六倍体小黑麦和八倍体小偃麦杂交F_2的细胞学特性

Cytological Characteristics of F_2 Hybrids Derived from Triticale(2n=6x=42)×Trititrigia(2n=8x=56)

以八倍体小偃麦(远中1号、远中3号和远中5号)与六倍体小黑麦杂交,对F2的形态学及细胞学特性进行了研究,以期为创造小麦-偃麦草-黑麦异位新种质奠定基础。结果表明,3个组合F2自交结实率分别为28.11%、41.11%、39.92%。不同组合根尖细胞染色体数目变化分别有8、12、29种类型,组合间染色体数目分别在46～58、49～60、34～64条变异。花粉母细胞减数分裂染色体行为异常,组合间平均每个细胞单价体数基本相当,分别为10.45、11.60和11.69。组合远中1号/兰考小黑麦和远中3号/兰考小黑麦中具多价体的细胞频率非常相近,分别为40.7%和39.2%,明显高于远中5号/兰考小黑麦组合中的频率(33.0%)。3个组合均出现较低频率的染色体桥,分别为6%、3%、3%。在二分孢子和四分孢子中普遍观察到微核。研究结果为揭示小麦-偃麦草-黑麦属间杂种染色体遗传特征提供了依据。

In the present study,three octoploid trititrigia lines（Yuanzhong 1,Yuanzhong 3 and Yuanzhong 5） were crossed with hexaploid triticale（Lankaoxiaoheimai）,and the morphological and cytological performances of their F2 hybrids were investigated,with the purpose of laying a foundation for the development of wheat-Thinopyrum-Secale chromosome translocations.The results showed that the self-fertility rate of F2 hybrids derived from the three crosses were 28.11%,41.11% and 39.92%,respectively.Eight,twelve and twenty-nine chromosomal variations were observed among the three crosses,respectively.The numbers of chromosomes in root tip cells va-ried from 46 to 58,49 to 60 and 34 to 64,respectively.Abnormal behaviors of chromosome were observed in meiosis of pollen mother cells.The average numbers of univalent chromosome in a cell were nearly same among the three crosses（10.45,11.60 and 11.69,respectively）.The frequencies of multivalent cells in the crosses Yuanzhong 1/Lankaoxiaoheimai and Yuanzhong 3/Laokaoxiaoheimai were 40.7% and 39.2% separately,which were higher than that（33.0%） in the cross Yuanzhong 5/Lankaoxiaoheimai.Low-frequency chromosome-bridges（6%,3% and 3%,respectively） were also found in the three F2 hybrids.Dyads and tetrads with micronucleus were observed generally.The results provide a basis for revealing the genetic feature of chromosomes in wheat-Thinopyrum-Secale hybrid.