Microarray analysis of gene expression profile induced by pre-storage application of oxalic acid in tomato fruit under chilling stress

Abstract

To further illuminate the mechanism of oxalic acid (OA) alleviating chilling injury in tomato fruit under chilling stress, the differentially expressed genes were screened by using Affymetrix tomato GeneChip arrays after the mature-green tomato fruit were dipped in 10 mM OA solution for 10 min and then stored at 4 ± 0.5°C for 20 days. The results showed that 1,623 genes (540 up-regulated and 1,083 down-regulated genes) with more than two-fold differences in expression level were identified between OA treatment and the control. Differentially expressed genes mainly participate in signal transduction, defense, stress, primary metabolism, energy metabolism, cell-wall related, transcription related, protein metabolism and carotenoid metabolism. All differentially expressed genes were annotated by Gene Ontology (GO) annotation based on biological process, molecular functions and cellular components. Based on the level of molecular function, differentially expressed genes were found to be involved in binding, catalytic activity, lyase activity and peroxidase activity, while according to biological process categorization, those genes were involved in defense response, stress response, metabolic process, oxidation-reduction process, phosphorylation and cellular process. In addition, OA treatment could obviously up-regulate 1-aminocyclopropane-1-carboxylate synthase (ACS), 1-aminocyclopropane-1-carboxylate oxidase 1 (ACO), heat shock protein (HSP) and phosphoenolpyruvate carboxylase kinase gene and succinodehydrogenase gene expression, down-regulate pathogenesis-related proteins gene, sucrose synthetase and expansin gene expression. It was suggested that OA treatment improved the chilling tolerance in postharvest tomato fruit during storage at chilling temperature, due mainly to regulate genes expression such as ethylene biosynthesis, heat shock protein, pathogenesis-related protein and energy metabolism.