Stability of QTL Across Environments and QTL-by-Environment Interactions for Plant and Ear Height in Maize

Better understanding of genotype-by-environment interaction (GEI) is expected to provide a solid foundation for genetic improvement of crop productivity especially under drought-prone environments. To elucidate the genetic basis of the plant and ear height, 2 F2:3 populations were derived from the crosses of Qi 319 × Huangzaosi (Q/H) and Ye 478 × Huangzaosi (Y/H) with 230 and 235 families, respectively, and their parents were evaluated under 3 diverse environments in Henan, Beijing, and Xinjiang, China during the year of 2007 and 2008, and all the lines were also evaluated under water stress environment. The mapping results showed that a total of 21 and 12 QTLs were identified for plant height in the Q/H and Y/H population, respectively, and 24 and 13 QTLs for ear height, respectively. About 56 and 73% of the QTLs for 2 traits did not present significant QTL-by-environment interaction (QEI) in the normal joint analyses for Q/H and Y/H population, respectively, and about 73% of the QTLs detected did not show significant QEI according to joint analyses for stress condition in Q/H. Most of the detected major QTLs exhibited high stability across different environments. Besides, several major QTLs were detected with large and consistent effect under normal condition (Chr. 6 and 7 in Q/H; Chr. 1, 3 and 9 in Y/H), or across 2 water regimes (Chr. 1, 8 and 10 for in Q/H). There were several constitutive QTLs (3 for Q/H and 1 for Y/H) with no or minor QTL-by-environment for the 2 populations. Finally, we found several genomic regions (Chr. 1, 10, etc.) to be co-located across the populations, which could provide useful reference for genetic improvement of these traits in maize breeding programs. Comparative genomic analysis revealed that 3 genes/genetic segments associated with plant height in rice were orthologous to these 3 identified genomic regions carrying the major QTLs for plant and ear height on Chr. 1, 6, and 8, respectively.