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Science. 2015 Jul 31;349(6247):540-3. doi: 10.1126/science.aab1140.

PLANT EVOLUTION. Convergent evolution of strigolactone perception enabled host detection in parasitic plants.

Author information

1
Department of Genetics, University of Georgia, Athens, GA 30602, USA.
2
School of Chemistry and Biochemistry, The University of Western Australia, Crawley, Western Australia 6009, Australia.
3
RIKEN Center for Sustainable Resource Science, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
4
Department of Plant Pathology, Physiology, and Weed Science, Virginia Tech, Blacksburg, VA 24061, USA.

Abstract

Obligate parasitic plants in the Orobanchaceae germinate after sensing plant hormones, strigolactones, exuded from host roots. In Arabidopsis thaliana, the α/β-hydrolase D14 acts as a strigolactone receptor that controls shoot branching, whereas its ancestral paralog, KAI2, mediates karrikin-specific germination responses. We observed that KAI2, but not D14, is present at higher copy numbers in parasitic species than in nonparasitic relatives. KAI2 paralogs in parasites are distributed into three phylogenetic clades. The fastest-evolving clade, KAI2d, contains the majority of KAI2 paralogs. Homology models predict that the ligand-binding pockets of KAI2d resemble D14. KAI2d transgenes confer strigolactone-specific germination responses to Arabidopsis thaliana. Thus, the KAI2 paralogs D14 and KAI2d underwent convergent evolution of strigolactone recognition, respectively enabling developmental responses to strigolactones in angiosperms and host detection in parasites.

PMID:
26228149
DOI:
10.1126/science.aab1140
[Indexed for MEDLINE]
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