Powell Adrian F, Doyle Jeff J
Section of Plant Biology, School of Integrated Plant Sciences, Cornell University, Ithaca, NY 14853, USA.
Boyce Thompson Institute, Ithaca, NY 14853, USA.
Genes (Basel). 2017 Nov 30;8(12):357. doi: 10.3390/genes8120357.
Root nodule symbioses (nodulation) and whole genome duplication (WGD, polyploidy) are both important phenomena in the legume family (Leguminosae). Recently, it has been proposed that polyploidy may have played a critical role in the origin or refinement of nodulation. However, while nodulation and polyploidy have been studied independently, there have been no direct studies of mechanisms affecting the interactions between these phenomena in symbiotic, nodule-forming species. Here, we examined the transcriptome-level responses to inoculation in the young allopolyploid (T2) and its diploid progenitor species to identify underlying processes leading to the enhanced nodulation responses previously identified in T2. We assessed the differential expression of genes and, using weighted gene co-expression network analysis (WGCNA), identified modules associated with nodulation and compared their expression between species. These transcriptomic analyses revealed patterns of non-additive expression in T2, with evidence of transcriptional responses to inoculation that were distinct from one or both progenitors. These differential responses elucidate mechanisms underlying the nodulation-related differences observed between T2 and the diploid progenitors. Our results indicate that T2 has reduced stress-related transcription, coupled with enhanced transcription of modules and genes implicated in hormonal signaling, both of which are important for nodulation.
根瘤共生（结瘤）和全基因组复制（WGD，多倍体化）都是豆科植物中的重要现象。最近，有人提出多倍体化可能在结瘤的起源或完善过程中发挥了关键作用。然而，虽然结瘤和多倍体化已被分别研究，但尚未有对共生结瘤物种中影响这些现象之间相互作用机制的直接研究。在这里，我们研究了年轻的异源多倍体（T2）及其二倍体祖先物种对接种的转录组水平反应，以确定导致先前在T2中发现的结瘤反应增强的潜在过程。我们评估了基因的差异表达，并使用加权基因共表达网络分析（WGCNA）确定了与结瘤相关的模块，并比较了它们在物种间的表达。这些转录组分析揭示了T2中的非加性表达模式，有证据表明对接种的转录反应与一个或两个祖先不同。这些差异反应阐明了T2与二倍体祖先之间观察到的结瘤相关差异的潜在机制。我们的结果表明，T2减少了与应激相关的转录，同时增强了与激素信号传导相关的模块和基因的转录，这两者对结瘤都很重要。
