Abstract

Previous proteomic studies have shown maize cob tissue to have an essential role in pathogen defense. Currently, there are no studies published regarding neither maize cob metabolomic profiles nor an accepted method of metabolite extraction from cob. This study assesses the reproducibility of metabolite extraction from the cobs of fungal pathogen -resistant and -susceptible cultivars. Hand grinding, mechanical ball-milling and adapted focused acoustics methods of tissue homogenization were preformed and examined via Liquid Chromatography-Mass Spectrometry (LC-MS). Among tested methods, the manual grinding with a mortar and pestle was found to be the most reproducible and efficient. All methods showed good reproducibility within but provided statistically different sets of metabolite features when compared across methods. A suitable extraction method for future cob metabolomics experiments was ascertained, however careful results validation will be needed to distinguish between true biological phenomenon and artifacts rising from a methodology bias. For the first time, maize cob metabolites have been successfully extracted and detected, establishing a reproducible method for further metabolomic profiling of cob defense metabolites.

Key words: Liquid Chromatography-Mass Spectrometry (LC-MS), metabolomics, Aspergillus flavus, homogenization, extraction, grinding.