Are karrikin signaling mechanisms relevant to strigolactone perception?

Abstract

Karrikins found in smoke and the synthetic strigolactone GR24 induce similar developmental effects during early stages of Arabidopsis thaliana growth, including promotion of seed germination. Responses to karrikins and strigolactones are distinct at other growth stages, such as during the repression of axillary shoot growth. The F-box protein MAX2 is required for both signalling pathways. Two α-/β-hydrolase superfamily proteins, KAI2 and D14, control subsets of MAX2-regulated development. KAI2 is required for seed germination responses to karrikin and strigolactone treatments, while D14 mediates strigolactone-specific control of shoot branching. It is hypothesized that an orthologous pathway controls host-specific germination of the obligate parasitic Orobanchaceae.