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根肿病是影响大白菜生长发育及其产量的一个重要病害。本研究在前人定位出抗根肿病QTL QS_B3.1的基础上,以相同的抗根肿病芜菁自交系‘Siloga’为供体亲本,大白菜自交系‘91-12A’为受体亲本,通过对回交和自交群体的分子标记前景和背景选择,从BC4F3群体中筛选出遗传背景恢复为‘91-12A’,且只含有QS_B3.1位点的大白菜近等基因系。对BC4F3群体进行根肿病抗性鉴定,抗病植株与感病植株的分离比例为3:1,证明QS_B3.1抗病位点表现为显性单基因遗传。BC4F3群体的QS_B3.1连锁标记分析表明,抗病植株均含有QS_B3.1位点,不含QS_B3.1位点的植株均表现为感病,且QS_B3.1位点缩小在A3染色体的一个2.89 Mb区间内。这一发现为今后芸薹属作物的抗根肿病品种的选育以及该基因的精细定位和克隆提供了有力的依据。
Clubroot disease is an important disease affecting the growth and yield of Chinese cabbage. In this study, QTL QS_B3.1 was constructed based on the previous study on QS_B3.1 resistant to clubroot disease. The same inbred line ’Siloga’ resistant to clubroot disease was used as donor parent. The inbred line ’91 -12A ’was Recipient parents were selected from the BC4F3 population by screening the foreground and background of the molecular markers for backcrossing and selfing populations. The Chinese cabbage near-isogenic line with the QS_B3.1 locus recovered to ’91 -12A ’ system. The clubroot resistance of BC4F3 population was identified. The segregation ratio of resistant plants to susceptible plants was 3: 1, which proved that QS_B3.1 showed dominant single-gene inheritance. QS_B3.1 linkage analysis of BC4F3 population showed that the resistant plants all contained the QS_B3.1 locus, the plants lacking the QS_B3.1 locus showed susceptible disease, and the QS_B3.1 locus narrowed down to a 2.89 locus on the A3 chromosome Mb interval. This finding provides a strong basis for the breeding of the disease-resistant clubhead cultivars in Brassica crops and the fine mapping and cloning of the genes in the future.