Comparative Transcriptome Profiling of Resistant and Susceptible Sugarcane Cultivars in Response to Infection by Xanthomonas albilineans

Abstract

Sugarcane (<i>Saccharum</i> spp. hybrids) is a major source of sugar and renewable bioenergy crop worldwide and suffers serious yield losses due to many pathogen infections. Leaf scald caused by <i>Xanthomonas albilineans</i> is a major bacterial disease of sugarcane in most sugarcane-planting countries. The molecular mechanisms of resistance to leaf scald in this plant are, however, still unclear. We performed a comparative transcriptome analysis between resistant (LCP 85-384) and susceptible (ROC20) sugarcane cultivars infected by <i>X. albilineans</i> using the RNA-seq platform. 24 cDNA libraries were generated with RNA isolated at four time points (0, 24, 48, and 72 h post inoculation) from the two cultivars with three biological replicates. A total of 105,783 differentially expressed genes (DEGs) were identified in both cultivars and the most upregulated and downregulated DEGs were annotated for the processes of the metabolic and single-organism categories, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of the 7612 DEGs showed that plant-pathogen interaction, spliceosome, glutathione metabolism, protein processing in endoplasmic reticulum, and plant hormone signal transduction contributed to sugarcane's response to <i>X. albilineans</i> infection. Subsequently, relative expression levels of ten DEGs determined by quantitative reverse transcription-PCR (qRT-PCR), in addition to RNA-Seq data, indicated that different plant hormone (auxin and ethylene) signal transduction pathways play essential roles in sugarcane infected by <i>X. albilineans.</i> In conclusion, our results provide, for the first time, valuable information regarding the transcriptome changes in sugarcane in response to infection by <i>X. albilineans</i>, which contribute to the understanding of the molecular mechanisms underlying the interactions between sugarcane and this pathogen and provide important clues for further characterization of leaf scald resistance in sugarcane.