic markers scored on 101 RI lines. This map was refined by selecting a robust set of 124 framework markers that mapped to 35 linkage groups and contained 35 unlinked loci. One hundred one lines grown in up to 13 field environments in Canada and the United States between 1992 and 1997 were evaluated for 16 agronomic, kernel, and chemical composition traits. QTLs were localized using three detection methods with an experiment-wide error rate of approximately 0.05 for each trait. In total, 34 main-effect QTLs affecting the following traits were identified: heading date, plant height, lodging, visual score, grain yield, kernel weight, milling yield, test weight, thin and plump kernels, groat beta-glucan concentration, oil concentration, and protein. Several of these correspond to QTLs in homologous or homoeologous regions reported in other oat QTL studies. Twenty-four QTL-by-environment interactions and three epistatic interactions were also detected. The locus controlling the covered/hulless character ( N1) affected most of the traits measured in this study. Additive QTL models with N1 as a covariate were superior to models based on separate covered and hulless sub-populations. This approach is recommended for other populations segregating for major genes. Marker-trait associations identified in this study have considerable potential for use in marker-assisted selection strategies to improve traits within spring oat breeding programs.

Inheritance of resistance to covered smut in barley and development of a tightly linked SCAR marker.

Inheritance of resistance to covered smut in the barley line Q21861 was studied using a doubled-haploid population produced by crossing Q21861 with the line SM89010. Based on 3 years of screening in the field and two seasons in the greenhouse, segregation for resistance/susceptibility fits a one-gene ratio, indicating a single major gene for resistance in Q21861. Of 440 random 10-mer primers tested using bulked segregant analysis, one primer (OPJ10) resulted in a reproducible polymorphic band. RAPD marker OPJ10(450) co-segregated in repulsion with the covered smut resistance. This marker was converted to a sequence-characterized amplified region (SCAR) marker linked in coupling (5.5 cM) with the covered smut resistant gene in Q21861. The SCAR marker was amplified in the line TR640 which is also resistant to covered smut, but not in the other resistant lines. The SCAR marker will be useful for marker-assisted selection for covered smut in barley breeding programs.

Variation in total and soluble beta-glucan content in hulless barley: effects of thermal, physical, and enzymic treatments.

Total and soluble beta-glucan content and effects of various treatments of barley grain on extractability and molecular characteristics of soluble beta-glucan were studied. Four types of hulless barley (normal, high amylose, waxy, and zero amylose waxy) from 29 registered and experimental genotypes were analyzed. For each, moisture, protein, amylose, 100 kernel weight, starch, beta-glucan (total and soluble), beta-glucanase activity, and slurry viscosity were determined. Significant differences in total beta-glucan were observed among the groups, with average values of 7. 49%, 6.86%, 6.30%, and 4.38% for high amylose, waxy, zero amylose waxy, and normal barley, respectively. The extractability of beta-glucan in high amylose barley was relatively low (20.6-29.7%) compared to that in normal (29.8-44.3%), zero amylose waxy (34.0-52. 5%), and waxy (36.7-52.7%) barley genotypes. Viscosity of barley flour slurries was affected by the content of soluble beta-glucans, beta-glucanase activity, and molecular weight of beta-glucans. Hydrothermal treatments (autoclaving and steaming) of barley had no effect on extractability of beta-glucans, but prevented enzymic hydrolysis of beta-glucans, and thereby substantially improved their molecular weight. The addition of enzymes (protease and esterase) during extraction and/or physical treatments (sonication) increased extractability of beta-glucans from barley.

Identification of RAPD markers for common root rot and spot blotch (Cochliobolus sativus) resistance in barley.

The identification of RAPD markers associated with genes for resistance to Cochliobolus sativus in barley would increase the efficiency of gene manipulation by reducing the number of lines that must be evaluated from a resistant by susceptible cross and by allowing selection during the off season. Two barley crosses consisting of resistant and susceptible parent genotypes ('Virden' x 'Ellice' and Fr926-77 x 'Deuce', both 2 row x 6 row crosses) and more than 140 homozygous progeny lines were rated for their reactions in field nurseries to common root rot and in a controlled environment for spot blotch. Putative RAPD markers were identified using bulked segregant analysis followed by individual progeny line analyses. Polymorphisms associated with disease reaction were detected between bulked segregant samples as differences in the band intensity of DNA fragments. The bulked segregant samples were screened against 186 RAPD primers (decamers) using the polymerase chain reaction. For the cross Fr926-77 x 'Deuce', one RAPD marker was obtained that did not segregate as expected but was associated with both diseases. For the cross 'Virden' x 'Ellice', a single RAPD marker was obtained that did not have the expected segregation ratio but was associated with spot blotch reaction. One RAPD marker linked to 2-rowed and 6-rowed spike locus was obtained in each cross, and both the marker and row type were associated with common root rot and spot blotch reactions. For the cross 'Virden' x 'Ellice', a linkage group consisting of three RAPD markers was associated with common root rot and spot blotch reaction. The genes associated with these markers condition significant levels of resistance to C. sativus and may be used to increase the speed and precision of resistance gene manipulation in barley germplasm.

Screening salt-tolerant barley genotypes via F1 anther culture in salt stress media.

Anthers of two six-row barley cultivars Diamond (a germination salt sensitive cultivar) and Men Yuan Liang Lan (a germination salt tolerant cultivar), and their F1 reciprocal crosses were cultured in liquid media containing 0, 0.4, 0.6, and 0.8% Na2SO4. A total of 138 green pollen plants were obtained: 7 from Na2SO4 media, 128 from Na2SO4 free medium. Seeds of two successive generations of 61 pollen plants were germinated in a series of Na2SO4 solution (0 to 5.5%). It was found that among 37 progenies from F1 pollen in Na2SO4 free medium, 11 were as sensitive as "Diamond", 12 were intermediate to the two parents, 7 were equal to the salt tolerant parent and 7 were more tolerant to Na2SO4 than 'Men Yuan Liang Lan'. Whereas, no progeny from F1 pollen in high salt media was as susceptible as the susceptible parent; 2 were intermediate, 2 were equal to the salt tolerant parent and 2 were more tolerant than the salt tolerant parent. The results indicate that culturing anthers in Na2SO4 media effectively eliminated salt susceptible progenies. All 16 microspore-derived lines of Diamond were as susceptible as 'Diamond' to Na2SO4. The 5 lines from 'Men Yuan Liang Lan' microspores were as resistant to Na2SO4 as 'Men Yuan Liang Lan'. All of the lines breed-true. The results indicate that the lines exhibiting elevated levels of tolerance to salt probably resulted from recombination of genes rather than from spontaneous mutation.