甜瓜属人工异源四倍体(Cucumis hytivus)染色体组间重组的 细胞学及分子标记研究

 采用细胞学和分子标记方法对甜瓜属人工异源四倍体（C. hytivus Chen and Kirkbride，2n = 4x = 38）的亲本染色体组间的交换重组进行了研究。通过对减数分裂中期I染色体行为观察，在108个花粉母细胞中有50个细胞具有多价体，占46.3%，染色体的平均构型为0.56I+17.36II+0.35III+0.26IV+0.046V+0.056VI，表明两亲本染色体组间发生了广泛的重组交换。通过对446条随机引物进行筛选，有5条引物扩增出6条C. hytivus特征带。选取其中3条转换成SCAR标记，对13种甜瓜属不同基因型材料的DNA进行扩增，结果仅有SAP-03/700标记表现为特异性。进一步分析这一标记在人工异源四倍体（C. hytivus）、栽培黄瓜（C. sativus var. sativus）及野生黄瓜（C. sativus var. hardwickii）中扩增出的3条不同分子量条带序列，发现两端序列较为一致，中间部分不同，与黄瓜线粒体基因组序列有200 bp左右的大小相同，但方向相反。

Cytological and Molecular Studies on Genomic Exchange and Reconstitution in the Synthetic Allotetraploid Cucumis hytivus

The exchanges and reconstitutions between the two genomes in the allotetraploid Cucumis hytivus Chen & Kirkbride (2n = 4x = 38) were investigated by cytological and molecular means. Among the 108 pollen mother cells (PMC) observed, 50 PMC (about 46.3%) had multivalents, indicating the wide genomic exchange and reconstitution. The average chromosome configuration was 0.56I+17.36II+0.35III+0.26IV+0.046V+0.056VI. Among 446 arbitrary primers, only 5 primers could produce 6 specific bands of C. hytivus. Three of them were selected and converted into sequence characterized amplified region (SCAR) markers. The SCAR markers were used in amplification with 13 Cucumis genotypes, and the results showed that only SAP-03/700 marker was specifically amplified. Compared the sequence of 3 different bands amplified by SAP-03/700 primer pair in C. hytivus, C. sativus var. sativus and C. sativus var. hardwickii, the sequences at 2 ends were similar while the middle parts were different. In addition, about 200 bp of SAP-03/700 was homologous with cucumber mitochorndrial genome, but the directions were contrary.