Grant: Discovery Grants Program - Individual

Cytokinins as omni-hormones: their roles from plants to other life kingdoms The cytokinins (CKs) are classic plant hormones that have dramatic impact on processes such as growth, nutrient acquisition, ageing, branching flowering, seed yield, and root growth. However, they are not uniquely associated with plants and are found in: bacteria, algae, fungi, insects, nematodes, fish and even mammals, including humans. Interactions between these organisms and plants reveal roles for CKs in parasitic, pathogenic and symbiotic associations. But, since CKs are ancient molecules that pre-date plants, these insights may only represent a small number of functions they have among other life kingdoms. Therefore, for our long-term goal we are taking our studies of CKs beyond plants and into other kingdoms. To this end, we will study CK production and their impacts on the development of model species of fungi, protists, and insects. CKs and development of a model fungus - We have studied plant-fungi interactions extensively with the presumption that fungal CKs were produced to control plants. Yet, our recent evidence suggests that CKs may impact development of the fungus itself. Surprisingly, minimal work has tested this. Sordaria is a multicellular, model fungus for studying chemical signaling. Our lab will use a selection of Sordaria developmental mutants from other labs and compare them to mutants we generate ourselves that have altered CK synthesis. This will enable study of CKs throughout fungal development in conjunction with an assessment of energy metabolism, hormonal regulation, and growth processes. CK signaling and cellular organization in a model protist - Known sometimes as a "social amoeba", Dictyostelium discoideum, sits in evolution between the separation of plants and animals and can therefore reveal the diverging roles of CKs. In its unusual life cycle, cells can exist as isolated amoebae or they can stream together to form multicellular organisms. We will study the Dictyostelium life cycle in wildtype and gene-edited mutant strains with altered CK synthesis or metabolism. CK profiles will be linked with phenotypic and biochemical changes among single celled-amoebae and during multicellular organization. Production and impacts of CKs in a model insect - We found CKs in insects and we know they inject them into plants - but we do not know if they can make their own CKs. Many think that CKs come from bacteria living within the insect. We will use the fruit fly (Drosophila) model to see if there are CK genes in insects. We observed unusual CK patterns in fruit flies and we generated mutants by changing a gene we believe codes for CK biosynthesis. We will look at gene expression, protein levels and CK profiles in mutants that either turn down, or turn up, the gene's expression. Results will show if a CK pathway is functional in insects and give clues about any hormonal control that CKs may have in insect development.