高粱同源四倍体及其杂交种的细胞遗传学研究

Studies on Cytogenetics of Autotetraploid Sorghum and Its Hybrids

对同源四倍体高粱品系和杂交种的细胞学观察发现，其减数分裂的各个时期均有特异性。具体表现在，前期Ⅰ有３．９４％的ＰＭＣ中存在多个核仁，其中以双核仁形式出现的频率最高；终变期—中期Ⅰ具有不同的染色体构型，可观察到同源染色体的四种组成形式；后期Ⅰ出现大量落后染色体，其中以单价体提前分离造成的染色单体落后较为常见，单价染色体落后较少；前期Ⅱ和四分体时期可观察到核外染色体；中期Ⅱ发现有部分染色体不排列于赤道板上；后期Ⅱ仍有新的落后染色体产生。对四价体频率和后期Ⅰ带有落后染色体细胞出现频率进行的统计分析发现，品系间和不同的杂交种间存在显著的差异，说明染色体的配对能力和正常分配能力均受基因型影响。研究还发现，这两个重要的细胞学现象具有明显的负向超亲优势，杂交种的四价体频率明显降低，落后染色体明显减少。

The meiosis of autotetraploid sorghum lines and their hybrids has specific charateristics.At prophase I,there are 3.94% PMC with 2 or more nucleoli. From diakinesis to metaphase I, all of the homologous configurations can be observed. In anaphase I cells,there are numbers of chromosome lagged,and most of them are chromatids.Chromosomes out of nuclei can be seen both at prophase Ⅱ and tetrad period. Some of the chromosomes are found not to rank at equatorial plate in metaphase Ⅱ cells. New lagging chromosomes still appear at anaphase Ⅱ.The variance analysis has showed that the frequencies of qudravalent and anaphase cell with laggards are significantly different both among lines and hybrids or among all of them.In view of the above,the conclusion can be drawn that the pairing probability of homologous chromosomes is largely influenced by genotypes. It is found that hybrids had much less qudravalends and lower frequency of lagging chromosomes.