CAREER: Karrikin and strigolactone signaling mechanisms in Arabidopsis

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DAVID C NELSONPROPOSAL IOS-1350561CAREER: Karrikin and strigolactone signaling mechanisms in ArabidopsisKarrikins are a recently discovered class of compounds found in smoke that activate germination of many plant species after fire. Strigolactones comprise a family of plant hormones that regulate shoot branching, root architecture, and cambial growth. Strigolactones also trigger germination of the highly destructive parasitic weeds, broomrape and witchweed, and promote symbiotic associations with arbuscular mycorrhizal fungi. Understanding the molecular mechanisms by which karrikins and strigolactones control plant growth may enable a new wave of innovation in crop development and weed control.Plants recognize both karrikins and strigolactones through a genetic pathway that requires the F-box protein MAX2. F-box proteins have central roles in several plant hormone signaling systems, and act by targeting specific protein substrates for degradation. The targets of MAX2 have long remained elusive and as such represent a critical roadblock to understanding the mechanism of karrikin and strigolactone signaling. A genetic screen has now led to the identification of a candidate target, SUPPRESSOR OF MAX2 1 (SMAX1), which regulates seed germination and seedling growth. SMAX1 is a member of an uncharacterized family of eight genes in the model plant Arabidopsis thaliana. In this project genetic and biochemical approaches will be used to determine 1) how other genes in the SMAX1 family contribute to plant development; 2) the molecular function and regulation of SMAX1 protein; and 3) the protein interacting partners of SMAX1 and MAX2. These experiments will reveal how the SMAX1 family acts in karrikin and strigolactone signaling and whether SMAX1 is a target of MAX2. A postdoctoral researcher,graduate student, and several undergraduates will be trained for careers in science-related fields. Two projects will be initiated to improve undergraduate retention in science-related careers and enhance K-12 STEM education. The discoveries from this project will be disseminated through publications in peer-reviewed journals and presentations at scientific conferences.