Marker‐assisted breeding provides an opportunity for wheat breeders to introgress/pyramid genes of interest into breeding lines and to identify genes and/or quantitative trait loci in germplasm to be used as parents. Molecular markers were deployed to assist selection for disease resistance, agronomic and quality traits in several wheat cultivars released for commercial cultivation in Canada. Marker‐assisted breeding is routinely used in most wheat breeding programmes for rust resistance (leaf, stem and stripe rust), orange wheat blossom midge resistance, high grain protein concentration, Fusarium head blight and common bunt resistance. Markers are being used selectively within breeding programmes to target traits that relate to market class or regional adaptation. For example, marker‐assisted breeding for low lipoxygenase activity and low grain cadmium is being performed in durum breeding programmes and for enhancing stem solidness in programmes targeting resistance to the wheat stem sawfly. Markers are also being utilized for ergot resistance in durum wheat. Increased gluten strength is being selected with a marker for the overexpression of the Bx7 high‐molecular‐weight glutenin subunit. Marker‐assisted breeding is also being used to pyramid resistance genes against a group of stem rust races related to TTKS (Ug99), a disease that poses a serious threat to global wheat production. Development of tightly linked diagnostic markers and high‐throughput genotyping with SNP markers will result in more effective molecular wheat breeding in the near future and will open the door to genomic selection.

The inclusion of winter cereals in spring-annual rotations in the northern Great Plains may reduce weed populations and herbicide requirements. A broad range of spring and winter cereals were compared for ability to suppress weeds and maximize grain yield at Lacombe (2002 to 2005) and Lethbridge (2003 to 2005), Alberta, Canada. High seeding rates (≥ 400 seeds/m²) were used in all years to maximize crop competitive ability. Spring cereals achieved high crop-plant densities (> 250 plants/m²) at most sites, but winter cereals had lower plant densities due to winterkill, particularly at Lethbridge in 2004. All winter cereals and spring barley were highly effective at reducing weed biomass at Lacombe for the first 3 yr of the study. Weed suppression was less consistently affected by winter cereals in the last year at Lacombe and at Lethbridge, primarily due to poor winter survival. Grain yields were highest for spring triticale and least for spring wheat at Lacombe, with winter cereals intermediate. At Lethbridge, winter cereals had higher grain yields in 2003 whereas spring cereals had higher yields in 2004 and 2005. Winter cereals were generally more effective at suppressing weed growth than spring cereals if a good crop stand was established, but overlap in weed-competitive ability among cultivars was considerable. This information will be used to enhance the sustainable production of winter and spring cereals in traditional and nontraditional agro-ecological zones.

Randhawa, H., Puchalski, B. J., Frick, M., Goyal, A., Despins, T., Graf, R. J., Laroche, A. and Gaudet, D. A. 2012. Stripe rust resistance among western Canadian spring wheat and triticale varieties. Can. J. Plant Sci. 92: 713–722. Stripe rust (Puccinia striiformis Westend.) is an important pathogen of wheat in western Canada and worldwide. One hundred and four spring wheat and triticale varieties and cultivars were evaluated for resistance to stripe rust in nurseries at Lethbridge and Creston, BC, during 2009 and 2010. In the Canada Prairie Spring Red (CPSR) wheat class, newer varieties were more resistant compared with many of the older varieties. Among the white Canada Prairie Spring White (CPSW) wheats, Vista was moderately resistant, whereas Snowhite475 and Snowhite476 were susceptible. Little useful resistance was observed within the Canada Western Hard White Spring (CWHWS) class. Sixty percent of the Canada Western Red Spring (CWRS) wheats, including the currently popular varieties Lillian, Harvest and Kane, were resistant. Susceptible CWRS varieties that are extensively seeded in western Canada include AC Barrie, Superb and McKenzie, but also include the recently registered CDC Kernen and Vesper. The varieties were tested for the presence of the stripe rust genes Yr10, Yr17, Yr18 and Yr36 using molecular markers. Much of the stripe rust resistance, particularly in the CWRS, Canada Western Extra Strong (CWES), and CPSR wheat classes was attributed to the presence of adult plant resistance gene Yr18. Yr17 and Yr36 were also detected among CWRS and CWES varieties. However, the absence of markers for known genes in several resistant varieties indicated that uncharacterized genes for stripe rust occur among hexaploid wheats. Durum wheat and triticale varieties were universally resistant with the absence of tested markers. Therefore, there appear to be numerous sources of stripe rust resistance, both characterized and uncharacterized, among western Canadian spring wheat and triticale varieties.