Mahelka Václav, Kopecký David, Majka Joanna, Krak Karol
Czech Academy of Sciences, Institute of Botany, Průhonice, Czechia.
Institute of Experimental Botany of the Czech Academy of Sciences, Centre of Plant Structural and Functional Genomics, Olomouc, Czechia.
Front Plant Sci. 2023 Sep 18;14:1276252. doi: 10.3389/fpls.2023.1276252. eCollection 2023.
Genome or genomic dominance (GD) is a phenomenon observed in hybrids when one parental genome becomes dominant over the other. It is manifested by the replacement of chromatin of the submissive genome by that of the dominant genome and by biased gene expression. Nucleolar dominance (ND) - the functional expression of only one parental set of ribosomal genes in hybrids - is another example of an intragenomic competitive process which, however, concerns ribosomal DNA only. Although GD and ND are relatively well understood, the nature and extent of their potential interdependence is mostly unknown. Here, we ask whether hybrids showing GD also exhibit ND and, if so, whether the dominant genome is the same. To test this, we used hybrids between and grasses (Festulolium), and between two species in which GD has been observed (with as the dominant genome in Festulolium and in interspecific hybrids). Using amplicon sequencing of ITS1 and ITS2 of the 45S ribosomal DNA (rDNA) cluster and molecular cytogenetics, we studied the organization and expression of rDNA in leaf tissue in five hybrid combinations, four generations and 31 genotypes [ × (F, F, F, BC), × (F), × (F), × (F), (F)]. We have found that instant ND occurs in Festulolium, where expression of -type rDNA reached nearly 100% in all F hybrids and was maintained through subsequent generations. Therefore, ND and GD in Festulolium are manifested by the same dominant genome (). We also confirmed the concordance between GD and ND in an interspecific cross between two species.
基因组或基因组显性（GD）是在杂种中观察到的一种现象，即一个亲本基因组相对于另一个亲本基因组占主导地位。它表现为顺从基因组的染色质被主导基因组的染色质所取代以及基因表达的偏向性。核仁显性（ND）——杂种中仅一组亲本核糖体基因的功能性表达——是基因组内竞争过程的另一个例子，然而，它仅涉及核糖体DNA。尽管GD和ND相对来说得到了较好的理解，但其潜在相互依存关系的性质和程度大多未知。在这里，我们探究表现出GD的杂种是否也表现出ND，如果是，占主导地位的基因组是否相同。为了验证这一点，我们使用了羊茅属植物（Festulolium）中两个物种之间的杂种，以及已观察到GD的两个黑麦草属物种之间的杂种（在羊茅属杂种中 为占主导地位的基因组，在种间黑麦草属杂种中 为占主导地位的基因组）。通过对45S核糖体DNA（rDNA）簇的ITS1和ITS2进行扩增子测序以及分子细胞遗传学方法，我们研究了五个杂种组合、四代以及31个基因型[ × （F1、F2、F3、BC）， × （F1）， × （F1）， × （F1）， （F1）]叶片组织中rDNA的组织和表达情况。我们发现，在羊茅属植物中会立即出现核仁显性，其中所有F1杂种中 - 型rDNA的表达几乎达到100%，并在随后的世代中得以维持。因此，羊茅属植物中的核仁显性和基因组显性由相同的占主导地位的基因组（ ）表现出来。我们还证实了两个黑麦草属物种种间杂交中基因组显性和核仁显性之间的一致性。
