Cytological characteristics of numerically unreduced pollen production in Populus tomentosa Carr.
Cytological characteristics of numerically unreduced pollen production in Populus tomentosa Carr.
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DOI：
10.1007/s10681-009-0051-0
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发表时间：
2010-05
期刊：
影响因子：
1.9
通讯作者：
Zheng-hai Zhang;X. Kang
中科院分区：
文献类型：
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作者：
Zheng-hai Zhang;X. Kang
毛白杨的天然三倍体 (2n= 3x= 57) 可能是通过正常雌配子和数量未减少的 (2n) 雄配子结合进行有性多倍化的结果。 In our microscopic study of microspore mother cells (MMCs) of diploidP. tomentosa(2n=2x=38)，我们观察到第一次减数分裂是正常的，但第二次分裂的特点是频繁出现纺锤体方向异常（平行、三极和融合纺锤体）和过早胞质分裂。平行、融合纺锤体和过早胞质分裂被认为是主导二分体形成，而三极纺锤体似乎主导四分体阶段的三联体形成。平行纺锤体的出现频率高于其他纺锤体形式，但平行纺锤体与成对纺锤体之间没有显着相关性。减数分裂II的间接免疫荧光检查显示，在具有平行纺锤体的MMC中形成了四个四方排列的核，并且这四个核之间存在放射状微管系统（RMS），从而形成四方四分体。然而，在一些MMC中，平行纺锤体导致一个或两个非姐妹染色体组的聚集，导致来自两个子核的RMS的掺入。因此，合并的 RMS 建立了三个或两个核细胞质结构域来控制分裂平面，从而形成三联体或二联体。这些结果为平行纺锤体导致花粉形成数量未减少的机制以及此类花粉在P.多倍体育种中的选择和利用提供了新的见解。绒毛。
Natural triploids ofPopulus tomentosa(2n= 3x= 57) are presumably the result of sexual polyploidization through the union of normalnfemale gametes and numerically unreduced (2n) male gametes. In our microscopic study of microspore mother cells (MMCs) of diploidP. tomentosa(2n= 2x= 38), we observed that the first meiotic division was normal but that the second division was characterized by frequent abnormal spindle orientation (parallel, tripolar, and fused spindles) and premature cytokinesis. The parallel, fused spindles and premature cytokinesis were considered to be leading dyad formation, and tripolar spindles seemed to be leading triad formation at the tetrad stage. There was a higher frequency of parallel spindles than other spindle forms, but there were no significant correlations between parallel spindles and dyads. An indirect immunofluorescence examination of meiosis II revealed that four tetragonally arranged nuclei were formed in MMCs with parallel spindles and that there were radial microtubules systems (RMSs) among these four nuclei, leading to the tetragonal tetrad. In some MMCs, however, the parallel spindles led to the gathering of one or two non-sister groups of chromosomes, causing an incorporation of RMSs from two daughter nuclei. Thus, the incorporated RMSs established three or two nuclear cytoplasmic domains for the control of division plane, resulting in either triad or dyad formation. These results provide new insights on the mechanism of parallel spindles leading to numerically unreduced pollen formation and on the selection and utilization of this type of pollen in polyploid breeding ofP. tomentosa.