Diversification of defensins and NLRs in Arabidopsis species by different evolutionary mechanisms

URN to cite this document: urn:nbn:de:bvb:355-epub-366434

Mondragón-Palomino, Mariana , Stam, Remco , John-Arputharaj, Ajay and Dresselhaus, Thomas (2017) Diversification of defensins and NLRs in Arabidopsis species by different evolutionary mechanisms. BMC Evolutionary Biology 17 (1), pp. 1-23.

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Date of publication of this fulltext: 29 Jan 2018 18:04

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Other URL: http://doi.org/10.1186/s12862-017-1099-4, https://bmcevolbiol.biomedcentral.com/articles/10.1186/s12862-017-1099-4

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Abstract

Abstract

Background: Genes encoding proteins underlying host-pathogen co-evolution and which are selected for new resistance specificities frequently are under positive selection, a process that maintains diversity. Here, we tested the contribution of natural selection, recombination and transcriptional divergence to the evolutionary diversification of the plant defensins superfamily in three Arabidopsis species. The intracellular NOD-like receptor (NLR) family was used for comparison because positive selection has been well documented in its members. Similar to defensins, NLRs are encoded by a large and polymorphic gene family and many of their members are involved in the immune response. Results: Gene trees of Arabidopsis defensins (DEFLs) show a high prevalence of clades containing orthologs. This indicates that their diversity dates back to a common ancestor and species-specific duplications did not significantly contribute to gene family expansion. DEFLs are characterized by a pervasive pattern of neutral evolution with infrequent positive and negative selection as well as recombination. In comparison, most NLR alignment groups are characterized by frequent occurrence of positive selection and recombination in their leucine-rich repeat (LRR) domain as well negative selection in their nucleotide-binding (NB-ARC) domain. While major NLR subgroups are expressed in pistils and leaves both in presence or absence of pathogen infection, the members of DEFL alignment groups are predominantly transcribed in pistils. Furthermore, conserved groups of NLRs and DEFLs are differentially expressed in response to Fusarium graminearum regardless of whether these genes are under positive selection or not. Conclusions: The present analyses of NLRs expands previous studies in Arabidopsis thaliana and highlights contrasting patterns of purifying and diversifying selection affecting different gene regions. DEFL genes show a different evolutionary trend, with fewer recombination events and significantly fewer instances of natural selection. Their heterogeneous expression pattern suggests that transcriptional divergence probably made the major contribution to functional diversification. In comparison to smaller families encoding pathogenesis-related (PR) proteins under positive selection, DEFLs are involved in a wide variety of processes that altogether might pose structural and functional trade-offs to their family-wide pattern of evolution.

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Item type:

Article

Date:

15 December 2017

Institutions:

Biology, Preclinical Medicine > Institut für Pflanzenwissenschaften > Lehrstuhl für Zellbiologie und Pflanzenphysiologie

Projects:

Open Access Publizieren (DFG)

Identification Number:

Value	Type
10.1186/s12862-017-1099-4	DOI

Keywords:

MULTIPLE SEQUENCE ALIGNMENT; POSITIVELY SELECTED SITES; RESISTANCE GENES; SELF-INCOMPATIBILITY; MAXIMUM-LIKELIHOOD; INHIBITOR PROTEIN; ENCODING GENES; PLANT DEFENSE; SELECTION; THALIANA; NLR; NBS-LRR; Cysteine-rich peptide; Defensin; Natural selection; Gene recombination; Molecular evolution; Arabidopsis; Fusarium; RNA-seq

Dewey Decimal Classification:

500 Science > 580 Botanical sciences

Status:

Published

Refereed:

Yes, this version has been refereed

Created at the University of Regensburg:

Yes

Item ID:

36643

Owner only: item control page

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