USING GENETIC DIVERSITY OF IMPROVE QUANTITATIVE DISEASE RESISTANCE AND AGRONOMIC TRAITS OF CORN
Location: Plant Science Research
Title: Genetic Control of Photoperiod Sensitivity in Maize Revealed by Joint Multiple Population Analysis
Submitted to: Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 8, 2009
Publication Date: March 10, 2010
Citation: Coles, N.D., McMullen, M.D., Balint Kurti, P.J., Pratt, R.C., Holland, J.B. 2010. Genetic Control of Photoperiod Sensitivity in Maize. Genetics. 184:799-812.
Interpretive Summary: Maize is very diverse genetically, but much of this diversity exists in maize from tropical regions of the world, such as Latin America. Tropical maize is highly sensitive to photoperiods and often will not flower at an appropriate time in the USA corn growing region. To better access the genetic diversity of tropical maize, it will help breeders to understand the genetic basis of this response. We mapped gene regions that affect the photoperiod response in maize and found four major gene regions that control photoperiod sensitivity, plus a number of other smaller effect genes throughout the genome. We found that different tropical maize lines may carry different genes for photoperiod response.
Reduced photoperiod sensitivity was critical to the evolution of broad geographical adaptability in maize, but modern tropical maize retains photoperiod sensitivity, hindering its use in temperate maize breeding programs. Many flowering time genes have been identified in diverse plant species, but their relationship to natural variation for photoperiod response in maize is unknown. Forward and reverse genetic approaches were combined to evaluate the functional allelic variation of candidate genes on photoperiod sensitivity among diverse maize lines. Candidate gene sequences were mapped directly and indirectly on four recombinant inbred line (RIL) populations created from a factorial mating of two temperate inbred lines to two photoperiod-sensitive tropical inbreds. Whole-genome scans were also conducted by high-density genotyping of the RIL populations, which were phenotyped over three years in both short- and long-day environments. Joint multiple population analysis identified genomic regions controlling photoperiod responses in flowering time, plant height, and total leaf number. These regions encompassed candidate genes CONZ1, CRY2, ELF4, VGT1, HY1/SE5, PRR7/PPD-1, PIF3, ZCN5, and ZCN19. Four key genome regions strongly affected photoperiod response across multiple populations, but functional allelic differences within these regions among phenotypically similar founders suggest distinct evolutionary trajectories for photoperiod adaptation in maize.