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Applying segregation distortion approach in QTL analysis of three non-BSSS doubled haploid populations in maize

Three biparental populations of doubled haploid (DH) maize lines (Os2702, Os2703 and Os2709) derived by in vivo haploid induction technique from crosses of five maize dent non-BSSS (stiff stalk) inbred lines were studied for flowering time. We applied novel method for QTL mapping via segregation distortion based on generalized linear mixed model in multiple breeding populations requiring no large population sample. Population sizes ranged from 33 individuals (Os2702) to 68 individuals (Os2703). The populations were genotyped by using the Illumina MaizeSNP50 BeadChip. Across all three populations, distorted markers were observed on all chromosomes, but certain chromosome regions were more affected than others. We focused on a segregation distortion region (SDR) on chromosome 3 (bin 3.9) detected by significant joint Wald test statistics in all three DH populations. SNP markers with the most extreme segregation distortion in the SDR in respective populations were associated with anthesis calculated as growing degree days (GDD). In average, GDD from emergence to anthesis were 785, 800 and 808 in three populations respectively. However, the SDR was mapped nearby to the known gametophyte factor ga7 suggesting that the factor may be a genetic reason for segregation distortion. Our further investigations on other SDRs of the maize genome might elucidate the effectiveness of QTL mapping by detecting segregation distortion.

Doubled haploids ; segregation distortion ; QTL analysis ; maize

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