Portfolio

Project 1: Investigation of the molecular basis of heterosis using proteomics and transcriptomics

Heterosis refers to the superior performance of F1 hybrids relative to their inbred parents. The agriculture industry has utilized this phenomenon in both crop and livestock breeding for centuries, despite the additional time and labor required for hybrid breeding programs. The molecular underpinnings of heterosis have persisted as an unsolved classical problem in biology since its initial report by Charles Darwin. Studies have found few instances of gene expression outside mid-parental range in hybrids, providing little explanation for the disparity in phenotype. I conducted paired proteomics and transcriptomics to compare expression levels in maize hybrids to those of their inbred parents.

Visualizing protein and mRNA expression patterns in hybrids

Correlation between protein levels and heterosis levels

Comparison of precision in proteomics versus transcriptomics

Project 2: Comparison of maize genome annotation versions

Several versions of the maize genome have been published to date, with some containing more genes than others. This presents a challenge for proteomics studies, as choosing which genome version to search against can alter the conclusions of the study. I sought to develop a new gene set that represented the nonredundant sum of each version. Using a protein preparation from maize tissue, I conducted multiplexed tandem mass tag labeling and mass spectrometry and searched against four published genome annotations: NCBI, Uniprot, v2, and v4.

Identifying shared and unique gene sets

Project 3: Characterization of a predicted glycosyltransferase enzyme

Pectins are the most complex polysaccharides of plant cell walls, with an estimated 67 transferases expected to be involved in their biosynthesis, most of which have not been identified. β-1,4-Galactans constitute a major part of pectin as side chains of rhamnogalacturonan-I (RG-I). Glycosyltransferase family GT92 comprises three β-1,4-galactan synthases (GALS1-3) in Arabidopsis, which catalyze the addition of galactose units from UDP-Gal to growing β-1,4-galactan chains. I characterized a highly conserved gene encoding a putative glycosyltransferase related to GT family 92, Galactan Synthase- Like (GSL). Characterization of the GSL enzyme could provide an approach to engineering plants with an increased ratio of C6 to C5 sugars, a key objective for production of second-generation biofuel.

Immunolabeling cell wall epitopes in mutants

High-performance anion exchange chromatography analysis of mutants