Mapping QTLs For SSR Marker Genetic Mapping And Tiller Number Of Wheat Constructed From High - Generation Inbred Lines

Most of the traits about wheat yield are controlled by quantitative trait locus (QTL), whose research is very complicated. Tiller is one of the most significant traits which affect the wheat yield. Meanwhile tiller is the important index of field management and basic characteristic of wheat growth. It’s very necessary and valuable to study the genetic basis of tiller of wheat by relative high technologies. In this study, there are 430 RIL population that are created by two translocation lines CN18 and T1208 as the parents. Since Dec.6th,2014 to January 22nd,2015, do field investigation and record every two weeks. Use SSR molecular marker to construct the corresponding genetic linkage map, then locate and analysis QTLs of wheat tiller. The main results are as follows:1. According to the field investigation data, the average number of tillers between two parents is different, and the parent CN18 is more than T1208. The average number of tillers of RIL population is less than two parents.Tiller number variation between families in RIL population reaches extremely significant level with high CV. The distribution of tiller number in RIL population is continuous and the transgressive segregation is obvious. The absolute value of kurtosis and skewness in RIL population is less than 1.0, which proves that the distribution of tiller number in RIL population fits normal distribution. The results show that the tiller trait of wheat is quantitative trait and the RIL population can be used to construct the corresponding genetic linkage map.2. Two parents, CN18 and T1208, were screened for polymorphism with 1075 SSR markers, and 103 markers were polymorphic between the parents. The frequency of polymorphism was 9.6%. Finally,52 markers were mapped on 17 chromosomes of wheat with software QTL IciMapping 3.0. Those markers covered 1215.45cM of the whole wheat genome with an average genetic distance of 27.6cM.3. The QTL analysis was performed with the software QTL IciMapping 3.0 based on Inclusive Composite Interval Mapping (ICIM) with LOD thresholds of 2.0. A total of 16 putative QTLs for wheat tiller trait were detected. These were located on chromosomes 1B、2A、2B、2D、3B、4A、4B、5D、6A、6B、6D、7Aand 7D, explaining 2.61%～55.63% of the phenotypic variance, respectively. In all, those QTLs detected at the same time in three different periods were located on chromosomes 1B、2A、2B、2D、3B、4A、4B、6D、7A and 7D.4. Some QTLs were detected in one or two different periods. Those QTLs detected at the same time in three different periods also showed out difference: the PVE(%) of some QTLs was increasing such as QTLs located on 1B、2B、2D、3B、 4A、6D and 7D; on the contrary, the PVE(%) of some QTLs was reducing, for example QTLs located on 3B、4B and 7A. The variance of PVE(%) was significant. According to those dates, the author doubt that the QTLs of wheat tiller expressed dynamically with temporal specificity. The definite result needs more dates and intensive study to confirm.