When do different C4 leaf anatomies indicate independent C4 origins? Parallel evolution of C4 leaf types in Camphorosmeae (Chenopodiaceae)

Gudrun Kadereit, Maximilian Lauterbach, Michael D. Pirie, Rami Arafeh, Helmut Freitag

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Broad-scale phylogenetic studies give first insights in numbers, relationships, and ages of C-4 lineages. They are, however, generally limited to a model that treats the evolution of the complex C-4 syndrome in different lineages as a directly comparable process. Here, we use a resolved and well-sampled phylogenetic tree of Camphorosmeae, based on three chloroplast and one nuclear marker and on leaf anatomical traits to infer a more detailed picture of C-4 leaf-type evolution in this lineage. Our ancestral character state reconstructions allowed two scenarios: (i) Sedobassia is a derived C-3/C-4 intermediate, implying two independent gains of C-4 in Bassia and Camphorosma; or (ii) Sedobassia is a plesiomorphic C-3/C-4 intermediate, representing a syndrome ancestral to the Bassia/Camphorosma/Sedobassia lineage. In Bassia, a kochioid leaf type (Bassia muricata and/or Bassia prostrata type) is ancestral. At least three independent losses of water-storage tissue occurred, resulting in parallel shifts towards an atriplicoid leaf type. These changes in leaf anatomy are adaptations to different survival strategies in steppic or semi-desert habitats with seasonal rainfall. In contrast, Camphorosma shows a fixed C-4 anatomy differing from Bassia types in its continuous Kranz layer, which indeed points to an independent origin of the full C-4 syndrome in Camphorosma, either from an independent C-3 or from a common C-3/C-4 intermediate ancestor, perhaps similar to its C-3/C-4 intermediate sister genus Sedobassia. The enlarged bundle sheath cells of Sedobassia might represent an important early step in C-4 evolution in Camphorosmeae.

Original languageEnglish
Pages (from-to)3499-3511
Number of pages13
JournalJournal of Experimental Botany
Volume65
Issue number13
DOIs
Publication statusPublished - 8 May 2014
Externally publishedYes

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