Genome-wide transcriptional analysis of maize endosperm in response to ae wx double mutations

Starch biosynthesis is important during endosperm development. Much has been known for the regulation of gene expression involved in starch synthesis, less information is available on the genome-wide expression profiles as a consequence of impaired starch synthesis. In this study, we examined the transcriptional responses through microarray analysis in an ae wx double-mutant with loss-of-function starch branching enzyme IIb (SBEIIb) and granule-bound starch synthase I (GBSSI). Through Gene Ontology enrichment analysis, we identified differentially expressed genes (DEGs) involved in chromatin organization and lipid transport. The DEGs also include alcohol dehydrogenase genes and pyruvate decarboxylase genes involved in sugar metabolism. In summary, the ae wx double mutations caused pleiotropic effects and transcriptional changes for a number of genes involved in metabolism, cellular response and organization. Therefore, a block in starch synthesis triggers transcriptional responses to favour the flux of excess carbohydrates into glycolysis, pentose phosphate pathway, and cell wall biosynthesis, but not toward the synthesis of alternative storage compounds.