The cause of abortion of male gamete in Pinellia ternata was studied through the investigation of the process of meiosis, the microspore development and the chromosome number of the somatic cells of P. ternata contained 90 chromosomes, but its meiosis was abnormal. Although most of the homologous chromosomes paired at synapsis, forming bivalents, there were always also some univalents or multivalents. Leading to unbalanced segregation of the chromosomes. Abnormal structures such as laggard chromosomes, chromosome bridge and micronuclei could be observed at every phase of meiosis. All these indicated that P. ternata is a complex species with variation of chromosome constitution, and the complexity and variation, in turn, was the main cause of the abortion of the pollens of P. ternata. However, the microsporocytes could complete their meiosis process to form microspores. And the haplonucleus microspore could go through two mitosises to form trinuclei pollen grain. It is at the trinucleate phase that the abortion of the pollen grains became evielent. Less than 1% of the matured pollen grain were fertile.%从减数分裂过程，小孢子发育和染色体数目与组成三方面探讨了三叶半夏雄配子败育的原因。三叶半夏(Pinellia ternata)体细胞染色体数目2n＝90，其减数分裂异常，多数同源染色体能配对形成二价体，部分同源染色体呈单价体形式或配对成多价体。减数分裂的各时期都能观察到导致遗传物质不均衡分离的异常结构，如落后染色体，染色体桥和微核等。根据结果推测：三叶半夏是具有染色体结构变异的多倍体复合种。染色体结构变异是三叶半夏雄配子败育的主要原因。小孢子母细胞都能完成减数分裂过程，且单核小孢子能通过两次有丝分裂形成三核花粉粒。成熟花粉粒中可育花粉不足1％。三核期是雄配子败育的时期。
展开▼
