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分析赤星病抗性主效QTL的人工选择响应,可为烟草赤星病抗性分子标记辅助选择提供一定的理论基础。本研究利用与主效QTL紧密连锁的分子标记J9和J4,分析随机群体、人工选择群体和自然群体中响应分子标记的等位基因频率,研究相关标记位点在不同群体中的等位基因变化规律。结果发现:(1)赤星病抗性主效QTL等位基因在不同选择强度(5%、10%和20%)的正向选择条件下均发生了显著性偏分离,其中在10%的正向选择强度下偏分离显著性最高。(2)在不同世代(F3、F4、F5和F6)的赤星病抗性育种选择群体中,J9位点抗病亲本等位基因型频率显著高于感病亲本基因型频率,表明来源于抗源净叶黄的主效抗性QTL与赤星病抗性显著关联。(3)在198份自然群体中,包括烟草赤星病抗性品种中烟86、单育二号在内的50份烟草种质携带与抗源净叶黄相同的基因型,表明该主效QTL被广泛应用于烟草赤星病抗性改良中。本研究验证了之前定位到的主效抗病QTL的准确性;分析了该主效QTL的人工选择响应,相关结果为烟草赤星病抗性改良提供了一定的理论基础。
The analysis of the artificial selection response of the major QTLs for the resistance of the brown spot disease can provide some theoretical basis for the molecular marker-assisted selection of brown spot disease resistance. In this study, allele frequencies of response molecular markers in random population, artificially selected population and natural population were analyzed using molecular markers J9 and J4 closely linked to major QTLs to study the allelic changes of the corresponding marker sites in different populations law. The results showed that: (1) The major QTL alleles of brown spot disease had a significant partial segregation under the positive selection conditions of different selection intensities (5%, 10% and 20%), of which 10% positive Selective separation of the highest intensity under the partial intensity. (2) The frequencies of alleles of J9-resistant parents were significantly higher than those of susceptible parents in the breeding populations of different generations (F3, F4, F5 and F6) The QTLs for net net leaf yellowing were significantly associated with resistance to brown spot disease. (3) Among the 198 natural populations, 50 tobacco germplasm including tobacco brown spot resistant varieties Zhongyan 86 and Danyu 2 carried the same genotype as the resistant net leaf yellow, indicating that the main effect QTL Is widely used in tobacco brown spot disease resistance improvement. This study validated the accuracy of QTLs for major disease resistance previously identified and analyzed the artificial selection response of QTLs for major QTLs. The results provide a theoretical basis for the improvement of resistance to R. tabaci.