胡杨小孢子母细胞减数分裂与花粉变异研究

Studies on Meiosis of Microspore Mother Cell and Variations of Pollen Grains in Populus euphratica

利用醋酸洋红染色法研究了胡杨小孢子母细胞减数分裂过程中花芽外部形态、花药颜色变化及其与减数分裂进程的关系,染色体行为和花粉变异。结果表明,小孢子母细胞减数分裂进程与花芽外部形态以及花药颜色密切相关;减数分裂偶线期和中期Ⅰ可以看见单价体,后期Ⅰ、末期Ⅰ以及后期Ⅱ均可见落后染色体;减数分裂末期Ⅰ和末期Ⅱ核仁数目存在着动态变化,这种现象可能与杨属植物古多倍性起源有关;不同基因型间花粉粒直径的差异显著;除基因型HY17和HY31之外,其他基因型均可产生天然2n花粉,其频率在0.49%~4.37%之间变化,天然2n花粉的发生可能与后期Ⅱ纺锤体定位异常有关;低频率的连体花粉广泛存在于不同基因型的胡杨花粉中,这预示着胡杨小孢子发生过程中的胞质分裂存在异常。

Relationships between meiotic stage and shapes of flower bud and anther color,chromosome behavior during meiosis and variations of pollen grains were investigated by aceto-carmine squash technique in Populus euphratica.A high correlation between meiotic process of pollen mother cells and shape of flower bud and anther color was observed.Univalents were showed at both diplotene and metaphaseⅠ,lagging chromosomes at anaphaseⅠ,telophaseⅠ and anaphaseⅡ.The varied number of nucleoli was demonstrated at both telophaseⅠ and telophaseⅡ,suggesting that Populus maybe derive from ancient polyploid plants.However,genotypic differences in diameter of pollen grain were significant.All studied genotypes could produce natural 2n pollen except for genotype HY17 and HY31,and the frequency of 2n pollen varied from 0.49% to 4.37%,which was due to abnormal spindle orientation at metaphaseⅡ.Additionally,all the studied genotypes could produce stuck pollen grains,suggesting that abnormal cytokinesis would be happened during microsporogenesis in P.euphratica.