KAI2-and MAX2-mediated responses to karrikins and strigolactones are largely independent of HY5 in Arabidopsis seedlings
Document Type: Journal Article
Author(s): M. T. Waters; S. M. Smith
Publication Year: 2013

Cataloging Information

  • Australia
  • chemical compounds
  • HY5
  • KAI2
  • karrikin
  • light
  • photomorphogenesis
  • seed germination
  • seedlings
  • smoke effects
  • smoke management
  • Strigolactone
  • International
Record Maintained By:
Record Last Modified: June 1, 2018
FRAMES Record Number: 52170
Tall Timbers Record Number: 29235
TTRS Location Status: Not in file
TTRS Call Number: Available
TTRS Abstract Status: Okay, Fair use, Reproduced by permission

This bibliographic record was either created or modified by the Tall Timbers Research Station and Land Conservancy and is provided without charge to promote research and education in Fire Ecology. The E.V. Komarek Fire Ecology Database is the intellectual property of the Tall Timbers Research Station and Land Conservancy.


Karrikins are butenolide compounds released from burning vegetation that stimulate seed germination and enhance seedling photomorphogenesis. Strigolactones are structurally similar plant hormones that regulate shoot and root development, and promote the germination of parasitic weed seeds. In Arabidopsis, the F-box protein MAX2 is required for responses to karrikins and strigolactones, and the a/b hydrolase KAI2 is necessary for responses to karrikins. Both MAX2 and KAI2 are essential for normal light-dependent seedling development. The bZIP transcription factor HY5 acts downstream of multiple photoreceptors and promotes photomorphogenesis, but its relationship with MAX2 and KAI2 in terms of seedling development and responses to karrikins and strigolactones is poorly defined. Here, we demonstrate that HY5 action is genetically separable from that of MAX2 and KAI2. While hy5 mutants have weak hypocotyl elongation responses to karrikins and the artificial strigolactone GR24, they have normal transcriptional responses, suggesting that HY5 is not involved in perception or action of karrikins or strigolactones. Furthermore, we show that overexpression of KAI2 is sufficient to enhance responses to both karrikins and GR24 in wild-type seedlings, and that KAI2 overexpression partially suppresses the hy5 long hypocotyl phenotype. These results suggest that KAI2 and MAX2 define a regulatory pathway that largely operates independently of HY5 to mediate seedling responses to abiotic signals such as smoke and light. © The Authors 2012. Published by the Molecular Plant Shanghai Editorial Office in association with Oxford University Press on behalf of CSPB and IPPE, SIBS, CAS.

Waters, M. T., and S. M. Smith. 2013. KAI2-and MAX2-mediated responses to karrikins and strigolactones are largely independent of HY5 in Arabidopsis seedlings. Molecular Plant, v. 6, no. 1, p. 63-75. 10.1093/mp/sss127.