Khalid A. Osman^{1, 2}, Bin Tang¹, Fazhan Qiu¹, Ahmed M. El Naim^3,

Waterlogging strongly affects agronomic performance and yield of maize. In order to investigate the genetic basis of maize seedling response, remapping of the majors quantitative trait loci (QTL) associated with waterlogging tolerance (WT) related traits were subjected, including plant height, root length, shoot fresh weight, root fresh weight, root dry weight, shoot dry weight, total dry weight, during maize seedling stage by using advanced backcross QTL (AB-QTL) analysis approach in a mixed linear model and inclusive composite interval mapping method under waterlogging and control conditions. A 266 BC₂F₂ population derived from a cross between a waterlogging-tolerant line ‘HZ32’ and a susceptible line ‘K12’ was used. A new linkage map constructed, consisting of 167 polymorphic SSR markers, spanned 1797.6 cM in length across a maize genome, with an average distance of 10.8 cM between adjacent markers. A total of 44 and 25 putative QTLs were detected under waterlogging treatment and control conditions, respectively. These QTLs were distributed over all 10 chromosomes, and had LOD scores ranging from 2.58 to 14.74, explaining 3.46 to 24.37% phenotypic variation in the individual traits. Out of which, thirty one major QTLs individually accounted for more than 10% of the phenotypic variation; they were governed traits associated with RL, PH, SDW, RDW, TDW and RFW were mapped in the different genomic region on chromosomes 1, 2, 3, 4, 6, 7 and 9. The results reveal that the former major QTL mapped by AB-QTL, could be selected in backcross population for fine mapping of waterlogging tolerance. The results also may provide new insight into the molecular basis of the waterlogging response of seedlings stage and useful markers for MAS and further genetic studies on maize waterlogging tolerance.

AB-QTL mapping, Maize (Zea Mays), SSR marker, MAS, waterlogging stress