Co-Innovation Center for Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing, 210037, China.
Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, School of Life Sciences, Fudan University, Shanghai, 200438, China.
BMC Genomics. 2019 Nov 8;20(1):828. doi: 10.1186/s12864-019-6222-z.
The merging of two divergent genomes during hybridization can result in the remodeling of parental gene expression in hybrids. A molecular basis underling expression change in hybrid is regulatory divergence, which may change with the parental genetic divergence. However, there still no unanimous conclusion for this hypothesis.
Three species of Camellia with a range of genetic divergence and their F hybrids were used to study the effect of parental genetic divergence on gene expression and regulatory patterns in hybrids by RNA-sequencing and allelic expression analysis. We found that though the proportion of differentially expressed genes (DEGs) between the hybrids and their parents did not increase, a greater proportion of DEGs would be non-additively (especially transgressively) expressed in the hybrids as genomes between the parents become more divergent. In addition, the proportion of genes with significant evidence of cis-regulatory divergence increased, whereas with trans-regulatory divergence decreased with parental genetic divergence.
The discordance within hybrid would intensify as the parents become more divergent, manifesting as more DEGs would be non-additively expressed. Trans-regulatory divergence contributed more to the additively inherited genes than cis, however, its contribution to expression difference would be weakened as cis mutations accumulated over time; and this might be an important reason for that the more divergent the parents are, the greater proportion of DEGs would be non-additively expressed in hybrid.
杂交过程中两个差异基因组的融合可能导致杂种中亲本基因表达的重塑。杂种中表达变化的分子基础是调控分歧，这种分歧可能随着亲本遗传分歧而改变。然而，对于这个假设仍然没有一致的结论。
我们使用三个具有不同遗传差异的山茶花物种及其 F1 杂种，通过 RNA-seq 和等位基因表达分析，研究了亲本遗传差异对杂种基因表达和调控模式的影响。我们发现，尽管杂种与其亲本之间差异表达基因（DEGs）的比例没有增加，但随着亲本之间基因组差异的增加，更多的 DEGs 将表现出非加性（特别是超显性）表达。此外，具有显著顺式调控分歧证据的基因比例增加，而具有显著反式调控分歧证据的基因比例减少。
随着亲本的差异增加，杂种内部的不协调性会加剧，表现为更多的 DEGs 将表现出非加性表达。反式调控分歧对可加性遗传基因的贡献大于顺式，但随着顺式突变的积累，其对表达差异的贡献会减弱；这可能是亲本差异越大，杂种中更多的 DEGs 将表现出非加性表达的一个重要原因。
