In an elite cross of maize a major quantitative trait locus controls one-fourth of the genetic variation for grain yield
1995
Ajmone-Marsan, P. | Monfredini, G. | Ludwig, W.F. | Melchinger, A.E. | Franceschini, P. | Pagnotto, G. | Motto, M. (Istituto Sperimentale per la Cerealicoltura, Bergamo (Italy))
Quantitative trait loci (QTLs) for grain yield, dry matter content and test weight were identified in an F2 segregating population derived from a single cross between two elite maize lines (B73 and A7) and test crossed to two genetically divergent inbreds. Most of the QTLs inferred were consistent across locations, indicating that the expression of the genes influencing the traits under investigation was largely independent of the environment. By using two different tester lines it was found that QTLs exhibited by one tester may not necessarily be detected with the second one. Only loci with larger effects were consistent across testers, suggesting that interaction with tester alleles may contribute to the identification of QTLs in a specific fashion. Analysis across both testers revealed four significant QTLs for grain yield that explained more than 35% of the phenotypic variation and showed an overall phenotypic effect of more than 2t/ha. The major QTL for grain yield, located in the proximity of the Nucleolus Organiser Region, accounted for 24.5% of the phenotypic variation for grain yield and showed an average effect of allele substitution of approximately 1 t/ha. Marker-assisted introgression of the superior A7 allele at this locus in the B73 genetic background will not differ from qualitative trait introgression and will eventually lead to new lines having superior testcross performance.
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