Abstract B-chromosomes show a non-random distribution in different taxa of gymnosperms. They are generally smaller and show similar centromeric position as the normal complement and are heterochromatic in nature and may show DAPI or CMA banding. They are generally devoid of any gene content, do not pair at meiosis and show accumulation through female line. They show incremental effect on genome size and some adaptive value in particular ecological conditions.

中文翻译：

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裸子植物中的 B 染色体

摘要 B染色体在裸子植物的不同分类群中呈非随机分布。它们通常较小，显示与正常补体相似的着丝粒位置，本质上是异色的，可能显示 DAPI 或 CMA 带。它们通常不含任何基因内容，在减数分裂时不配对并通过母系显示积累。它们在特定生态条件下对基因组大小和一些适应性价值显示出增量影响。