Transcriptome Profile Analysis of Sugarcane Responses to Sporisorium scitaminea Infection Using Solexa Sequencing Technology

To understand the molecular basis of sugarcane-smut interaction, it is important to identify sugarcane genes that respond to the pathogen attack. High-throughput tag-sequencing (tag-seq) analysis by Solexa technology was performed on sugarcane infected with Sporisorium scitaminea, which should have massively increased the amount of data available for transcriptome profile analysis. After mapping to sugarcane EST databases in NCBI, we obtained 2015 differentially expressed genes, of which 1125 were upregulated and 890 downregulated by infection. Gene ontology (GO) analysis revealed that the differentially expressed genes involve in many cellular processes. Pathway analysis revealed that metabolic pathways and ribosome function are significantly affected, where upregulation of expression dominates over downregulation. Differential expression of three candidate genes involved in MAP kinase signaling pathway, ScBAK1 (GenBank Accession number: KC857629), ScMapkk (GenBank Accession number: KC857627), and ScGloI (GenBank Accession number: KC857628), was confirmed by reverse transcription polymerase chain reaction (RT-PCR). Real-time quantitative PCR (qRT-PCR) analysis concluded that the expression of these genes were all up-regulated after the infection of S. scitaminea and may play a role in pathogen response in sugarcane. The present study provides insights into the molecular mechanism of sugarcane defense to S. scitaminea infection, leading to a more comprehensive understanding of sugarcane-smut interaction.