Comparative transcriptome analysis suggests convergent evolution of desiccation tolerance in Selaginella species

Gerardo Alejo-Jacuinde,Luis Herrera-Estrella,Araceli Oropeza-Aburto,June Simpson,Sandra Isabel González-Morales

doi:10.1186/s12870-020-02638-3

Gerardo Alejo-Jacuinde, Luis Herrera-Estrella + Show 3 more

Open Access

https://doi.org/10.1186/s12870-020-02638-3

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Abstract

BackgroundDesiccation tolerant Selaginella species evolved to survive extreme environmental conditions. Studies to determine the mechanisms involved in the acquisition of desiccation tolerance (DT) have focused on only a few Selaginella species. Due to the large diversity in morphology and the wide range of responses to desiccation within the genus, the understanding of the molecular basis of DT in Selaginella species is still limited.ResultsHere we present a reference transcriptome for the desiccation tolerant species S. sellowii and the desiccation sensitive species S. denticulata. The analysis also included transcriptome data for the well-studied S. lepidophylla (desiccation tolerant), in order to identify DT mechanisms that are independent of morphological adaptations. We used a comparative approach to discriminate between DT responses and the common water loss response in Selaginella species. Predicted proteomes show strong homology, but most of the desiccation responsive genes differ between species. Despite such differences, functional analysis revealed that tolerant species with different morphologies employ similar mechanisms to survive desiccation. Significant functions involved in DT and shared by both tolerant species included induction of antioxidant systems, amino acid and secondary metabolism, whereas species-specific responses included cell wall modification and carbohydrate metabolism.ConclusionsReference transcriptomes generated in this work represent a valuable resource to study Selaginella biology and plant evolution in relation to DT. Our results provide evidence of convergent evolution of S. sellowii and S. lepidophylla due to the different gene sets that underwent selection to acquire DT

Highlights

Desiccation tolerant Selaginella species evolved to survive extreme environmental conditions
Characterization of desiccation tolerance (DT) in Selaginella sellowii To identify shared or specific functions relevant to the acquisition of DT in Selaginella species with different morphologies, and to discriminate between the shared and conserved responses to water loss from the response to desiccation, we compared RNA-Seq data from two Selaginella species with similar morphologies that differ in DT properties with a tolerant species with a distinct morphology
S. sellowii has previously been reported as desiccation tolerant, we decided to confirm this evaluation with our samples

Summary

Introduction

Desiccation tolerant Selaginella species evolved to survive extreme environmental conditions. The origin of the Selaginella genus has been estimated at around 383 million years ago [1] This group of plants represents one of the oldest lineages of vascular plants (Fig. 1) and includes over 700 species [2, 7, 8]. The. Selaginella genus occupies a broad diversity of habitats, mainly in humid environments, some species are adapted to extremely arid conditions [1, 3]. Selaginella genus occupies a broad diversity of habitats, mainly in humid environments, some species are adapted to extremely arid conditions [1, 3] Some of these latter species have evolved desiccation tolerance (DT), a particular trait that allows them to withstand very long periods in the desiccated state.

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