Journal Article

Divergent receptor proteins confer responses to different karrikins in two ephemeral weeds

Sun, Yueming Kelly, Waters, Mark T., Melville, Kim T., Bond, Charles S., Flematti, Gavin R., Yao, Jiaren, Scaffidi, Adrian, Davies, Sabrina F., Smith, Steven M.

2020

Overview

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 KAR 1 , 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 KAR 2 . 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 KAR 1 relative to KAR 2 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. Karrikins are germination stimulants perceived by KAI2 in Arabidopsis . Here the authors show that Brassica tournefortii , a close relative to Arabidopsis , has multiple copies of KAI2 with amino acid substitutions that confer responsiveness to the specific karrikin compounds found in wildfire smoke.

• Publisher: Nature Publishing Group UK,Nature Publishing Group,Nature Portfolio
• Subject: 38/88 / 49/91 / 631/208/2491 / 631/449/1741 / 631/449/2675 / 631/92/613 / 82/80 / 82/83 / Amino acids / Arabidopsis - drug effects / Arabidopsis - genetics / Arabidopsis - metabolism / Arabidopsis Proteins / Arabidopsis thaliana / Brassica / Brassica - drug effects / Brassica - genetics / Brassica - metabolism / Brassica tournefortii / Burning / Carrier Proteins - drug effects / Carrier Proteins - metabolism / Catalytic Domain / Chemical stimuli / Divergence / Ecosystem biology / Fires / Furans - pharmacology / Gene Expression Regulation, Plant / Genomes / Germination / Germination - drug effects / Germination - physiology / Homology / Humanities and Social Sciences / Hydrolase / Hydrolases - genetics / Hydrolases - metabolism / Invasive plants / Ligands / Magnoliopsida / multidisciplinary / Plant Proteins - drug effects / Plant Proteins - genetics / Plant Proteins - metabolism / Plant Weeds - drug effects / Plant Weeds - metabolism / Proteins / Pyrans - pharmacology / Science / Science (multidisciplinary) / Seed germination / Seedlings / Seeds / Seeds - drug effects / Seeds - physiology / Selectivity / Sequence Analysis, Protein / Stimulants / Transcriptome / Weeds / Wildfires