Analysis of novel components promoting asymmetric division in maize

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Plants and animals are composed of many cell types, and each of these cell types have specialized roles so that together they make a functional and efficient organism. Each cell within a multi-cellular organism must be patterned correctly; that is, each cell must be placed in the correct place with respect to its neighboring cells. The process that determines cell placement is asymmetric cell division. This proposal addresses the mechanism of asymmetric cell division in plants, using maize (corn) as a plant model system. The roles of specific proteins during asymmetric division will be investigated, including a motor protein (myosin) and a family of unknown proteins. Additionally, new mutants that fail to correctly carry out asymmetric division have been identified. These new mutants will be used to identify novel proteins important for this process, as well as an undergraduate genetics training program. Broader impacts for the project include a microscopy workshop aimed at training researchers in image analysis. Asymmetric cell division is tied to cell fate determination and tissue patterning, and is critical for proper plant development and function. Asymmetric division occurs in three steps: cell polarization, division plane establishment and maintenance, and cytokinesis. Maize stomatal development provides an excellent model system for investigating plant cell asymmetric division. The functional roles of new molecules promoting division asymmetry will be investigated. Candidates that are known or predicted to interact with the actin cytoskeleton will be a primary focus. This focus will help determine how proteins in the pathway communicate with the cytoskeleton to orchestrate the complex process of asymmetric division. Objective 1 will determine the role of a class XI myosin in asymmetric division. Mutants in this myosin show abnormal asymmetric division in the stomata. Objective 2 will determine the role of a family of unknown proteins in asymmetric division. These proteins interact with a receptor-like protein (PAN2) previously shown to be required for asymmetric division in stomata, and Crispr-Cas9 generated knockouts of these mutants show aberrant divisions. Objective 3 entails the retesting and mapping via of novel mutants isolated via an enhancer screen. Retesting, segregation analyses and mapping via next generation sequencing will be used for training of undergraduate researchers. Broader impacts for the project include a microscopy workshop aimed at training researchers in image analysis.This research is jointly supported by IOS, MCB and the ROL venture fund.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.