Mapping of QTL associated with waterlogging tolerance during the seedling stage in maize

Abstract

Background and aims: Soil waterlogging is a major environmental stress that suppresses maize (Zea mays) growth and yield. To identify quantitative trait loci (QTL) associated with waterlogging tolerance at the maize seedling stage, a F2 population consisting of 288 F(2:3) lines was created from a cross between two maize genotypes, 'HZ32' (waterlogging-tolerant) and 'K12' (waterlogging-sensitive).

Methods: The F2 population was genotyped and a base-map of 1710.5 cM length was constructed with an average marker space of 11.5 cM based on 177 SSR (simple sequence repeat) markers. QTL associated with root length, root dry weight, plant height, shoot dry weight, total dry weight and waterlogging tolerance coefficient were identified via composite interval mapping (CIM) under waterlogging and control conditions in 2004 (EXP.1) and 2005 (EXP.2), respectively.

Key results and conclusions: Twenty-five and thirty-four QTL were detected in EXP.1 and EXP.2, respectively. The effects of each QTL were moderate, ranging from 3.9 to 37.3 %. Several major QTL determining shoot dry weight, root dry weight, total dry weight, plant height and their waterlogging tolerance coefficient each mapped on chromosomes 4 and 9. These QTL were detected consistently in both experiments. Secondary QTL influencing tolerance were also identified and located on chromosomes 1, 2, 3, 6, 7 and 10. These QTL were specific to particular traits or environments. Although the detected regions need to be mapped more precisely, the findings and QTL found in this study may provide useful information for marker-assisted selection (MAS) and further genetic studies on maize waterlogging tolerance.

Fig. 1.

Molecular linkage map of the F₂ population derived from a cross between ‘HZ32’ and ‘K12’, and summary of QTL for all traits responsive to waterlogging in the mapping population of maize in EXP.1 and EXP.2. sdw = shoot dry weight; ph = plant height; rl = root length; rdw = root dry weight; tdw = total dry weight. For all the QTL names, the first number following the letters represents the chromosome locations of the QTL and the second number represents the orders of the QTL located on the same chromosome by the same trait. The distances between markers (cM) are listed to the left of each figure part.

Fig. 1.

Molecular linkage map of the F₂ population derived from a cross between ‘HZ32’ and ‘K12’, and summary of QTL for all traits responsive to waterlogging in the mapping population of maize in EXP.1 and EXP.2. sdw = shoot dry weight; ph = plant height; rl = root length; rdw = root dry weight; tdw = total dry weight. For all the QTL names, the first number following the letters represents the chromosome locations of the QTL and the second number represents the orders of the QTL located on the same chromosome by the same trait. The distances between markers (cM) are listed to the left of each figure part.

Fig. 1.

Molecular linkage map of the F₂ population derived from a cross between ‘HZ32’ and ‘K12’, and summary of QTL for all traits responsive to waterlogging in the mapping population of maize in EXP.1 and EXP.2. sdw = shoot dry weight; ph = plant height; rl = root length; rdw = root dry weight; tdw = total dry weight. For all the QTL names, the first number following the letters represents the chromosome locations of the QTL and the second number represents the orders of the QTL located on the same chromosome by the same trait. The distances between markers (cM) are listed to the left of each figure part.