Quantification of karrikins in smoke water using ultra-high performance liquid chromatography–tandem mass spectrometry

Abstract

Background Karrikins (KARs) are plant growth regulators that promote seed germination and the subsequent growth and development of seedlings of many plant species. In nature they are generated and released by combustion of plant material and promote the restoration of burned ecosystems. Smoke water can be artificially prepared as a saturated extract of all substances in smoke produced by burning plants, and it has various horticultural and agricultural applications. Results We have developed, validated and applied the first fast, specific and sensitive method, based on ultra-high performance liquid chromatography–tandem mass spectrometry, for quantifying KARs in smoke water. To assist these efforts and further analyses, standards of the main KARs (which are not commercially available) were synthesized. Due to the complex matrix of smoke waters, two quantification approaches (standard dilution with a structural KAR analogue and standard addition) were compared. The standard addition method allowed absolute quantification of KARs in six of eight smoke water samples of diverse origins and ages. Conclusions Our findings reveal differences in both total and relative levels of KARs in smoke water, and indicate that differences in its KAR composition may be linked to variations in its bioactivity. Electronic supplementary material The online version of this article (10.1186/s13007-019-0467-z) contains supplementary material, which is available to authorized users.

Lotus japonicus karrikin receptors display divergent ligand-binding specificities and organ-dependent redundancy

“…The α/β-fold hydrolase KARRIKIN INSENSI-TIVE2 (KAI2) is thought to bind KARs, and interacts with the F-box protein MORE AXILLI-ARY GROWTH 2 (MAX2) that is required for ubiquitylation of repressor proteins via the Skp1-Cullin-F-box (SCF) complex [2][3][4][5][6][7][8][9]. There are six known KARs, of which KAR 1 is most abundant in smoke-water and most active on seed germination of fire-following plants [1,10,11], but Arabidopsis responds more strongly to KAR 2, which lacks the methyl group at the butenolide ring that is characteristic for KAR 1 [2,3,11]. Both KAR 1 and KAR 2 are commercially available and commonly used in research.…”

Lotus japonicus karrikin receptors display divergent ligand-binding specificities and organ-dependent redundancy

“…The α/β-fold hydrolase KARRIKIN INSENSITIVE2 (KAI2) is thought to bind KARs, and interacts with the F-box protein MORE AXILLIARY GROWTH 2 (MAX2) that is required for ubiquitylation of repressor proteins via the Skp1-Cullin-F-box (SCF) complex [2–9]. There are six known KARs, of which KAR 1 is most abundant in smoke-water and most active on seed germination of fire-following plants [1, 10, 11], but Arabidopsis responds more strongly to KAR 2 , which lacks the methyl group at the butenolide ring that is characteristic for KAR 1 [2, 3, 11]. Both KAR 1 and KAR 2 are commercially available and commonly used in research.…”

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

“…Karrikins comprise a family of butenolides with six known members. In samples of smoke water generated by burning grass straw, KAR 1 is the most abundant karrikin, whereas KAR 2 is six times less abundant 4 , although these proportions may differ depending on source material, preparation method, age and storage conditions 5 . These two analogues differ only by the presence of a methyl group on the butenolide ring in KAR 1 , which is absent in KAR 2 ( Supplementary Fig.…”