Dataset Information

Independent evolution of ancestral and novel defenses in a genus of toxic plants (Erysimum, Brassicaceae).

ABSTRACT: Phytochemical diversity is thought to result from coevolutionary cycles as specialization in herbivores imposes diversifying selection on plant chemical defenses. Plants in the speciose genus Erysimum (Brassicaceae) produce both ancestral glucosinolates and evolutionarily novel cardenolides as defenses. Here we test macroevolutionary hypotheses on co-expression, co-regulation, and diversification of these potentially redundant defenses across this genus. We sequenced and assembled the genome of E. cheiranthoides and foliar transcriptomes of 47 additional Erysimum species to construct a phylogeny from 9868 orthologous genes, revealing several geographic clades but also high levels of gene discordance. Concentrations, inducibility, and diversity of the two defenses varied independently among species, with no evidence for trade-offs. Closely related, geographically co-occurring species shared similar cardenolide traits, but not glucosinolate traits, likely as a result of specific selective pressures acting on each defense. Ancestral and novel chemical defenses in Erysimum thus appear to provide complementary rather than redundant functions.

SUBMITTER: Zust T

PROVIDER: S-EPMC7180059 | biostudies-literature | 2020 Apr

REPOSITORIES: biostudies-literature

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Publications

Independent evolution of ancestral and novel defenses in a genus of toxic plants (<i>Erysimum</i>, Brassicaceae).

Züst Tobias T Strickler Susan R SR Powell Adrian F AF Mabry Makenzie E ME An Hong H Mirzaei Mahdieh M York Thomas T Holland Cynthia K CK Kumar Pavan P Erb Matthias M Petschenka Georg G Gómez José-María JM Perfectti Francisco F Müller Caroline C Pires J Chris JC Mueller Lukas A LA Jander Georg G

eLife 20200407

Phytochemical diversity is thought to result from coevolutionary cycles as specialization in herbivores imposes diversifying selection on plant chemical defenses. Plants in the speciose genus <i>Erysimum</i> (Brassicaceae) produce both ancestral glucosinolates and evolutionarily novel cardenolides as defenses. Here we test macroevolutionary hypotheses on co-expression, co-regulation, and diversification of these potentially redundant defenses across this genus. We sequenced and assembled the gen ...[more]

PMID: 32252891

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Project description:Background and aimsHybridization is a common and important force in plant evolution. One of its outcomes is introgression - the transfer of small genomic regions from one taxon to another by hybridization and repeated backcrossing. This process is believed to be common in glacial refugia, where range expansions and contractions can lead to cycles of sympatry and isolation, creating conditions for extensive hybridization and introgression. Polyploidization is another genome-wide process with a major influence on plant evolution. Both hybridization and polyploidization can have complex effects on plant evolution. However, these effects are often difficult to understand in recently evolved species complexes.MethodsWe combined flow cytometry, analyses of transcriptomic sequences and pollen tube growth assays to investigate the consequences of polyploidization, hybridization and introgression on the recent evolution of several Erysimum (Brassicaceae) species from the South of the Iberian Peninsula, a well-known glacial refugium. This species complex differentiated in the last 2 million years, and its evolution has been hypothesized to be determined mainly by polyploidization, interspecific hybridization and introgression.Key resultsOur results support a scenario of widespread hybridization involving both extant and 'ghost' taxa. Several taxa studied here, most notably those with purple corollas, are polyploids, probably of allopolyploid origin. Moreover, hybridization in this group might be an ongoing phenomenon, as pre-zygotic barriers appeared weak in many cases.ConclusionsThe evolution of Erysimum spp. has been determined by hybridization to a large extent. Species with purple (polyploids) and yellow flowers (mostly diploid) exhibit a strong signature of introgression in their genomes, indicating that hybridization occurred regardless of colour and across ploidy levels. Although the adaptive value of such genomic exchanges remains unclear, our results demonstrate the significance of hybridization for plant diversification, which should be taken into account when studying plant evolution.

Dataset Information

Independent evolution of ancestral and novel defenses in a genus of toxic plants (Erysimum, Brassicaceae).

Publications

Independent evolution of ancestral and novel defenses in a genus of toxic plants (<i>Erysimum</i>, Brassicaceae).

Similar Datasets

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