QTL Mapping for Plant Height in the CML52 × B73 Maize RIL Subpopulation: Insights from a Nested-Association Mapping Approach

Plant height is one of the key agronomic traits used as a variable to model vegetative and developmental growth in crops. It is one of the most salient yet important yield-associated traits that could be utilized in breeding against lodging effects in the maize breeding program. A RIL subpopulation derived from the cross between parental lines, CML52 x B73, from a nested association mapping (NAM) population genotyped with SNP markers for approximately thirty-seven (37) traits was used to identify QTL for plant height. A genetic linkage covering all 10 chromosomes was constructed, and the QTLs affecting plant height were mapped and analyzed by single marker analysis (SMA), interval mapping (IM), and composite interval mapping (CIM) at a LOD score of 3.11, 3.14, and 6.11, respectively. Six (6) QTLs for plant height detected were located at different regions of five chromosomes (2, 6, 8, 9, and 10). The results showed that there were different effect values of QTL on plant height estimated by the different techniques. The percentage of phenotypic variation of single-QTL to plant height varied from 6.49% to 10.24% using IM and 4.14% to 9.16% using CIM. The multiple-QTL estimated an overall phenotypic variation of 17.25% using IM and 22.07% using CIM. Since the CIM detected the highest number of putative QTLs, it can be widely adopted for QTL mapping analysis. The two QTLs, c9.loc93 (chr.9 pos. 93), being consistently identified by most of the techniques, and PZA03728.1 (chr.10 pos. 65.1), having the highest phenotypic variation (10.24%), could be considered in a maize breeding program to lower the lodging effect on taller maize plants.