| A high-tillering, dwarf mutant H167 was identified from an EMS-mutagenised population of wheat variety Wangshuibai. The number of effective tillers and plant height of the matant are 26±6.1 and 64.1±6.8cm. Compared with its wildtype, the decrease of plant height of H167 is mainly due to the decrease of internode length. At the seeding stage, H167 is sensitive to exogenous gibberellins acid (GA3). At the elongation stage, the endogenous GA content of H167 was significantly higher than that of Wangshuibai both in the leaf and root tissues. The deficiency of the biosynthesis of gibberellins acid (GA3) may be one of the important reseason of the dwarf phenotype of the mutant. Removal of the axillary buds failed to recover the plant height of the mutant to the wildtype, indicating that the decrease of the plant height is not the result of the increase of tillers.In order to study the inheretance of the tiller and dwarf traits, a F2 derived from the cross of H167×Sumai 3 was constructed. Genetic analysis using the 'major gene-polygene mixed inheritance models'showed that both effective tillers and plant height in the population were controlled by two major genes with additive-dominance-epistatic effects plus poly-genes, with their major-gene heritability being 57.72% and 73.14%, respectively.Using the H167×Sumai 3 F2 population, a molecular marker based linkage map was constructed and QTLs related to effective tillers and plant height were identified. A total number of 1529 primer pairs (including SSR and EST-SSR) located on 21 wheat chromosomes were selected randomly, and used for polymorphism analysis between the two parents. Two hundred and five primer pairs were found to be polymorphic, and the polymorphic rate was 13.4%. One hundred twenty-six polymorphic primers, which could amplify clear and stable DNA bands, were further used for amplification in the F2 individuals. Theχ2 analysis revealed that 49 markers were skewed segregated in the population.The amplification data of the above 126 polymorphic primers in the population was further used for linkage analysis using the Joinmap 4.0 software. A genetic map consisting of 31 linkage groups was constructed. The map covered a total of 1185.5cM of the wheat genome and the average genetic distance was 12.48cM. According to the reported chromosome location of the analyzed molecular markers, these 31 linkage groups belonged to the 19 of the 21 wheat chromosomes, except chromosomes 4B and 4D.Based on the constructed genetic map, QTL analysis was performed using a joint composite interval mapping method of the Windows QTL Cartographer 2.5. Four QTLs related to effective tillers were detected, two were on chromosome 3B, their contribution ratio was 10.58% and 4.48%:one was on chromosome 2A. its contribution ratio was 6.45%; one was on chromosome 7B. its contribution ratio was 6.44%. Three QTLs related to plant height were detected on chromosome 3B, their contribution ratio were 7.45%,8.05% and 8.07%, respectively。... |
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