不同抗性黄瓜品种连作对枯萎病菌群体遗传分化的影响

尖孢镰刀菌黄瓜专化型(Fusarium oxysporum f. sp.cucumerinum,Foc)是引起黄瓜枯萎病的病原真菌，为了明确不同抗性黄瓜品种连作对枯萎病菌遗传分化的影响，本研究采用TEF1-α、H3基因片段对不同抗性黄瓜品种连作及对轮作后分离的枯萎病菌群体进行遗传分化分析。结果表明，感病品种连作及轮作后菌群分化程度较低(0.007ST<0.045);与种植抗病品种一茬后的菌群相比，连作三、五茬后的菌群均发生显著分化(F_ST> 0.050),其中连作三茬后的菌群遗传分化程度最高(F_ST> 0.300)。单倍型分析发现，抗、感病品种连作后部分菌株形成新的单倍型，且分离自抗病品种的病原菌群体分化产生的单倍型数量多于感病品种。主成分分析结果进一步证明，与感病品种连作及轮作相比，抗病品种连作后病原菌菌群呈现出更显著的菌群分化。综上所述，抗病品种连作能够加剧黄瓜枯萎病菌群体的遗传分化。

Effects of continuous cropping cucumber cultivars with different resistance to Fusarium wilt disease on genetic differentiation of population in Fusarium oxysporum f. sp. cucumerinum

Fusarium oxysporum f. sp. cucumerinum (Foc) is the pathogenic fungus causing cucumber Fusarium wilt disease. In order to clarify the effects of continuous cropping cucumber cultivars with different resistance to Fusarium wilt disease on the genetic differentiation of Foc, partial sequences of TEF1-α and histone H3 genes were used to analyze the population differentiation. The results showed that the Foc populations after continuous cropping and rotation cropping of susceptible cultivar presented low level of genetic differentiation (0.007 < F_ST <0.045). Compared with the Foc population after one cycle cropping of resistant cultivar, the Foc populations after three and five cycles cropping of resistant cultivar showed significant differentiation (F_ST > 0.050), with the highest genetic differentiation occurred after three cycles (F_ST > 0.300). Haplotype analyses showed that some isolates from continuously cropped resistant and susceptible cultivars formed new haplotypes. The number of haplotypes including isolates from resistant cultivar was more than that from susceptible cultivar. Furthermore, principal component analyses indicated that in contrast to the Foc populations after continuous cropping or rotation cropping of susceptible cultivar, the Foc populations after continuous cropping of resistant cultivar exhibited more significant genetic differentiation. In conclusion, continuous cropping of resistant cultivars could exacerbate the genetic differentiation of Foc.