ROLE OF CYTOKININ IN REGULATING ABIOTIC STRESS RESISTANCE IN RICE

The overall goal of this project is to determine the role that cytokinin plays in regulating drought and salt stress responses in rice, with a particular focus on developing cytokinin-based strategies to alleviate these abiotic stresses in crops. For this purpose, we will take a mutant-based approach, taking advantage of lines we have generated in rice that confer hypo- and hyper-sensitivity to cytokinin. Our Aims are as follows:Aim 1. Generation and characterization of cytokinin hypersensitive lines. We hypothesize that loss-of-function lines of the KMD and type-A RR families will result in varying degrees of cytokinin hypersensitivity. We will therefore complete the generation of mutant lines in these gene families by employing a CRISPR-Cas9-based approach, and characterize the effects of these mutations on growth and development as well as on cytokinin sensitivity using physiological and molecular assays.Aim 2. Determine the roles cytokinin signaling plays in the drought and salt stress responses. We will test the hypothesis that increased cytokinin sensitivity will confer increased resistance to abiotic stresses in rice. For this purpose, we will characterize cytokinin hypo- and hypersensitive mutant lines for their sensitivity to drought and salt stress at seedling, pre-anthesis, and post-anthesis growth stages in rice, making use of physiological, biochemical, and molecular assays.Aim 3. Identify gene regulatory networks by which cytokinin mediates drought and salt stress resistance We hypothesize that cytokinin initiates drought-stress specific, salt-stress specific, and co-response pathways. We will test this hypothesis by performing RNA-seq analysis using our stress-resistant mutant lines, comparing their response to the wild type and to each other, and generating networks to uncover individual and co-responsive pathways. Results will suggest potential mechanisms by which cytokinin modulates these abiotic stress responses.