Differential gene expression reveals mechanisms related to habitat divergence between hybridizing orchids from the Neotr
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RESEARCH ARTICLE
Open Access
Differential gene expression reveals mechanisms related to habitat divergence between hybridizing orchids from the Neotropical coastal plains Bárbara Simões Santos Leal1* , Marcelo Mendes Brandão2, Clarisse Palma-Silva1 and Fabio Pinheiro1
Abstract Background: Closely related hybridizing species are ideal systems for identifying genomic regions underlying adaptive divergence. Although gene expression plays a central role in determining ecologically-based phenotypic differences, few studies have inferred the role of gene expression for adaptive divergence in Neotropical systems. In this study, we conduct genome-wide expression analysis alongside soil elemental analysis in sympatric and allopatric populations of Epidendrum fulgens and E. puniceoluteum (Orchidaceae), which occur in contrasting adjacent habitats in the Neotropical coastal plains. Results: These species were highly differentiated by their gene expression profiles, as determined by 18–21% of transcripts. Gene ontology (GO) terms associated with reproductive processes were enriched according to comparisons between species in both allopatric and sympatric populations. Species showed differential expression in genes linked to salt and waterlogging tolerance according to comparisons between species in sympatry, and biological processes related to environmental stimulus appeared as representative among those transcripts associated with edaphic characteristics in each sympatric zone. Hybrids, in their turn, were well differentiated from E. fulgens, but exhibited a similar gene expression profile to flooding-tolerant E. puniceolutem. When compared with parental species, hybrids showed no transcripts with additive pattern of expression and increased expression for almost all transgressive transcripts. Conclusions: This study sheds light on general mechanisms promoting ecological differentiation and assortative mating, and suggests candidate genes, such as those encoding catalase and calcium-dependent protein kinase, underling adaptation to harsh edaphic conditions in the Neotropical coastal plains. Moreover, it demonstrates that differential gene expression plays a central role in determining ecologically-based phenotypic differences among co-occurring species and their hybrids. Keywords: Ecological genomics, Edaphic adaptation, Neotropical speciation, Orchids, Restingas, Transcription profile
* Correspondence: [email protected] 1 Departamento de Biologia Vegetal, Universidade Estadual de Campinas, Campinas, SP 13083-862, Brazil Full list of author information is available at the end of the article © The Author(s). 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article
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