Wheat breeding assisted by markers: CIMMYT’s experience

Abstract

Significant progress has been made in the characterization of loci controlling traits of importance using molecular markers. A number of markers are currently available in wheat for genes of interest to the breeders. Markers can be used to better characterize parental material, thereby improving the efficiency and effectiveness of parental selection for crossing and to track genes in segregating progenies through the selection process. Although a number of breeding programs are using molecular markers at modest levels, the costs associated with marker assisted selection (MAS) are frequently cited as the main constraint to their wide-spread use by plant breeders. However, this is likely to change when user-friendly, high-throughput, automated marker technologies based on single nucleotide polymorphisms become available. These evolving technologies will increase the number of available markers, and will improve the efficiency, throughput, and cost effectiveness of MAS, thereby making it more attractive and affordable to many breeding programs. This article examines the extent to which molecular markers have been used at the International Maize and Wheat Improvement Center (CIMMYT) in applied wheat breeding and reviews the limited publicly available information on MAS from other wheat breeding programs. As markers are currently available for relatively few traits, we believe that MAS must be integrated with ongoing conventional breeding to maximize its impact. When used in tandem with phenotypic selection, MAS will improve response to selection for certain traits, thereby increasing rates of genetic progress.

Genomic selection for durable stem rust resistance in wheat

“…Molecular markers have already become important for predicting breeding value and are especially important for combining R-genes in adapted germplasm (Singh et al 2006;William et al 2007). The use of MAS in plant breeding is now routine in commercial breeding programs to increase gains from selection per unit time (Eathington et al 2007).…”

“…To enhance durability, plant breeders can use marker-assisted selection (MAS) to more easily pyramid disease resistance genes (William et al 2007). Consequently, efforts aimed at quickly developing wheat varieties resistant to Ug99 (formally known as race TTKSK), a relatively new and highly virulent race of the stem rust pathogen (Puccinia graminis f. sp.…”

Identification of Sr genes in new common wheat sources of resistance to stem rust race Ug99 using molecular markers

“…В настоящее время эти маркеры широко используются для скрининга сортов в США и международном центре СИММИТ (William et al, 2007;Singh et al, 2008). Диа-гностические фрагменты размером 500 и 200 п. н. для Sr24#12 и Sr24#50 соответственно (Mago et al, 2005) были выявлены у положительного контроля (линии BTSR24AG) и у линии GT 96/90, что свидетельствует о наличии у нее данного гена.…”

Genetics Options for Improving the Productivity of Wheat in Water‐Limited and Temperature‐Stressed Environments

“…This ease of assessment and relative simplicity of inheritance has driven the development of molecular markers for disease resistance in wheat. Molecular markers have allowed the plant breeder to pyramid disease genes both in the presence and absence of the disease (William et al 2007). In contrast, the complexity of inheritance and response to environment has hampered attempts at establishing accurate phenotypes for the abiotic stresses.…”