黄瓜抗霜霉病异源易位系CT201的筛选与鉴定

 将栽培黄瓜‘北京截头’ (Cucumis sativus L. , 2n = 14) 与Cucum is属双二倍体新种C. hytivus (2n = 38) 回交, 随后自交。通过霜霉病田间接种试验筛选, 从中发现抗霜霉病单株HH12825。将HH12825与C. hytivus的原始亲本‘北京截头’和野生种C. hystrix进行农艺性状对比观察, 发现此单株在叶面积、节长、果长×果径等方面介于栽培黄瓜和野生种之间, 在侧枝数、果刺颜色等方面偏向野生种。观察其花粉母细胞减数分裂过程, 发现其PMC中期Ⅰ多价体频率(56% ±8% ) 和后期Ⅰ二价体分离滞后率(72% ±5% ) 都较高, 具有染色体易位的细胞学特征。进一步利用RAPD分子标记分析, 结果在40个随机引物中找到了两个引物( E219: ACGGCGTATG和A I220: CCTGTTCCCT) 能够在HH12825中重复地扩增出原始亲本野生种C. hystrix特异DNA片断, 从分子水平上证明了其为黄瓜异源易位系, 并把此易位系命名为CT201。

Identification and Characterization of a Cucumber Alien Translocation Line CT-01 Possessing Resistance to Downy Mildew

Cultivated cucumber‘Beijing Jietou’ (Cucumis sativus L. , 2n = 14) was backcrossed to the synthetic amphidiploid species C. hytivus (2n = 38) , and the progenies were selfed. All the plants were tested for downy mildew resistance by field inoculation. One plant HH12825 possessing resistance was identified in the BC₁ F₂ population. The HH12825 was compared with the cucumber and the wild Cucum is species C. hystrix in morphology and cytology. The result indicated that some of its morphological characters were intermediate between the two parents, e.g. , leaf area, internodeps length, and fruit length ×diameter, while some of them were closer to the wild species, e.g. , number of lateral branches, fruit spines color. In cytology, observations from meiotic process indicated much higher frequencies of multivalents (56% ±8%) atmetaphase I and chromosome lagging rate (72% ±5%) at anaphaseⅠ in the pollen mother cell ( PMC) , indicating typical behavior of a translocation plant. Random amplified polymorphic DNA (RAPD) analysis was carried out with the genomic DNAs of HH12825. Two p rimers E219: ACGGCGTATG and A I220: CCTGTTCCCT from 40 random primers selected could amplify a special repeatable DNA sequence from C. hystrix in the plant and thus its translocation nature was confirmed, and its was named as CT201, thereafter.