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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, MT
Wildfires 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 Communications

Volume

11

Article number

1264

Number

1264

Pagination

1264

ISSN

2041-1723

Department/School

School of Natural Sciences

Publisher

Nature Publishing Group

Place of publication

United Kingdom

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the biological sciences; Expanding knowledge in the environmental sciences

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