四倍体甜瓜花粉母细胞减数分裂的观察

Meiosis of pollen mother cells in homologous tetraploid melon

以同源四倍体甜瓜为材料,采用常规压片法研究花粉母细胞减数分裂行为。结果表明:同源四倍体甜瓜花粉母细胞减数分裂过程与二倍体类似,但有其特殊性。主要表现在:粗线期观察到有6.7%的细胞出现双核;终变期的四倍体染色体构型较复杂,有二价体、多价体、三价体和单价体;中期I和中期II有赤道板外染色体;后期I和后期II出现染色体桥和落后染色体;四分体时期出现二分体、三分体和多分体。花粉母细胞减数分裂的异常是同源四倍体甜瓜育性低的细胞学原因。

Meiotic behaviors of pollen mother cells （PMCs）in tetraploid melon were studied using regular chromosome preparation. The results showed that meiosis of the tetraploid melon was similar to that of diploid melon with some special behaviors. In pachytene ,6.7% of cells were observed with double nueleolus. Complex configurations were found in diakinesis, including bivalent, multivalent, trivalent and univalent. Some chromosomes were seen not at the equator in metaphase Ⅰ and metaphase Ⅱ cells. In anaphaseⅠ and anaphase Ⅱ, there were chromosome bridges and lagging chromosomes. Dyad, triad, tetrad and polyad appeared at tetrad stage. In conclusion, abnormal meiosis of PMCs is the cytogenetic causes for fertility reduction of tetraploid melon.