Study On QTL Mapping For Drought Tolerance During Seed Germination And Seedling In Maize

Maize is the third most improtant crop worldwide. In most maize-growing area, drought is by far the leading environmental stress causing yield reductions. Breeding for drought tolerance (DT) via gentic means is becoming a key aspect. Seed germination and early seedling growth is the beging stage for maize development. The ability of the seed to germination rapidly and uniformly under drought stress (DS) is a desirable trait for maize production. Maize response to DS is controlled by polygenes and is highly influenced by environmental variation. With SSR and many molecular marker mathods developed, it is possible to map DT related QTLs and make further analysis. In this study, a F₉RIL (recombinant inbred line) with 101 individuals, derived from a stress-tolerant Mo 17 and a stress-sensitive Huangzaosi, is used to construct a genetic map and located drought related QTLs. The results are as follows:1. A total of 370 microsatellite (SSR) markers cover 10 maize chromosomes were chosen to screen the parental lines Mol7 and Huangzaosi for polymorphism. 101 SSR markers were placed on a framework with program Mapmaker version 3.0b and spanned 1422.7 cM, the RIL map has an average SSR marker density 15.6 cM. The marker order was quite consistent and in agreement with published IBM map. So the map can be used to locate QTLs.2. Method of CIM (composite Interval Mapping) of program Windows QTL Cartographer version 2.0 was used to scan QTLs with intervals of 2 cM between markers and putative QTLs, and with a window size of 10 cM. Meanwhile the genetic effects of putative QTLswere analyzed.3. 3 quantitative trait loci (QTLs) for germination stress index (GSI) under DS were detected. Of these, one QTL located on chromosome 1, linked with marker umc1358, was contributed by Mo17 donor parent, the additive effect was 1.47%. which can explained 49.37% of the phenotypic variance, other two QTLs, located on chromosome 5 and 10, linked with marker bnlg1006 and phi050, were contributed by Huangzaosi donor parent, the additive effects were -1.50% and -1.40%. which can explained 50.53% and 44.46% of the phenotypic variance, respectively.