PDF(Pubmed)
Abstract：
New combinations of divergent genomes can give rise to novel genetic functions in resulting hybrid progeny. Such functions may yield opportunities for ecological divergence, contributing ultimately to reproductive isolation and evolutionary longevity of nascent hybrid lineages. In plants, the degree to which transgressive genotypes contribute to floral novelty remains a question of key interest. Here, we generated an F1 hybrid plant between the red-flowered Ruellia elegans and yellow flowered R. speciosa. RNA-seq technology was used to explore differential gene expression between the hybrid and its two parents, with emphasis on genetic elements involved in the production of floral anthocyanin pigments.
The hybrid was purple flowered and produced novel floral delphinidin pigments not manufactured by either parent. We found that nearly a fifth of all 86,475 unigenes expressed were unique to the hybrid. The majority of hybrid unigenes (80.97%) showed a pattern of complete dominance to one parent or the other although this ratio was uneven, suggesting asymmetrical influence of parental genomes on the progeny transcriptome. However, 8.87% of all transcripts within the hybrid were expressed at significantly higher or lower mean levels than observed for either parent. A total of 28 unigenes coding putatively for eight core enzymes in the anthocyanin pathway were recovered, along with three candidate MYBs involved in anthocyanin regulation.
Our results suggest that models of gene evolution that explain phenotypic novelty and hybrid establishment in plants may need to include transgressive effects. Additionally, our results lend insight into the potential for floral novelty that derives from unions of divergent genomes. These findings serve as a starting point to further investigate molecular mechanisms involved in flower color transitions in Ruellia.
The hybrid was purple flowered and produced novel floral delphinidin pigments not manufactured by either parent. We found that nearly a fifth of all 86,475 unigenes expressed were unique to the hybrid. The majority of hybrid unigenes (80.97%) showed a pattern of complete dominance to one parent or the other although this ratio was uneven, suggesting asymmetrical influence of parental genomes on the progeny transcriptome. However, 8.87% of all transcripts within the hybrid were expressed at significantly higher or lower mean levels than observed for either parent. A total of 28 unigenes coding putatively for eight core enzymes in the anthocyanin pathway were recovered, along with three candidate MYBs involved in anthocyanin regulation.
Our results suggest that models of gene evolution that explain phenotypic novelty and hybrid establishment in plants may need to include transgressive effects. Additionally, our results lend insight into the potential for floral novelty that derives from unions of divergent genomes. These findings serve as a starting point to further investigate molecular mechanisms involved in flower color transitions in Ruellia.
摘要：
不同基因组的新组合可以在产生的杂种后代中产生新的遗传功能。这些功能可能会产生生态分化的机会，最终有助于新生杂种谱系的生殖隔离和进化寿命。在植物中,越轨性基因型对花卉新颖性的贡献程度仍然是一个关键问题。这里,我们在红花的Ruelliaelegans和黄花的R.speciosa之间产生了F1杂种植物。RNA-seq技术用于探索杂种及其两个亲本之间的差异基因表达，重点是花色苷色素生产中涉及的遗传元件。
杂种是紫色的花朵，并产生了不是由任一亲本制造的新型花花飞燕草色素。我们发现，所有86,475个单基因表达的近五分之一是杂种所独有的。大多数杂种单基因（80.97％）对一个亲本或另一个亲本显示出完全优势的模式，尽管该比例不均匀，表明亲本基因组对后代转录组的不对称影响。然而,杂种中所有转录物的8.87％以明显高于或低于任一亲本观察到的平均水平表达。总共回收了28个单基因，这些单基因被假定编码花青素途径中的8个核心酶，以及三个参与花青素调节的候选MYB。
我们的结果表明，解释植物中表型新颖性和杂种建立的基因进化模型可能需要包括越权效应。此外,我们的研究结果有助于我们深入了解来自不同基因组结合的花卉新颖性的潜力.这些发现可作为进一步研究Ruellia中花颜色转变的分子机制的起点。
杂种是紫色的花朵，并产生了不是由任一亲本制造的新型花花飞燕草色素。我们发现，所有86,475个单基因表达的近五分之一是杂种所独有的。大多数杂种单基因（80.97％）对一个亲本或另一个亲本显示出完全优势的模式，尽管该比例不均匀，表明亲本基因组对后代转录组的不对称影响。然而,杂种中所有转录物的8.87％以明显高于或低于任一亲本观察到的平均水平表达。总共回收了28个单基因，这些单基因被假定编码花青素途径中的8个核心酶，以及三个参与花青素调节的候选MYB。
我们的结果表明，解释植物中表型新颖性和杂种建立的基因进化模型可能需要包括越权效应。此外,我们的研究结果有助于我们深入了解来自不同基因组结合的花卉新颖性的潜力.这些发现可作为进一步研究Ruellia中花颜色转变的分子机制的起点。
