| Wheat grain protein content (GPC) is an important quality factor in end-use functionality of spring wheat. The use of marker-assisted selection (MAS) may assist plant breeders to develop high GPC wheat. Two experiments were conducted using two populations developed by crossing low GPC cultivars 'Ember' and 'McVey' with 'Glupro', which contains a high GPC QTL from T. dicoccoides (DIC). In Experiment 1, three methods were used to select 30 high GPC genotypes from each population method combination of 250 plants: MAS using co-dominant microsatellite markers that flank the high GPC DIC QTL, phenotypic selection (PS) using near infra-red analysis, and random selection from a control population (CTL). The selected genotypes were grown in replicated field trials at three North Dakota environments in 2004 and 2005. In Experiment 2, each initial cross was backcrossed twice to its respective low GPC recurrent parent and then selfed to the BC2F2 generation. Microsatellite markers were used to screen 100 BC2F2 plants from each population. In each population, twelve plants from each DIC allele marker class were selected. The BC2F2 plants were selfed to BC2F4 generation and grown in replicated field trials at Prosper, ND, and Sabin, MN, in 2005. In Experiment 1, a contrast analysis among selection methods showed that mean GPC was greatest among lines using PS at two environments in 2004. There was no significant difference between MAS and PS in the remaining environments. The CTL population GPC means were significantly less at all environments. In Experiment 2, lines homozygous for DIC alleles had significantly higher GPC than their respective low GPC parents. The percentage of variation explained by the markers (r 2) was 30% and 15% at Prosper, ND, and Sabin, MN, respectively. In this study the use of PS was just as effective as MAS in selecting for high GPC genotypes and more effective in some environments. This likely is due to PS resulting in selection of both the major QTL and additional genes contributing to GPC. The use of molecular markers may be more effective in introgressing the desired high GPC DIC QTL in a backcrossing program. |
