|Campbell, Benjamin - Todd|
Submitted to: Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/8/2010
Publication Date: 3/1/2011
Citation: Ali, M.L., Baenziger, P.S., Ajlouni, Z.A., Campbell, B.T., Gill, K.S., Eskridge, K.M., Mujeeb-Kazi, A., Dweikat, I. 2011. Mapping QTL for agronomic traits on wheat chromosome 3A and a comparison of recombinant inbred chromosome line populations. Crop Science. 51:553-566. Interpretive Summary: In wheat and many other crops, complicated traits, such as grain yield, are quantitatively inherited and controlled by many genes. Bi-parental matings between parents differing for agronomic traits are typically used to develop segregating populations that are subsequently used to map the putative genes or quantitative trait loci associated with agronomic trait variation. Previously, a chromosome 3A recombinant inbred chromosome line population was developed between ‘Cheyenne’ and a chromosome substitution line Cheyenne (‘Wichita’ 3A) and used to map quantitative trait loci associated with agronomic trait variation on chromosome 3A. In the present study, a larger population of chromosome 3A recombinant inbred chromosome lines (223), which consisted of two subsets developed using recombinant monosomic (95) and double haploid methods (128), was used to more precisely map the quantitative trait loci. Overall, the 223 Cheyenne (Wichita 3A) recombinant inbred chromosome line population revealed greater power in the detection of quantitative trait loci than the two smaller subsets. Two previously identified grain yield quantitative trait loci were detected in the larger population and localized to smaller regions of chromosome 3A. A comparison of the genetic structure of the population subsets (128 and 95) revealed that, although their genetic maps differed in size, both population types performed similarly for their ability to detect quantitative trait loci.
Technical Abstract: Variation for wheat (Triticum aestivum L.) grain yield and its component traits was documented in a ‘Cheyenne’ x Cheyenne (‘Wichita’ 3A) recombinant inbred chromosome line population. In the present study, a population of 223 Cheyenne (Wichita 3A) recombinant inbred chromosome lines was used to map quantitative trait loci for grain yield and other related agronomic traits. A chromosome 3A linkage map spanning 106 centimorgans was constructed using 32 microsatellite markers. The population was evaluated in 6 environments in Nebraska during 2005-2007. Composite interval mapping detected a total of 19 quantitative trait loci for 7 agronomic traits that individually accounted for 4.6 to 16.8% of the phenotypic variation. Three small genomic segments, spanning 3.4, 5.3 and 5.3 centimorgan length, contained most of the quantitative trait loci. Two grain yield quantitative trait loci were detected in two environments as well as in analysis with data pooled over environments. For grain volume weight, a quantitative trait locus was detected in 5 out of the 6 environments while a plant height quantitative trait locus was detected in all environments. Wichita alleles contributed to the increased trait values for grain yield, spikes per square meter and grain volume weight while Cheyenne contributed alleles to the increased 1000-kernel weight, plant height and anthesis date. Both Cheyenne and Wichita contained alleles for increased number of kernels per spike. Over all, the 223 Cheyenne (Wichita 3A) recombinant inbred chromosome lines set revealed greater power in the detection of quantitative trait loci than the two smaller subsets – 128 Cheyenne (Wichita 3A) recombinant inbred chromosome lines developed using doubled haploids and 95 Cheyenne (Wichita 3A) recombinant inbred chromosome lines developed using recombinant monosomic lines. Neither of the subsets performed consistently better than the other in detecting quantitative trait loci. Thus, to develop recombinant inbred chromosome lines in the future, doubled haploids should be preferred as their development is simpler than the development of recombinant monosomic lines.