Genetic Analysis And QTL Mapping Of Dwarf And Compact Spike Mutant Of Sumai 3

A dwarf and compact spike mutant H164 was obtained from Sumai3 treated with chemical mutagen Ethyl methane sulfonate (EMS).The average plant height of H164 is 50cm, which is only half of that of Sumai3. The shorted plant height of this mutant is mainly due to the decrease of internode length. The average spike density of H164 is 4.3/cm, and it compacter spike is mainly due to the decrease of spike length. In the seedling stage, H164 was sensitive to exogenous gibberellin acid (GA3), and the content of endogenous gibberellin acid (GA3) in leaves of H164 is significantly lower than that of Sumai3 at their elongation stage.In order to study the genetic mechanism of the dwarf and compact spike characters, F2 and F2:3 populations were constructed derived from the cross of H164×Sumai3. The result indicated that, the dwarf character in H164 was controlled by a partial dominant gene, and the spike density was controlled by a completely dominant gene.Using another F2 population derived from the cross of H164xAlondra's, a molecular marker based linkage map was constructed and QTLs related to plant height and spike density were identified. A total number of 908 primer pairs (including SSR and EST-SSR) located on 21 wheat chromosomes were employed randomly to reveal the polymorphism between the two parents. Two hundred and seven primer pairs were found to be polymorphic, and the polymorphic rate was 22.80%. Ninety-eight polymorphic primers, which could amplify clear and stable DNA bands, were further used for amplification in the 283 F2 individuals,χ2 analysis revealed that 9 markers were skewed segregated in the population, account for 9.18%.The amplification data of 89 polymorphic primers in the population were futher used for linkage analysis using the Joinmap4.0 soft. A genetic map consisting of 28 linkage groups were constructed. The map covered a total of 1524.5cM of wheat genome and the average genetic distance was 17.10cM. According to the reported chromosome location of the analyzed molecular markers, these 24 linkage groups belonged to the 19 of the 21 wheat chromosomes, except chromosomes 4D and 6D.Based on the constructed genetic map, QTL analysis was performed using a joint composite interval mapping method of the Windows QTL Cartographer 2.5 software. One QTL related to the plant height was detected on chromosome 2D at the marker interval of Xwmc112-Xwmc503, its contribution ratio was 11.24%. One QTL related to spike density was also detected on chromosome 2D at the marker interval between Xwmc453-Xwmc112, its contribution ratio was 5.52%.