Genetic Mapping Of QTL About Waterlogging Tolerance In Maize Seedings (Zea Mays L.)

Maize is one of the most important food crops in the world. In tropical and subtropical regions, severe crop losses are always caused by prolonged seasonal rainfall. Waterlogging is also a serious environmental stress on maize grown at maize seedling stage in southeastern China. To take the consideration of the fine mapping based on couple hundreds population with linkage disequilibrium analysis, QTL of traits associated waterlogging response were identified through candidate-based association mapping performed using96maize inbred lines, and GWAS (genome wide association study) done with56110SNP using144maize inbred lines. At the same time, QTL of traits associated waterlogging response was further proved using a BC2F2:3linkage mapping. The main results were as following:1. Candidate-gene-association mapping was conducted based on the candidates zmbRLZ and Hemoglobin through Eco TILLING in a population comprised by96maize inbred lines.33SNP were found in the region of zmbRLZ though sequencing, and10SNP were identified with MAF>5%. Some of the10SNP showed significant correlation and5of them may stand for most of the genetic diversity. One of SNP was significantly associated with the waterlogging responsive trait in the level of0.005. Another two SNP were significantly associated with the waterlogging responsive trait in the level of0.05..2. Out of825624(45868SNP×9traits×2environments) possible associations, two associations (PUT-163a-93013517-4810bin9.07, PZE-105105668bin5.04) were identified through GWAS in the population of144maize inbred lines, which significantly associated with RFW (root fresh weight) in the normal condition and SFW (shoot fresh weight) under waterlogging (p<2.18X10-6), respectively;27associations were identified (p<2.18×10-5) for5SNP;141associations were identified (p<2.18×10-4) for53SNP.3. Secondary traits, WTC (waterlogging coefficient) and index of yellow leaf were estimated and mapped by GWAS with45868SNP. Consensus results were found on chromosome1for various WTC (p<2.18×10-5), which included3different loci. Negative result existed for index of yellow leaf through GAWS with45868SNP. And LD analysis with haplotype for index of yellow leaf revealed unique locus(N4590bin6.05) significantly associated with index of yellow leaf.4. The significant loci identified through GWAS were further verified by linkage analysis. The bin5.04-5.06is included by the QTLs confidence interval and several QTLs located in bin9.06-9.07. It deduced that two significant SNP may be positive association loci. Predicted candidates are involved in various molecular functions, suggesting that they are important region for biological events.