Comparative transcriptome profiling of contrasting finger millet (Eleusine coracana (L.) Gaertn) genotypes under heat stress

Background: Eleusine coracana (L.) Gaertn is a crucial C 4 species renowned for its stress robustness and nutritional significance. Because of its adaptability traits, finger millet (ragi) is a storehouse of critical genomic resources for crop improvement. However, more knowledge about this crop's molecular responses to heat stress must be gained. Methods and Results: In the present study, a comparative RNA sequencing analysis was done in the leaf tissue of the finger millet between the heat-sensitive (KJNS-46) and heat-tolerant (PES-110) cultivars of Ragi in response to high temperatures. On average, each sample generated about 24 million reads. Interestingly, a comparison of transcriptomic profiling identified 684 transcripts which were significantly differentially expressed genes (DEGs) examined between the heat-stressed samples of both genotypes. The heat-induced change in the transcriptome was confirmed by qRT-PCR using a set of randomly selected genes. Pathway analysis and functional annotation analysis revealed the activation of various genes involved in response to stress, precisely heat, oxidation-reduction process, water deprivation, heat shock protein (HSP) and transcription factors, calcium, and kinase signaling. The basal regulatory genes, such as bZIP, were involved in response to heat stress, indicating that heat stress activates genes related to basal regulatory processes or housekeeping. A substantial percentage of the DEGs belonged to proteins of unknown functions (PUFs), i.e., uncharacterized. Conclusion: The finding highlights the importance of HSPs, candidate genes, and pathways that can confer tolerance towards heat stress in ragi. These results will provide valuable information to improve heat tolerance in heat-susceptible agronomically important varieties of ragi and other crop plants.