Shi L., Zhu T., Mogensen H. L., Keim P.
Department of Biological Sciences, Box 5640, Northern Arizona University, Flagstaff, Arizona 86011-5640.
Plant Cell. 1996 May;8(5):815-821. doi: 10.1105/tpc.8.5.815.
The two sperm cells of common origin within the pollen tube of flowering plants are each involved in a fertilization event. It has long been recognized that preferential fusion of one sperm with the egg can occur in B chromosome-containing lines of maize. If the second pollen mitosis begins with a single B chromosome, nondisjunction will result in one sperm possessing two B chromosomes and the other containing no B chromosomes. The B chromosome-containing sperm most often fertilizes the egg, whereas the sperm nucleus with no B chromosomes fuses with the polar nuclei. Despite the obvious advantages of being able to recognize and then track, separate, and analyze one sperm type from the other, it has not been possible because of the lack of sufficient detectable differences between the two types of sperms. In this study, we used a B chromosome-specific DNA sequence (pZmBs) and in situ hybridization to identify and track the B chromosome-containing sperm cell within mature pollen and pollen tubes. Our results are consistent with conclusions from previous genetic studies related to B chromosome behavior during pollen formation. Within pollen tubes, the position in which the B chromosome-containing sperm travels (leading or trailing) in relation to the sperm cell lacking B chromosomes appears to be random.
开花植物花粉管内起源相同的两个精子分别参与一次受精事件。长期以来人们已经认识到，在含有B染色体的玉米品系中，一个精子与卵细胞的优先融合会发生。如果第二次花粉有丝分裂开始时只有一条B染色体，不分离将导致一个精子拥有两条B染色体，另一个精子不含B染色体。含有B染色体的精子最常使卵细胞受精，而不含B染色体的精核与极核融合。尽管能够识别、追踪、分离并分析一种精子类型相对于另一种精子类型具有明显优势，但由于两种精子之间缺乏足够的可检测差异，一直无法做到这一点。在本研究中，我们使用B染色体特异性DNA序列（pZmBs）和原位杂交来识别并追踪成熟花粉和花粉管内含有B染色体的精子细胞。我们的结果与先前关于花粉形成过程中B染色体行为的遗传研究得出的结论一致。在花粉管内，含有B染色体的精子相对于不含B染色体的精子移动的位置（在前或在后）似乎是随机的。
