Comparative Transcriptome Analysis of Seedling Stage of Two Sorghum Cultivars Under Salt Stress

Soil salinity is one of the major abiotic stresses restricting crop production. Mechanisms of salt response have been intensively studied in model plants such as Arabidopsis and rice, but are rarely known in sorghum. In this study, we compared the transcriptome profiles between two cultivars with different salt tolerance under salt treatment (0.8% NaCl) for 0, 48, and 72 h. On average, about 243.9 million clean reads, representing 32.4 thousand transcripts and 26.4 thousand unigenes with 829 new genes were detected in each library. Also, over 112,000 single nucleotide polymorphisms were identified, which may supply useful resources for marker development. In total, 5647 differentially expressed genes (DEGs) were identified from all of the comparisons. Functional annotation analysis indicated that expression of genes in transcriptional regulation, signal transduction, and secondary metabolism changed significantly between the two varieties under salt stress, and hundreds of genes involved in the salt stress response were differentially expressed, especially genes encoding receptors like kinases and transcription factors. Besides, qRT-PCR analysis of expression profiles of the selected DEGs was in keeping with the results from RNA-seq analysis. Based on the findings, we proposed several candidate genes that might be used to improve salt tolerance in sorghum. The transcriptional profiles presented here provide further understanding of the salt-tolerance mechanism in sorghum.