Cloning and Characterization of the Classical Maize Mutant , Polytypic1

ECU Author/Contributor (non-ECU co-authors, if there are any, appear on document)

Anastasia Amoiroglou (Creator)

Institution

East Carolina University (ECU )

Web Site: http://www.ecu.edu/lib/

Abstract: Polytypic1 (Pt1) is a semi-dominant mutant in maize that affects inflorescence development. To understand how Pt1 functions in development , I examined the phenotype of Pt1 mutants in multiple inbred backgrounds. Pt1 defects are restricted to the inflorescence , but the severity of the phenotype is background dependent. In B73 and Mo17 inbreds , Pt1/+ mutants have severe floral defects; floral meristems initiate ectopic floral organs and Pt1/+ ears are female sterile. Pt1/+ tassels have similar defects as the ear , but are generally less severe. In B73 , Pt1/+ tassels contain fewer spikelets on the branches , and florets often produce extra floral organs. In Mo17 , Pt1/+ tassels produce silks. Because Pt1/+ ears are sterile in B73 and Mo17 , I could not examine the Pt1 homozygous phenotype. In A619 , however , the Pt1 phenotype is mild and Pt1/+ are female fertile. To identify the gene responsible for the Pt1 mutant phenotype , we pursued a positional cloning approach coupled with RNA-seq. I mapped Pt1 to a 6.8cM interval (~5Mbp) on chromosome 6 and performed RNA-sequencing to identify RNAs with changes in expression levels or sequence. The Pt1-containing interval contains 111 genes that are expressed in ear primordia , nine of which are differentially expressed. Notably , 13 MADs-box transcription factors , which are known floral regulators , are dramatically downregulated in Pt1 mutants. The characterization of Pt1 mutants will give insight into the mechanisms that underlie normal inflorescence development.

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Thesis

Language: English

Date: 2019

Keywords

maize

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