Drought Tolerance Mechanisms in Sesame Genotypes

Sesame (Sesamum indicum) is a vital oilseed crop cultivated mainly under rainfed conditions in arid and semi-arid regions. Drought events during critical growth stages, notably flowering and seed filling, can severely curtail yield. Tolerant genotypes employ a multifaceted strategy that integrates morphological, physiological and molecular adjustments. Key features include a deep and functional root system capable of sustaining water uptake under soil moisture deficit, coupled with osmotic adjustment through the accumulation of compatible solutes such as proline and soluble sugars. An enhanced antioxidant defence network mitigates cellular damage by scavenging reactive oxygen species. At the molecular level, drought-responsive transcription factors regulate pathways for hormone signalling—particularly abscisic acid and ethylene—and activate genes involved in osmoprotectant biosynthesis, photosynthetic maintenance and cell-wall stability. Advances in genomics have identified quantitative trait loci and candidate alleles underlying these traits, offering targets for marker-assisted selection. By bridging field-level performance with gene-level understanding, researchers aim to develop varieties that combine high oil yield with robust drought resilience, contributing to food security and sustainable agriculture in water-limited environments.

Research from Nature Portfolio

Investigations of two contrasting sesame genotypes under progressive drought have provided an integrated view of tolerance mechanisms. The drought-tolerant line maintained root integrity and water transport to aerial tissues, thereby preserving photosynthetic capacity. Biochemical assays demonstrated elevated levels of osmoprotectants and strong activity of antioxidant enzymes such as peroxidases in tolerant roots. Temporal transcriptome profiling revealed early and sustained induction of genes encoding antioxidant proteins, osmoprotectant biosynthetic enzymes and components of abscisic acid and ethylene signalling pathways. Unique differentially expressed loci included peroxidases, heat-shock proteins and ethylene-responsive transcription regulators that together orchestrate reactive oxygen species scavenging and cell-wall reinforcement. In total, more than sixty candidate genes were pinpointed for breeding programmes aimed at enhancing drought endurance in sesame.

Drought Tolerance Mechanisms in Sesame Genotypes publication trend

The graph below shows the total number of articles in drought tolerance mechanisms in sesame genotypes across all publications each year (not limited to Nature Index journals).

Technical terms

Osmoprotectants: Small compatible solutes, such as proline and soluble sugars, that stabilise cellular osmotic balance under water deficit.

Antioxidant enzymes: Proteins like superoxide dismutase and peroxidase that detoxify reactive oxygen species generated during stress.

Transcription factors: Regulatory proteins (e.g. ERF, NAC) that bind DNA to control expression of drought-responsive genes.

Quantitative trait locus (QTL): A genomic region statistically associated with variation in a complex trait such as drought tolerance.

Genome-wide association study (GWAS): An analytical approach linking genetic polymorphisms across the entire genome to phenotypic variation in a population.

References

1. Transcriptomic, biochemical and physio-anatomical investigations shed more light on responses to drought stress in two contrasting sesame genotypes. Scientific Reports (2017).
2. Comparative analysis of drought stress-induced physiological and transcriptional changes of two black sesame cultivars during anthesis. Frontiers in Plant Science (2023).
3. Identifying Traits Associated With Terminal Drought Tolerance in Sesame (Sesamum indicum L.) Genotypes. Frontiers in Plant Science (2021).
4. GWAS Uncovers Differential Genetic Bases for Drought and Salt Tolerances in Sesame at the Germination Stage. Genes (2018).