RNA-seq for comparative transcript profiling of kenaf under salinity stress.

Kenaf (Hibiscus cannabinus L.) is an economically important global natural fiber crop. As a consequence of the increased demand for food crops and the reduction of available arable land, kenaf cultivation has increasingly shifted to saline and alkaline land. To investigate the molecular mechanism of salinity tolerance in kenaf, we performed Illumina high-throughput RNA sequencing on shoot tips of kenaf and identified 71,318 unigenes, which were annotated using four different protein databases. In total, 2,384 differentially expressed genes (DEGs) were identified between the salt-stressed and the control plants, 1,702 of these transcripts were up-regulated and 683 transcripts were down-regulated. Thirty-seven transcripts belonging to 15 transcription-factor families that respond to salt stress were identified. Gene ontology function enrichment analysis revealed that the genes encoding antioxidant enzymes were up-regulated. The amino acid metabolism and carbohydrate metabolism pathways were highly enriched among these DEGs under salt stress conditions. In order to confirm the RNA-seq data, we randomly selected 20 unigenes for analysis using a quntitative real-time polymerase chain reaction. Our study not only provided the large-scale assessment of transcriptome resources of kenaf but also guidelines for understanding the mechanism underlying salt stress responses in kenaf.