Submitted to: Plant and Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: 11/1/2004
Publication Date: 1/12/2005
Citation: Frost, J., Snook, M., Houchins, K.E., Rector, B.G., Widstrom, N.W., Mcmullen, M.D. 2005. The genetic basis of recurrent selection gains for maysin in maize silks [abstract]. Plant and Animal Genome Conference. p. 395.
Technical Abstract: Recurrent selection is a standard procedure used by plant breeders to increase favorable alleles for a desired trait in a population, however, the genes underlying the selection gain are generally unknown. Breeders in Tifton, Georgia, conducted eight cycles of recurrent selection in two populations for high levels of maysin, a C-glycosyl flavone in silks that confers resistance to the corn earworm. The two populations are EPM (exotic populations of maize) and SIM (southern inbreds of maize). Silks from inbred lines derived from cycle 6 of the EPM population (EPMC6S8) and cycle 5 of the SIM population (SIMC5S8) had maysin values of 3.4 and 1.5% fresh silk weight, respectively. To address the question of what genes underwent selection to result in gains to such high levels of maysin, three quantitative trait locus (QTL) populations were analyzed using EPMC6S8, SIMC5S8, and GT119 (a low maysin inbred) as parental lines. The QTL detected have similar locations to the previously reported candidate genes p, whp1, c2, and in1. The p gene encodes the main transcription factor of the flavonoid pathway and chalcone synthase, which synthesizes the first committed step of the flavonoid pathway is encoded by c2 and whp1. The intensifier gene (in1) is believed to regulate whp1 expression. Real time RT-PCR is being utilized to confirm these candidate genes in the (EPMC6S8 x GT119)F2 population. Our experiments suggest that recurrent selection worked to increase the levels of maysin by accumulating favorable alleles of both regulatory and structural genes in the flavonoid pathway.