Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Seeland, Germany.
Institute of Experimental Botany of the Czech Academy of Sciences, Centre of Plant Structural and Functional Genomics, Olomouc, Czech Republic.
Nat Commun. 2024 Nov 8;15(1):9686. doi: 10.1038/s41467-024-53799-w.
The genomes of many plants, animals, and fungi frequently comprise dispensable B chromosomes that rely upon various chromosomal drive mechanisms to counteract the tendency of non-essential genetic elements to be purged over time. The B chromosome of rye - a model system for nearly a century - undergoes targeted nondisjunction during first pollen mitosis, favouring segregation into the generative nucleus, thus increasing their numbers over generations. However, the genetic mechanisms underlying this process are poorly understood. Here, using a newly-assembled, ~430 Mb-long rye B chromosome pseudomolecule, we identify five candidate genes whose role as trans-acting moderators of the chromosomal drive is supported by karyotyping, chromosome drive analysis and comparative RNA-seq. Among them, we identify DCR28, coding a microtubule-associated protein related to cell division, and detect this gene also in the B chromosome of Aegilops speltoides. The DCR28 gene family is neo-functionalised and serially-duplicated with 15 B chromosome-located copies that are uniquely highly expressed in the first pollen mitosis of rye.
许多植物、动物和真菌的基因组经常包含可丢弃的 B 染色体，这些染色体依赖于各种染色体驱动机制来对抗非必需遗传元素随时间被清除的趋势。黑麦的 B 染色体——近一个世纪的模式系统——在第一次花粉有丝分裂时经历靶向不分离，有利于分配到生殖核中，从而在几代中增加其数量。然而，这一过程的遗传机制还知之甚少。在这里，我们使用新组装的、约 4.30Mb 长的黑麦 B 染色体假染色体，鉴定了五个候选基因，其作为染色体驱动的反式作用调节剂的作用得到了核型分析、染色体驱动分析和比较 RNA-seq 的支持。其中，我们鉴定了 DCR28，它编码与细胞分裂相关的微管相关蛋白，并在 Aegilops speltoides 的 B 染色体中也检测到了该基因。DCR28 基因家族是新功能化的，并且串联复制了 15 个 B 染色体定位的拷贝，这些拷贝在黑麦的第一次花粉有丝分裂中独特地高度表达。
