Abstract
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 Glycine dolichocarpa (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.
Highlights
Nodulation and whole genome duplication (WGD, polyploidy) are both notable phenomena in the evolutionary history of legumes (Leguminosae)
Much progress has been made in recent years in understanding these independent phenomena; the potential interactions between the two remain poorly understood, which is true with respect to the metabolic, genetic and expression-level changes that can alter nodulation responses in polyploids
Expression in allopolyploid T2 transcriptome samples was broadly intermediate relative to its diploid progenitors; our results indicated that the allopolyploid had a reduced overall transcriptional response to rhizobia, in terms of genes regulated in response to inoculation, compared with one or both diploid progenitors, while having an enhanced symbiotic response
Summary
Nodulation and whole genome duplication (WGD, polyploidy) are both notable phenomena in the evolutionary history of legumes (Leguminosae). Much progress has been made in recent years in understanding these independent phenomena; the potential interactions between the two remain poorly understood, which is true with respect to the metabolic, genetic and expression-level changes that can alter nodulation responses in polyploids. The nitrogen-fixing root nodules formed in such symbioses are a key source of nitrogen for many legumes and account for important contributions to agricultural and natural systems [1,2]. Nodulation symbioses occur in a wide taxonomic diversity of legumes, and involve even more phylogenetically diverse bacteria (termed ‘rhizobia’) [3]. The signaling between partners involves Nod factors—lipochitooligosaccharides synthesized by rhizobia in response to Nod factor-inducing compounds (often flavonoids) from a host plant’s
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
