Divergent receptor proteins confer responses to different karrikins in two ephemeral weeds
journal contribution
posted on 2023-05-21, 09:41authored bySun, 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