Differentially expressed genes and in silico analysis in response to ozone (O3) stress of soybean leaves

Abstract

This study was conducted to identify specific/predominant genes of soybean leaves fumigated with ozone (O3) in the fifth trifoliolate stage. Leaves were exposed to O3 at concentrations of 120 and 200 ppb for four hours on each of five consecutive days. We compared the expression levels of mRNA fragments in untreated versus treated leaves based on, the different banding patterns obtained by agarose gel electrophoresis. These patterns revealed that 408 transcripts were differentially expressed between treated and untreated leaves; 153 transcripts were up-regulated in soybean leaves fumigated with O3 and 225 transcripts were down-regulated. The putative functions of the expressed sequence tags (ESTs) were identified using BLASTX. Of 408 transcripts, 186 differentially expressed genes (DEGs) in response to O3 significantly matched previously known genes. To identify the functional modules of DEGs and protein domains, we used the Swiss-Port IPROClass database. The DEGs of soybean leaves in response to O3 were annotated by cross-species analysis with Arabidopsis. The Cytoscape plugin ClueGO was used to identify six network pathways of enrichment over-represented significantly. Most of the O3 responsive genes identified in this study were related to other biotic and abiotic stresses. The characterization of ESTs enables better understanding of the molecular basis of O3 responses.