e-journal

Gene and genome duplications and the origin of C4photosynthesis:Birth of a trait in the Cleomaceae

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tC4photosynthesis is a trait that has evolved in 66 independent plant lineages and increases the efficiencyof carbon fixation. The shift from C3to C4photosynthesis requires substantial changes to genes andgene functions effecting phenotypic, physiological and enzymatic changes. We investigate the role ofancient whole genome duplications (WGD) as a source of new genes in the development of this trait andcompare expression between paralog copies. We compare Gynandropsis gynandra, the closest relativeof Arabidopsis that uses C4photosynthesis, with its C3relative Tarenaya hassleriana that underwenta WGD named Th-. We establish through comparison of paralog synonymous substitution rate thatboth species share this paleohexaploidy. Homologous clusters of photosynthetic gene families show thatgene copy numbers are similar to what would be expected given their duplication history and that nosignificant difference between the C3and C4species exists in terms of gene copy number. This is furtherconfirmed by syntenic analysis of T. hassleriana, Arabidopsis thaliana and Aethionema arabicum, wheresyntenic region copy number ratios lie close to what could be theoretically expected. Expression levels ofC4photosynthesis orthologs show that regulation of transcript abundance in T. hassleriana is much lessstrictly controlled than in G. gynandra, where orthologs have extremely similar expression patterns indifferent organs, seedlings and seeds. We conclude that the Th- and older paleopolyploidy events havehad a significant influence on the specific genetic makeup of Cleomaceae versus Brassicaceae. Becausethe copy number of various essential genes involved in C4photosynthesis is not significantly influencedby polyploidy combined with the fact that transcript abundance in G. gynandra is more strictly controlled,we also conclude that recruitment of existing genes through regulatory changes is more likely to haveplayed a role in the shift to C4than the neofunctionalization of duplicated genes.DATA: The data deposited at NCBI represents raw RNA reads for each data series mentioned: 5 leafstages, root, stem, stamen, petal, carpel, sepal, 3 seedling stages and 3 seed stages of Tarenaya hasslerianaand Gynandropsis gynandra. The assembled reads were used for all analyses of this paper where RNAwas used.

Keywords:
Plant genome evolution Synteny Cleomaceae Brassicaceae Bioinformatics Whole genome duplicationPaleopolyploidyC4photosynthesis

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Informasi Detail

Judul Seri

Current Plant Biology

No. Panggil

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Penerbit

: Elsevier., 2014

Deskripsi Fisik

Current Plant Biology 1 (2014) 2–9

Bahasa

English

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Klasifikasi

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Tipe Isi

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Tipe Media

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Tipe Pembawa

-

Edisi

-

Subjek

KIMIA

Info Detail Spesifik

-

Pernyataan Tanggungjawab

Wati/Agus

Versi lain/terkait

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