Comparative RNA-seq analysis of nickel hyperaccumulating and non-accumulating populations of Senecio coronatus (Asteraceae)

Stuart Kurt Meier, Nicolette Adams, Michael Wolf, Kevin Balkwill, A. Muthama Muasya, Christoph A Gehring, Jacqueline M. Bishop, Robert A. Ingle

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

The majority of metal hyperaccumulating plants accumulate nickel, yet the molecular basis of Ni hyperaccumulation is not well understood. We chose Senecio coronatus to investigate this phenomenon as this species displays marked variation in shoot Ni content across ultramafic outcrops in the Barberton Greenstone Belt (South Africa), thus allowing an intra-specific comparative approach to be employed. No correlation between soil and shoot Ni contents was observed, suggesting that this variation has a genetic rather than environmental basis. This was confirmed by our observation that the accumulation phenotype of plants from two hyperaccumulator and two non-accumulator populations was maintained when the plants were grown on a soil mix from these four sites for twelve months. We analysed the genetic variation among twelve serpentine populations of S. coronatus, and used RNA-Seq for de novo transcriptome assembly and analysis of gene expression in hyperaccumulator versus non-accumulator populations. Genetic analysis revealed the presence of hyperaccumulators in two well-supported evolutionary lineages, indicating that Ni hyperaccumulation may have evolved more than once in this species. RNA-Seq analysis indicated that putatative homologues of transporters associated with root iron uptake in plants are expressed at elevated levels in roots and shoots of hyperaccumulating populations of S. coronatus from both evolutionary lineages. We hypothesise that Ni hyperaccumulation in S. coronatus may have evolved through recruitment of these transporters, which play a role in the iron-deficiency response in other plant species. This article is protected by copyright. All rights reserved.
Original languageEnglish (US)
Pages (from-to)1023-1038
Number of pages16
JournalThe Plant Journal
Volume95
Issue number6
DOIs
StatePublished - Jul 17 2018

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