Gene Expression Profiling in Short-Term Imbibition of Wheat: Tools for Dissecting of Pasting Properties of Imbibed Wheat Seeds.

ABSTRACT

Germination of wheat maximizes phytochemical content and antioxidant activity while altering chemical composition, gluten content, and pasting properties. This study investigated the effect of short-term imbibition on gene expression profiles and the physical and functional characteristics of wheat. Changes in gene expression profiles of wheat during short-term imbibition (0, 16, and 24 hr) were evaluated by DNA microarray analysis. Gene Ontology (GO) analysis was carried out to categorize the function of genes with altered expression. Genes related to cellulose and cell wall synthesis were upregulated by imbibition for 16 hr, whereas those associated with polysaccharide catabolism and nucleosome assembly were upregulated in the subsequent 8 hr. The genes related to proteases and gluten were expressed in dry seeds but disappeared after 16 hr of imbibition. Genes encoding α-amylase were not expressed in dry seeds whereas those encoding ß-amylase were expressed in dry seeds and downregulated by imbibition. According to quantitative real-time PCR and enzymatic activity assay, α-Amylase expression increased by imbibition and reached a maximum 24 hr after imbibition, with a corresponding increase in enzymatic activity. Pasting properties of flour made from wheat seeds imbibed for different times were decreased when seeds were imbibed for over 16 hr, by examination with Rapid Visco Analyzer. Gluten content did not significantly change until 24-hr imbibition, although expression of genes encoding gliadin and glutenin disappeared by 16-hr imbibition. The data indicated that it was possible to use 16-hr imbibed wheat, with up to the 50% w/w replacement of nonimbibed wheat.