Identification And Analysis Of Quantitative Trait Loci For Drought Tolerance In Maize (Zea Mays L.)

Drought is the most important abiotic factors limiting maize production. The effective approach to solve this problem is breeding and popularizing variety for drought tolerance. However, conventional selection for drought tolerance is inefficient because that drought tolerance is a complicated quantitative trait and required special environment to identify. With the development and application of molecular markers, MAS (molecular assistant selection) supply a useful tool to the breeding for drought tolerance. In order to investigate the molecular genetic basis of drought tolerance and find useful information for genetic improvement to drought tolerance further, molecular marker linkage map was construct with F5 population derived from D5 (drought tolerance)×7924 (drought sensitive) by 120 SSR markers;then 180 F5:6 family lines were identified for drought tolerance under two water regimes(normal control and water stressed);in the end, quantitative trait locus(QTL) associated traits related to drought tolerance were identified and analyzed in this study. The major results are as follows.1. The major traits (grain yield, anthesis-silking interval, plant height, ear height, ear setting) related to drought tolerance of 180 F5:6 family lines were surveyed and analyzed under two water regimes. Under the two water regimes,the average values of all traits are significant difference among family lines, which may be used for QTL mapping; most of these traits are significant positive correlation with yield, but ASI has significant negative correlation with yield. Under water stressed condition, yield and ASI,ear setting may be used for important second drought tolerance indexes.2. A genetic linkage map containing 120 SSR markers was constructed, which spanned a total of 1790.3 cM with an average interval of 14.9 cM. Compared with other published maize linkage maps in chromosome bin locus, the linkage map established in this study was consistent with them. The SSR linkage can be used for QTL mapping.3. By composite interval mapping (LOD>3.0), 28 QTL were detected for 5 traits under two water regime. Under water stress environment, 13 QTL were detected; and under full irrigation environment 15 QTL were detected. Each trait has been identified 2-4 QTLs which were responsible for interpreting 5.39-15.64% of the phenotypic variance individually. QTL of plant height, ear height and ear setting are relatively consistence across two environments.4. This result also show that some QTLs trend to cluster the same chromosome region. The key chromosome regions for drought tolerance mostly lie on the following chromosomes: chromosomel, bnlg1866 (bin1.03); chromosome4, umc1896 (bin4.05) and bnlg1621 (bin4.06); chromosome5, umc1416 (bin5.01); chromosome9, umc2121 (bin9.04).5. Compared the results with other researchers' reports, the chromosome 1 of D5 genomic have higher frequency of QTLs associated drought tolerance.