|Coles, Nathan -|
|Zila, Charles -|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 11, 2011
Publication Date: May 1, 2011
Citation: Coles, N., Zila, C., Holland, J.B. 2011. Functional Allelic Variation at Key Photoperiod Response QTL in Maize. Crop Science. 51:1036-1049. Interpretive Summary: Tropical maize represents a valuable genetic resource containing unique genes not present in USA Corn Belt maize. The strong delay in flowering in response to long daylength photoperiods exhibited by most tropical maize hinders its incorporation into USA maize breeding programs. We validated four important gene regions affecting flowering time photoperiod response identified previously and tested in independent studies here. We also showed that different tropical lines carry genes with different effects on flowering time; some tropical lines carry versions of these genes that do not cause later flowering. A major photoperiod gene on chromosome 10 was precisely located to a small chromosomal region.
Technical Abstract: Tropical maize represents a valuable genetic resource containing unique alleles not present in elite temperate maize. The strong delay in flowering in response to long daylength photoperiods exhibited by most tropical maize hinders its incorporation into temperate maize breeding programs. We tested the hypothesis that diverse tropical inbreds carry functionally similar alleles at four key photoperiod response QTL previously identified in maize. Four tropical maize inbreds were each crossed and backcrossed twice to the temperate recurrent parent B73 to establish four sets of introgression lines. Evaluation of these lines under long daylengths demonstrated that all four QTL have significant effects on flowering time or height in these lines, but the functional allelic effects varied substantially across the tropical donor lines. At the most important photoperiod response QTL on chromosome 10, one tropical line allele even promoted earlier flowering relative to the B73 allele. Significant allelic differences among tropical founders were also demonstrated directly in an F2 population derived from the cross of Ki14 and CML254. The chromosome 10 photoperiod response QTL position was validated in a set of heterogenous inbred families evaluated in field tests and in controlled environments.