Rosselló Josep A, Maravilla Alexis J, Rosato Marcela
Jardín Botánico, Instituto Cavanilles de Biodiversidad y Biología Evolutiva, Universitat de València, Valencia, Spain.
Front Plant Sci. 2022 Feb 24;13:788911. doi: 10.3389/fpls.2022.788911. eCollection 2022.
The ubiquitous presence of rRNA genes in nuclear, plastid, and mitochondrial genomes has provided an opportunity to use genomic markers to infer patterns of molecular and organismic evolution as well as to assess systematic issues throughout the tree of life. The number, size, location, and activity of the 35S rDNA cistrons in plant karyotypes have been used as conventional cytogenetic landmarks. Their scrutiny has been useful to infer patterns of chromosomal evolution and the data have been used as a proxy for assessing species discrimination, population differentiation and evolutionary relationships. The correct interpretation of rDNA markers in plant taxonomy and evolution is not free of drawbacks given the complexities derived from the lability of the genetic architecture, the diverse patterns of molecular change, and the fate and evolutionary dynamics of the rDNA units in hybrids and polyploid species. In addition, the terminology used by independent authors is somewhat vague, which often complicates comparisons. To date, no efforts have been reported addressing the potential problems and limitations involved in generating, utilizing, and interpreting the data from the 35S rDNA in cytogenetics. This review discusses the main technical and conceptual limitations of these rDNA markers obtained by cytological and karyological experimental work, in order to clarify biological and evolutionary inferences postulated in a systematic and phylogenetic context. Also, we provide clarification for some ambiguity and misconceptions in terminology usually found in published work that may help to improve the usage of the 35S ribosomal world in plant evolution.
核糖体RNA（rRNA）基因广泛存在于核基因组、质体基因组和线粒体基因组中，这为利用基因组标记来推断分子和生物进化模式以及评估整个生命树中的系统发育问题提供了契机。植物核型中35S核糖体DNA（rDNA）顺反子的数量、大小、位置和活性已被用作传统的细胞遗传学标记。对它们的详细研究有助于推断染色体进化模式，这些数据也被用作评估物种鉴别、种群分化和进化关系的替代指标。鉴于遗传结构的不稳定性、分子变化的多样模式以及杂交种和多倍体物种中rDNA单元的命运和进化动态所带来的复杂性，在植物分类学和进化中对rDNA标记的正确解读并非没有缺陷。此外，不同作者使用的术语有些模糊，这常常使比较变得复杂。迄今为止，尚未有报道致力于解决细胞遗传学中35S rDNA数据的生成、利用和解读所涉及的潜在问题和局限性。本综述讨论了通过细胞学和核型学实验工作获得的这些rDNA标记的主要技术和概念局限性，以便阐明在系统发育背景下所假定的生物学和进化推断。此外，我们还对已发表作品中常见的一些术语模糊性和误解进行了澄清，这可能有助于改进35S核糖体领域在植物进化中的应用。
