Polyploidy is an important evolutionary mechanism and is prevalent among land plants. Most polyploid species examined have multiple origins, which provide genetic diversity and may enhance the success of polyploids. In some polyploids, recurrent origins can result from reciprocal crosses between the same diploid progenitors. Although great progress has been made in understanding the genetic consequences of polyploidy, the genetic implications of reciprocal polyploidization remain poorly understood, especially in natural polyploids. Tragopogon (Asteraceae) has become an evolutionary model system for studies of recent and recurrent polyploidy. Allotetraploid T. miscellus has formed reciprocally in nature with resultant distinctive floral and inflorescence morphologies (i.e., short- vs. long-liguled forms). In this study, we performed comparative inflorescence transcriptome analyses of reciprocally formed T. miscellus and its diploid parents, T. dubius and T. pratensis. In both forms of T. miscellus, homeolog expression of ∼70% of the loci showed vertical transmission of the parental expression patterns (i.e., parental legacy), and ∼20% of the loci showed biased homeolog expression, which was unbalanced toward T. pratensis. However, 17.9% of orthologous pairs showed different homeolog expression patterns between the two forms of T. miscellus. No clear effect of cytonuclear interaction on biased expression of the maternal homeolog was found. In terms of the total expression level of the homeologs studied, 22.6% and 16.2% of the loci displayed non-additive expression in short- and long-liguled T. miscellus, respectively. Unbalanced expression level dominance toward T. pratensis was observed in both forms of T. miscellus. Significantly, genes annotated as being involved in pectin catabolic processes were highly expressed in long-liguled T. miscellus relative to the short-liguled form, and the majority of these differentially expressed genes were transgressively down-regulated in short-liguled T. miscellus. Given the known role of these genes in cell expansion, they may play a role in the differing floral and inflorescence morphologies of the two forms. In summary, the overall inflorescence transcriptome profiles are highly similar between reciprocal origins of T. miscellus. However, the dynamic homeolog-specific expression and non-additive expression patterns observed in T. miscellus emphasize the importance of reciprocal origins in promoting the genetic diversity of polyploids.

多倍体是重要的进化机制，在陆地植物中普遍存在。所检查的大多数多倍体物种具有多个起源，它们提供了遗传多样性，并可能增强多倍体的成功。在一些多倍体中，相同的二倍体祖细胞之间的相互杂交可能导致复发。尽管在理解多倍体的遗传后果方面已经取得了很大的进步，但是对相互多倍体化的遗传含义仍然知之甚少，尤其是在天然多倍体中。刺五加（菊科）已成为研究近期和复发多倍体的进化模型系统。四倍体杂种在自然界中已相互形成，并具有独特的花序和花序形态（即短和长生胶形式）。在这项研究中，我们对相互形成的花序转录组进行了比较分析杂种 和它的二倍体父母 杜比乌斯 和 鼠尾草。两种形式杂种，约70％基因座的同源基因表达显示了亲本表达模式的垂直传播（即，父母遗传），而约20％基因座显示了同源同源表达的偏向，这在 鼠尾草。然而，在两种形式的直系同源对中，有17.9％的直系同源对表现出不同的同源表达模式杂种。未发现细胞核相互作用对母体同源物的偏向表达有明显影响。就所研究的同源物的总表达水平而言，分别有22.6％和16.2％的基因座在短和长舌中显示出非加性表达。杂种， 分别。表达水平对的不平衡优势鼠尾草 在两种形式的 杂种。值得注意的是，被注释为参与果胶分解代谢过程的基因在长期接触中高度表达杂种 相对于短配体形式，这些差异表达基因中的大多数在短配体中被侵袭性下调 杂种。考虑到这些基因在细胞扩增中的已知作用，它们可能在两种形式的不同花和花序形态中起作用。总而言之，花序转录组的总体概况在两个互惠起源之间是高度相似的杂种。但是，动态同源异型表达和非加性表达模式杂种 强调互惠起源在促进多倍体遗传多样性中的重要性。