eCite Digital Repository

Karrikins discovered in smoke trigger Arabidopsis seed germination by a mechanism requiring gibberellic acid synthesis and light

Citation

Nelson, DC and Riseborough, J-A and Flematti, GR and Stevens, J and Ghisalberti, EL and Dixon, KW and Smith, SM, Karrikins discovered in smoke trigger Arabidopsis seed germination by a mechanism requiring gibberellic acid synthesis and light, Plant Physiology, 149, (2) pp. 863-873. ISSN 0032-0889 (2009) [Refereed Article]

Copyright Statement

2009 American Society of Plant Biologists. All rights reserved.

DOI: doi:10.1104/pp.108.131516

Abstract

Discovery of the primary seed germination stimulant in smoke, 3-methyl-2H-furo[2,3-c]pyran-2-one (KAR1), has resulted in identification of a family of structurally related plant growth regulators, karrikins. KAR1 acts as a key germination trigger for many species from fire-prone, Mediterranean climates, but a molecular mechanism for this response remains unknown. We demonstrate that Arabidopsis (Arabidopsis thaliana), an ephemeral of the temperate northern hemisphere that has never, to our knowledge, been reported to be responsive to fire or smoke, rapidly and sensitively perceives karrikins. Thus, these signaling molecules may have greater significance among angiosperms than previously realized. Karrikins can trigger germination of primary dormant Arabidopsis seeds far more effectively than known phytohormones or the structurally related strigolactone GR-24. Natural variation and depth of seed dormancy affect the degree of KAR1 stimulation. Analysis of phytohormone mutant germination reveals suppression of KAR1 responses by abscisic acid and a requirement for gibberellin (GA) synthesis. The reduced germination of sleepy1 mutants is partially recovered by KAR1, which suggests that germination enhancement by karrikin is only partly DELLA dependent. While KAR1 has little effect on sensitivity to exogenous GA, it enhances expression of the GA biosynthetic genes GA3ox1 and GA3ox2 during seed imbibition. Neither abscisic acid nor GA levels in seed are appreciably affected by KAR1 treatment prior to radicle emergence, despite marked differences in germination outcome. KAR1 stimulation of Arabidopsis germination is light-dependent and reversible by far-red exposure, although limited induction of GA3ox1 still occurs in the dark. The observed requirements for light and GA biosynthesis provide the first insights into the karrikin mode of action.

Item Details

Item Type:Refereed Article
Keywords:karrikins, smoke, arabidopsis thaliana, seed germination, gibberelic acid synthesis, light
Research Division:Biological Sciences
Research Group:Plant Biology
Research Field:Plant Physiology
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Biological Sciences
Author:Smith, SM (Professor Steven Smith)
ID Code:101478
Year Published:2009
Web of Science® Times Cited:125
Deposited By:Plant Science
Deposited On:2015-06-24
Last Modified:2015-09-22
Downloads:0

Repository Staff Only: item control page