multicellular organisms sense zinc and consequently regulate zinc transport is largely unknown. Themain goal of our research is to understand how a family of cell wall-associated receptor kinases (WAK)and WAK-like (WAKL) kinases function in cell-cell and cell-environment communications. We havediscovered that WAKL4, a WAK/WAKL family member, plays a critical role in Arabidopsis zinc sensing.Our objective in this application is to elucidate the mechanisms of how plants use WAKL4 to monitorextracellular zinc conditions and to regulate zinc transport. Our central hypothesis is that WAKL4, as areceptor kinase, is one of the key regulatory components in zinc signaling. We propose to test thishypothesis to identify key regulators in Arabidopsis zinc signaling.
In Aim 1, we will test if zinc-inducedtissue-specific WAKL4 expression plays a role in zinc sensing and zinc transport by identifying the actualcomponents that control zinc-induced WAKL4 expression. A combination of biochemical, genetic andbioinformatic approaches will be used to identify and to determine the roles of the regulatorycomponents.
In Aim 2, we will use suppressor screening to identity other critical genes in the WAKL4-mediated zinc signaling. The genetic screening is based on the fact that in the absence of WAKL4, zinctransporter genes fail to respond to external zinc depletion. We will identify mutants whose zinctransporter genes, in absence of WAKL4, remain responding to zinc deficiency. WAKL4 is the firstreceptor kinase suggested as having a role in mineral sensing and regulation. Our proposed studies areexpected to provide critical information in understanding how Arabidopsis uses receptor kinases to senseand respond to zinc, and to significantly advance the understanding of how WAK/WAKL memberscommunicate between the extracellular and intracellular compartments.Relevance to Public Health: Zinc is an essential micronutrient for all organisms and its deficiency is awell-known human-health problem. Our contribution here is expected to be a detailed understanding ofhow an extracellular matrix-linked receptor kinase plays a role in plant zinc sensing and transport. Thiscontribution is expected to provide the knowledge needed to significantly improve edible plants as betterdietary zinc sources for both animals and humans.
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