Mapping Of Quantitative Trait Loci (qtl) And Genetic Basis For Plant Height And Ear Height In Maize

Plant height and ear height are two important traits for maize. Great attention has been paid to investigate the genetic mechanisms of plant and ear height for increasing planting density and preventing plants from lodging or breaking. To elucidate the genetic basis of the two traits, two F2:3 populations derived from the crosses of Qi319×Huangzaosi and Ye478×Huangzaosi and their testcross populations were materials in the present study. The objectives were to indentify QTL conferring plant height and ear height across multiple environments including different water regimes and estimate their effects; dissect the stability of QTL, the QTL×environment interaction cross environments and the epistatic effects involved in controlling plant height and ear height; and to provide references for effective utilization in maize improvement program. The main results were as follows:1. Stability of QTL across environments and QTL-by-environment interactions for plant height and ear height in maizeTo elucidate the genetic basis of the plant height and ear height, two F2:3 populations derived from the crosses of Qi319×Huangzaosi (Q/H) and Ye478×Huangzaosi(Y/H) with 230 and 235 families, respectively, and their parents were evaluated under three diverse environments in China including Henan, Beijing and Xinjiang in the year of 2007 to 2008. The mapping results showed that a total of 21 and 12 QTL were identified for plant height in the Q/H and Y/H population, respectively, and 24 and 13 QTL for ear height, respectively. Most of the detected major QTL exhibited high stability across different environments. Several major QTL were detected with large and consistent effect under normal condition (bin3.08, bin6.02-6.04 in Q/H), or across two water regimes (bin1.09-1.10,bin8.03 and bin10..03 in Q/H), the major QTL located in chromosome 3 (bin3.04) can be detected in 5 environments in Y/H.2. Correlations and QTL detection in maize line per se and testcross progenies for plant height and ear heightPhenotypic and genotypic correlations between line per se and TC were significant for the cross of Qi319×Haungzaosi and Ye478×Haungzaosi. The QTL analyses showed that several QTLs had large effects and detected for both line per se and TC were found in the present study. The first common QTL for cross of Q/H, located in chromosome 1(bin1.09-1.10), controlling both plant height and ear height, explained 21.6% and 28.3% phenotypic variance for line per se, and 9.5% and 6.8% for TC, respectively.The second common QTL, located in chromosome 8 (bin8.03), controlling both traits, explained very high phenotypic variance for both line per se (33.2% and 45.3%) and TC (14% and 15.9). The third common QTL for Q/H, located in chromosome 10 (bin10.03), controlling ear height, explained 33.3% and 21.8% of phenotypic variance for line per se and TC, respectively. In the cross of Y/H, we found two common QTL, located in chromosome 1 (bin1.09-1.10) and 10 (bin10.03), it was notable that the two QTLs were also the important loci of Q/H. These QTL may be particularly useful in maize breeding programs.