Speaker: Dirk Winkelman, graduate student in the Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology

Major professors: Marna Yandeau-Nelson, genetics, development and cell biology associate professor; and Basil Nikolau, Frances M. Craig Professor Emeritus

Title: A multi-disciplinary approach to investigate maize very long chain fatty acid elongation and cuticular wax biosynthesis

Abstract: In plants, very-long-chain fatty acids (VLCFAs) of 20 or more carbon chain lengths serve as the precursors to the waxes that are incorporated into the cuticle. The cuticle is a hydrophobic barrier that protects the plant from both biotic and abiotic stresses, including pathogen invasion, insect pressure, and drought. The VLCFA precursors are produced by the fatty acid elongase (FAE) system, which is a four step, cyclical pathway that elongates a preexisting acyl-CoA by two carbon atoms with every turn of the FAE cycle. We utilized Saccharomyces cerevisiae to overcome the genetic redundancy of the maize FAE (ZmFAE) system that includes 28 genes encoding the key condensation step. We generated strains that express unique iterations of the ZmFAE pathway in the absence of the endogenous yeast FAE (ScFAE) enzymes, allowing us to characterize the substrate specificities of each version of the ZmFAE. Chain length specificity of the ZmFAE system may also be mediated by the maize Glossy2 (Gl2) and Glossy2-like (Gl2-like) genes. To further assess the functionalities of GL2 and GL2-LIKE, we 1) expressed these proteins in our yeast strains that express the ZmFAE pathway and compared resultant VLCFA profiles; and 2) characterized Gl2 and Gl2-likein planta via cuticular wax profiling and functional characterizations of plants carrying mutant gl2 and gl2-like alleles. Collectively, this work establishes the substrate specificities of different iterations of the ZmFAE system and shows that Gl2 and Gl2-like have unique impacts on fatty acid elongation and wax biosynthesis, as well as cuticle function. 

Zoom link: https://iastate.zoom.us/j/91533270393?pwd=YAkz6WGgUeXFhWLPLoqoJu3DPLmjbG.1