摘 要 ：利用醋酸洋红染色压片技术,以温室水培小钻‘白城杨2号’（Populus×xiaozhuanica W.Y.Hsu et Liang cv.‘Baicheng-2’）为材料,对其小孢子发生过程中染色体行为及花粉大小变异进行研究。结果表明:（1）‘白城杨2号’小孢子母细胞减数分裂过程中染色体行为存在一定比例的异常现象,包括终变期单价体、中期Ⅰ染色体提前分离、后期Ⅰ和Ⅱ落后染色体和染色体桥、末期Ⅰ和Ⅱ微核、中期Ⅱ纺锤体定位异常以及胞质分裂异常等,这些异常现象的发生与‘白城杨2号’杂种起源有密切关系。（2）‘白城杨2号’小孢子母细胞减数分裂过程中核仁数目存在动态变化,末期Ⅰ和Ⅱ的子核中最多可看到8个小核仁,可能与杨属树种的多倍体起源有关,其染色体组中可能包含8对具核仁组织者区的染色体。（3）‘白城杨2号’产生空瘪花粉率为3.67%,饱满花粉直径在21.3～52.2 μm之间,频率分布总体呈近似高斯分布,0.69%的花粉直径超过37 μm,表明其可能产生少量未减数的2n花粉。
Abstract:Chromosome behavior during microsporogenesis and variation of pollen size of Populus×xiaozhuanica W.Y.Hsu et Liang cv.‘Baicheng-2’ in greenhouse were studied by aceto-carmine squash technique.The results were as follows:(1)Some meiotic abnormalities,such as univalent in diakinesis,precocious migrated chromosomes in metaphase Ⅰ,lagging chromosomes and bridges in anaphase Ⅰ and Ⅱ,micronuclei in telophase Ⅰ and Ⅱ,abnormal orientation of spindles in metaphase Ⅱ and aberrant cytokinesis,were found with certain frequencies,which could be related with the hybrid origin of the ‘Baicheng-2’.(2)The nucleolus number changed dynamically from one to eight.In daughter nuclei of some telophase Ⅰ and Ⅱ cells,at most 8 small nucleoli were observed,which was probably related with polyploid origin of the genus Populus.The genome of the ‘Baicheng-2’ may have 8 pairs of chromosomes with nucleolus organizer regions.(3) The ‘Baicheng-2’ produced 3.67% empty and shrunken pollen grains.The diameter of plump grains ranged from 21.3 to 52.2 μm,and the frequency of pollen diameter followed a similar Gaussian distribution.However,the diameters of 0.69% pollen grains were more than 37 μm,suggesting a few of unreduced 2n pollen might be produced.