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 x 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.