Comparative Analysis of Root Transcriptome Profiles of Sesame (Sesamum indicumL.) in Response to Osmotic Stress

Sesame (Sesamum indicumL) is a high-value oilseed cash crop grown across different geographies. Although sesame is traditionally considered drought-tolerant, early seedling and vegetative stage plants are sensitive to drought, causing substantial yield losses. Roots are the sensors of water deficit and hence are determinants of drought stress-induced responses. Limited information is available about the molecular responses induced in sesame roots during osmotic stress. We performed RNA-sequencing to understand transcriptional changes in the roots of drought-tolerant (TEX-1) and drought-sensitive (VEN-1) sesame genotypes using Polyethylene glycol (PEG)-induced osmotic stress. The photosynthetic measurements and proline accumulation confirmed contrasting drought stress reactions between the two genotypes. A total of 1251 and 541 unique genes were differentially expressed in PEG-treated and untreated roots of TEX-1 and VEN-1 roots, respectively. Gene ontology (GO) function enrichment analysis revealed that the differentially expressed genes related to catalytic activity, ion binding, transferase activity, and cation binding activities were over-represented. Transcription-factor enrichment analysis showed that multiple members of WRKY, bZIP, MYB, and NAC families were over-represented in the roots of drought-tolerant genotype during osmatic stress. The study identified several genes involved in the primary metabolism, phenylpropanoid, and hormonal pathways induced in the roots of drought-tolerant genotype. The study provided a comparative transcriptome resource for understanding molecular responses underlying osmotic stress and identified target genes for enhancing abiotic stress tolerance in sesame.

Automated summary

This study investigated transcriptional changes in the roots of drought-tolerant and drought-sensitive sesame genotypes under osmotic stress induced by Polyethylene glycol (PEG), revealing contrasting reactions between the two genotypes. Gene ontology and transcription-factor enrichment analysis showed significant differences in genes related to catalytic activity and transferase activity among different genotypes.