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J Exp Bot. 2018 Nov 26;69(22):5355-5371. doi: 10.1093/jxb/ery320.

A BAHD neofunctionalization promotes tetrahydroxycinnamoyl spermine accumulation in the pollen coat of the Asteraceae family.

Author information

1
EA 7394, USC INRA 1411, Institut Charles Viollette (ICV), Agro-food and Biotechnology Research Institute, Université de Lille, INRA, ISA, Univ. Artois, Univ. Littoral Côte d'Opale, Cité Scientifique, Villeneuve d'Ascq, France.
2
Institute for Plant Biochemistry and Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich Heine University, Universitätsstrasse, Düsseldorf, Germany.
3
Biomolécules et Biotechnologies Végétales, EA, Université de Tours, Tours, France.
4
Biologie des Plantes & Innovation (EA 3900 BIOPI), Université de Picardie Jules Verne, Amiens Cedex, France.
5
Plateforme Analytique (PFA), Université de Picardie Jules Verne, Amiens Cedex, France.

Abstract

In eudicotyledons, accumulation of trihydroxycinnamoyl spermidine that is restricted to the pollen wall constitutes an evolutionary conserved trait. However, the role of this compound, which is synthetized by the BAHD enzyme spermidine hydroxycinnamoyl transferase (SHT), is still a matter of debate. Here, we show that this particular phenolamide is replaced by tetrahydroxycinnamoyl spermine in the pollen coat of the Asteraceae. Phylogenetic analyses combined with quantitative RT-PCR experiments allowed the identification of two homologous genes from Cichorium intybus (chicory) putatively involved in its metabolism. In vitro biochemical characterization of the two enzymes, named CiSHT1 and CiSHT2, confirmed the capability of recombinant proteins to synthesize spermine as well as spermidine derivatives. The wild-type metabolic phenotype was partially restored in an Arabidopsis sht mutant expressing CiSHT2. Strikingly, the transgenic plants also accumulated spermine derivatives that were absent in the wild-type. Overexpression of CiSHT2 in chicory hairy roots led to the accumulation of spermine derivatives, confirming its in vivo function. Complementary sequence analyses revealed the presence of an amino acid motif typical of the SHTs among the BAHD enzyme family. Our results highlight a recent neofunctionalization among the SHTs that has promoted the emergence of new phenolamides in the Asteraceae, which could potentially have contributed to the evolutionary success of this family.

PMID:
30169823
DOI:
10.1093/jxb/ery320

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