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Ι染色体的构型复杂,中期Ι和中期Ⅱ有赤道板外染色体;后期Ι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。
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 meio- sis 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 ＋sm ＋1T）, which indi- cates 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,chromo- some bridge and fragment. During anaphase Ⅱ and telophase Ⅱ chromosome segregation was not synchro- nous 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 cytoge- netic reason of fertility reduction of T. antungense pollen.
出处
《西北植物学报》
CAS
CSCD
北大核心
2012年第12期2419-2425,共7页
Acta Botanica Boreali-Occidentalia Sinica
基金
国家农业部野生植物资源保护项目(农计发[2010]29号)
关键词
斑叶蒲公英
染色体
核型
减数分裂
四倍体
Taraxacum antungense
chromosome
karyotype
meiosis
allotetraploid
