Construction Of The Genetic Linkage Map Of Sorghum And The Primary QTL Mapping Of Some Important Agronomic Traits

Sorghum, as an important forage plant and main grain crop which spread broadly in the arid or semi-arid tropics, is the fifth most important cereal crop worldwide after wheat, rice, maize and barley. Sorghum genome with its relatively small genome type and genetic diversity is becoming the model Genome in cereal crops’comparative genomics researching. Meanwhile, as an important nonfood energy crop, it also becomes widely appreciated in the exploration of renewable sources of energy. Many crops have been obtained high-density molecular genetic maps and located the main QTLs of many agronomic traits using molecular markers.In this study, a recombinant inbred population (Recombinant Inbred RI) of sorghum, constructed from the two parents T70and P607, are used for constructing a genetic linkage map, and the QTLs of many important agronomic traits, such as plant height, flowering, yield and other traits were localized by using the new methods of quantitative genetics or Molecular Marker Techniques (Analysis of121pairs of SSR primers for screening polymorphic of the genome, then, Mapmaker3.0software for linkage analysis and construction of genetic linkage map. WindowsQTL Cartogragpher2.5software and methods of composite interval mapping were used to verify sorghum important agronomic traits QTL location and QTL effects of phenotypic traits.) The main results were as follows:1) From the descriptive statistical analysis of phenotypic data, we found most traits nearly complied with the normal distribution apart from tiller, so they can used to construct the genetic linkage map. 2) We analyzed the polymorphic of the F6RIL population consisting of218individuals with121pairs of SSR primers. We constructed a genetic linkage map spanning541.9cM based on a total of24simple sequence repeat (SSR) markers, and the average distance of loci was17.5cM. This map consist seven linkage groups which located on five chromosomes.3) QTL analysis for nine agronomic traits was studied using the WindowsQTL Cartogragpher2.5software. A total of15QTLs were detected which were interrelated with the nine traits of plant height, length of spike, length of shank, pitch number of stem, number of branch, stem height, days of flag leaf, days of flowering, days of growth period, respectively. But only three QTLs’LOD values were above2.5which interrelated with the plant height.The molecular genetic linkage map and QTLs localization of important agronomic traits in sorghum constructed in this study will provide the basis for fine mapping of the main effect QTLs and molecular marker-assisted breeding. QTLs obtained with traits of plant height have theoretical significance for breeding of new variety.