Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, 06466 Seeland, OT Gatersleben, Germany.
KWS SAAT SE & Co. KGaA, 37574, Einbeck, Germany.
Nat Commun. 2020 Jun 2;11(1):2764. doi: 10.1038/s41467-020-16594-x.
Not necessarily all cells of an organism contain the same genome. Some eukaryotes exhibit dramatic differences between cells of different organs, resulting from programmed elimination of chromosomes or their fragments. Here, we present a detailed analysis of programmed B chromosome elimination in plants. Using goatgrass Aegilops speltoides as a model, we demonstrate that the elimination of B chromosomes is a strictly controlled and highly efficient root-specific process. At the onset of embryo differentiation B chromosomes undergo elimination in proto-root cells. Independent of centromere activity, B chromosomes demonstrate nondisjunction of chromatids and lagging in anaphase, leading to micronucleation. Chromatin structure and DNA replication differ between micronuclei and primary nuclei and degradation of micronucleated DNA is the final step of B chromosome elimination. This process might allow root tissues to survive the detrimental expression, or overexpression of B chromosome-located root-specific genes with paralogs located on standard chromosomes.
并非生物的所有细胞都含有相同的基因组。一些真核生物在不同器官的细胞之间表现出显著差异，这是由于染色体或其片段的程序性消除所致。在这里，我们对植物中程序性 B 染色体消除进行了详细分析。我们以山羊草 Aegilops speltoides 为模型，证明了 B 染色体的消除是一个严格控制的、高度有效的根特异性过程。在胚胎分化开始时，B 染色体在原根细胞中被消除。与着丝粒活性无关，B 染色体表现出染色单体的不分离和后期的滞后，导致微核形成。微核和原始核之间的染色质结构和 DNA 复制不同，微核化 DNA 的降解是 B 染色体消除的最后一步。这个过程可能允许根组织在 B 染色体上的根特异性基因的有害表达或过表达，而这些基因的同源基因位于标准染色体上。
