杨山牡丹×紫牡丹杂交后代“梦幻”的细胞遗传学

Cytogenetics of the"Dream"hybrid from Paeonia ostii×Paeonia delavayi

进行了杨山牡丹×紫牡丹杂交后代"梦幻"体细胞的细胞遗传学研究,结果表明该品种为混倍体.对其不同染色体数目的细胞进行核型分析,核型类别分别是3B,2B,2C,与父母本有很大的差异.用植物染色体去壁低渗制片法研究了"梦幻"大孢子母细胞减数分裂双线期-后期Ⅰ的分裂过程,结果显示:所有的细胞减数分裂行为均异常,在终变期-中期Ⅰ,分别出现了多价体、单价体、二价体提前分离、染色体胶连、赤道外染色体、染色体断裂等异常现象,这些异常导致了后期Ⅰ的不等数分离,二价体或多价体不分离,染色体胶连及出现大量的染色体断片,最终不能形成正常的雌配子体.此外,在体细胞中观察到的混倍现象在生殖细胞的减数分裂过程中也得到了进一步的证实,在终变期分别出现了5_Ⅱ+断片、4_Ⅱ+3_Ⅰ,5_Ⅱ+2_Ⅰ+断片、6_Ⅱ+3_Ⅰ+断片等染色体配对构型.

A cytogenetic study of the ＂Dream＂ hybrid from Paeonia ostii x Paeonia delavayi was conducted and the results indicated that this hybrid is of mixoploidy. Karyogram of cells which had different chromosome number were analyzed, the karyogram types are 3B, 2B and 2C, very different from its parents. For the first time, the meiosis process from diakinesis to anaphase of macrosporocyte on the ＂Dream＂ has been studied in man-made plant chromosome slides by way of enzymolysis and hypotonic. The result indicated that the meiosis of all cells are abnormal： there are some abnormal phenomena such as polyvalent, univalent, bivalent advancing separation, chromosome conglutination, chromosomes arranged outside of the equatorial plate and chromosome breakage from diakinesis to metaphase I, which bring about unequal separation, non-separation of bivalent or multivalent, chromosome conglutination and appearance of much chromosome fragment in anaphase. Finally, there is no normal megagamete. Besides, the meiosis of germ cell verifies the mixoploidy observed in the somatic cell and there are chromosome pairing configurations such as 5Ⅱ＋fragment、4Ⅱ＋3Ⅰ,5Ⅱ＋2Ⅰ＋fragment and 6Ⅱ＋3Ⅰ＋ fragment in diakinesis.