1. Identifying Mu Insertions in Nutrient Transport-related Genes in the UniformMu Maize Population Overview: Research presented here tests the hypotheses that insertion of a Mu transposable element into any of the selected genes will cause a loss of function that results in a distinct mutant phenotype. The UniformMu maize population is a resource developed by introgressing the highly transposon-mutagenic line Robertson’s Mutator into the phenotypically-uniform inbred W22. This population provides the ability to identify and map Mu insertions, allowing researchers to select and characterize lines harboring mutations in genes of interest. Here we use both a forward and reverse genetics approach to identify insertions in genes potentially affecting nutrient transport. To this end, we attempt to associate insertions with mutant phenotypes through co-segregational analyses. Stephanie M. Locke, Brent. A. O’Brien, Ryan Gannon, Johnathan Saunders, Laura Morales, Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, FL, 32611 References: McCarty, D.R., Settles, A.M., Suzuki, M., Tan, B.C., and Latshaw, S. et al. (2005). Steady-state transposon mutagenesis in inbred maize. Plant J. 44: 52- 61.  Localizes to the plasmodesmata and is predicted to bind callose, which is deposited at the sieve plate in response to injury and pathogen infection.  GRMZM2G125241 Plasmodesmata callose binding protein 4 (PDCB4)  ABC (ATP binding cassette) transporters are transmembrane proteins that utilize the energy of ATP hydrolysis to pump substrate across the membrane against a concentration gradient.  GRMZM2G156630 ABC-type transporter  Primarily functions in carbohydrate binding  In A. Thaliana, this gene was found to be a N-terminal protein involved in myristoylation and control responses to phloem damage.  GRMZM2G010855 Phloem protein 2A13 (PP2 A13)  This gene functions in carbohydrate transmembrane transporter activity.  GRMZM2G160504  GRMZM2G160460 Solute carrier family 2, facilitated glucose transporter member 8 (SLC2A8)  Hydrolyzes sucrose to fructose and glucose in the cytoplasm  GRMZM2G084940 Plant neutral invertase family protein  SCF23 represents integral membrane proteins that transport organic molecules and inorganic ions.  GRMZM2G437859 Solute carrier family 23 member 2 (SCF23) Reverse Genetics Forward Genetics Family 011S-2189 Phenotype = wilty Insertions Tested Segregation/genotypes Insertions Tested with main phenotypes Co-segregation Mitochondrial transcription termination factor family protein Long-chain acyl-CoA synthetase 7 Hercules receptor kinase 2 Protein of unknown function (DUF3537) Peptidase M1 family protein PapD-like superfamily protein Sec-independent periplasmic protein translocase Cellulose synthase-like D3 Succinate dehydrogenase 1-1 Segregation/genotypes KO with phenotype Co-segregation of Prominent Phenotypes WT, Het, and Homozygous All WT WT, and Homozygous NO -- Empty pericarp (ep) Embryo lethal (emb) Leaf discoloration Defective kernel (dek), Rough kernel (rgh), ep, and emb Small kernel (smk), ep, and emb smk and emb ep and dek smk WT, Het, and Homozygous PCR inconclusive to date All Het or WT ( GRMZM2G160504) All Het (GRMZM2G160460) WT, Het, and Homozygous All Het WT, Het, and Homozygous ? NO (other effects possible) ep smk Leaf discoloration emb Phenotype Examples NO (other effects possible) NO (other effects possible) NO (other effects possible) NO (other effects possible) Wayne T. Avigne, Donald McCarty, Charles Hunter, and Karen E. Koch