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Divergent receptor proteins confer responses to different karrikins in two ephemeral weeds
journal contribution
posted on 2023-05-21, 09:41 authored by Sun, YK, Yao, J, Scaffidi, A, Melville, KT, Davies, SF, Bond, CS, Steven SmithSteven Smith, Flematti, GR, Waters, MTWildfires can encourage the establishment of invasive plants by releasing potent germination stimulants, such as karrikins. Seed germination of Brassica tournefortii, a noxious weed of Mediterranean climates, is strongly stimulated by KAR1, the archetypal karrikin produced from burning vegetation. In contrast, the closely-related yet non-fire-associated ephemeral Arabidopsis thaliana is unusual because it responds preferentially to KAR2. The α/β-hydrolase KARRIKIN INSENSITIVE 2 (KAI2) is the putative karrikin receptor identified in Arabidopsis. Here we show that B. tournefortii expresses three KAI2 homologues, and the most highly-expressed homologue is sufficient to confer enhanced responses to KAR1 relative to KAR2 when expressed in Arabidopsis. We identify two amino acid residues near the KAI2 active site that explain the ligand selectivity, and show that this combination has arisen independently multiple times within dicots. Our results suggest that duplication and diversification of KAI2 proteins could confer differential responses to chemical cues produced by environmental disturbance, including fire.
Funding
Australian Research Council
History
Publication title
Nature CommunicationsVolume
11Article number
1264Number
1264Pagination
1264ISSN
2041-1723Department/School
School of Natural SciencesPublisher
Nature Publishing GroupPlace of publication
United KingdomRepository Status
- Restricted