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Uncovering tasselsheath3. A Genomic and Phenotypic Analysis of a Maize Floral Mutant.

In the modern era, maize has become the most successful crop grown in the United States. According to the USDA over 90 million acres of land are planted to corn and 96.2% of the U.S feed grain production is made up of the cereal. Part of the success of maize is due to its floral architecture, and its pollination technique in which the flower opens, exposing stamens containing pollen into the air. A unique organ called the lodicule functions as a release mechanism, forcing the flower to open. Lodicules from grasses and eudicot petals are homologous, yet there is little known of how lodicules are specified during development. Other examples of maize mutants with defects in the lodicule have been discovered including silky1, bearded ear, and sterile tassel silky ear1, but there has been no definitive pathway found that specifies the developmental characteristics of the lodicule. My work has focused on a maize mutant, tasselsheath3 (tsh3), which displays a floral phenotype in the lodicule whorl to better understand this organ. Analysis of tsh3 was separated into two sections: a quantitative phenotypic analysis of the tsh3 floral mutant phenotype, compared to a previously unstudied floral phenotype of tasselsheath1 (tsh1), as well as a tsh1; tsh3 double mutant. I found that lodicule morphology and lodicule number was affected in tsh1, tsh3, and the tsh1; tsh3 mutants. Section two was to identify the single gene that was disrupted in tsh3 mutants. Through both fine mapping and next generation sequencing I was able to localize tsh3 to a region between 148.1mbp and 152.8mbp on chromosome 6. This 4.7mbp region of interest contains 64 protein coding genes. As evidenced by the phenotyping data, tsh3 plays a role specifying lodicule identity during development and has been localized to this region of chromosome 6 on the maize genome.