---

作 者 ：张 建，陈倩倩，赵 鑫，宁 伟*

期 刊 ：西北植物学报 2012年 12期 页码：2419~2425

关键词：斑叶蒲公英；染色体；核型；减数分裂；四倍体；

Keywords:Taraxacum antungense, chromosome, karyotype, meiosis, allotetraploid,

摘 要 ：采用根尖压片法确定斑叶蒲公英的染色体数目，通过分析斑叶蒲公英核型及花粉母细胞减数分裂过程，以确定其倍性水平。结果表明：（1）斑叶蒲公英根尖细胞染色体数目为32条，核型公式为2n=3x+x′=32=（18m+6sm）+（3m+4sm+1T），属于2A型。（2）斑叶蒲公英花粉母细胞减数分裂为同时型胞质分裂，四分体的排列方式以正四面体型居多，十字交叉型偏少，偶见左右对称型。（3）前期Ⅰ染色体的构型复杂，中期Ⅰ和中期Ⅱ有赤道板外染色体;后期Ⅰ和后期Ⅱ出现落后染色体、染色体桥及断片;后期Ⅱ和末期Ⅱ还出现染色体分离不同步及不均等分裂的现象；四分体时期出现二分体、三分体、含微核的异常四分体及多分体等异常现象。（4）对其花粉进行离体萌发试验，花粉萌发率只有26.3%，说明斑叶蒲公英是异源四倍体，32条染色体不均等的减数分裂异常，造成花粉活性较低。

Abstract:The number of chromosomes in Taraxacum antungense was calculated by a root tip squashing method.The ploidity was analyzed by karyotyping and chromosome behavior observation during the meiosis process of pollen mother cells.Results showed that:(1)The number of chromosomes in T.antungense was 32.Its karyotype was formulated as 2n=3x+x′=32=（18m+6sm）+(3m+4sm+1T),which indicates a Stebbins’ 2A type.(2)The meiosis in T.antungense undergoes simultaneous cytokinesis.(3)Some of the chromosomes were found not to rank at metaphase plate in metaphase Ⅰ and metaphase Ⅱ cells.In anaphase Ⅰ and anaphase Ⅱ cells,observed some abnormal events including lagged chromosomes,chromosome bridge and fragment.During anaphase Ⅱ and telophase Ⅱ chromosome segregation was not synchronous and equal.At tetrad stage,dyad,triad,tetrad with micronucleus and polyad appeared.(4)The pollen germination rate in vitro was only 26.3%,which indicated that abnormal meiosis of PMCs was the cytogenetic reason of fertility reduction of T.antungense pollen.

---