Phenotypic characterization of sorghum seedlings and expression patterns of SNAC1 and DREB1A genes under water-stress: an insight towards developing resilient cultivars

Sorghum is an important cereal in many parts of the world, but water stress is a major constraint to its yield. In response to water stress, plants can modify gene expression, leading to a variety of changes in biochemical and physiological pathways. In the present study, 32 accessions of sorghum were screened for drought tolerance at the seedling stage based on morphometric traits. After 14 days of water stress, the most-tolerant (NGB01435) and susceptible (AKZ-NrSOR1013) accessions were assessed for drought-related gene expression research. The result of the morphometric attributes showed variation in seedling growth among the accessions. Also, significant correlations exist among the evaluated attributes, and the clustering pattern revealed genetic diversity in the accessions. The analysis of Ct values across the samples revealed differential expression of the reference gene (ELF4α) and the target genes (SNAC1 and DREB1A). SNAC1 is a stress-responsive NAC superfamily transcription factor, while DREB1A is a dehydration-responsive element binding protein 1 (DREB1)/C-repeat-binding factor (CBF), both of which are involved in stress regulation in plants. Both target genes had lower expression under stress in the tolerant accession (NGB01435) and were upregulated in the susceptible accession (AKZ-NrSOR1013). This study concluded that accessions respond differentially to water stress in terms of growth and development; the downregulation of both SNAC1 and DREB1A is critical to the mechanism involved in the water stress modulation to confer resistance in sorghum seedlings under water deficit conditions.