Unraveling the impact of abiotic stress on conserved microRNA expression and their target genes in Stevia rebaudiana.

Production of stevioside and rebaudioside in Stevia rebaudiana is greatly affected due to extreme environmental conditions. MicroRNAs are known to play an important role in post-transcriptional gene regulation. Here, the aim was to study the effect of abiotic stresses on the Stevia plantlets and then to identify and validate the expression of the conserved microRNAs and their targets under abiotic stress conditions. The effect of dehydration, salinity and cold stress treatment on 7-week-old Stevia plantlets was analyzed. Plant growth, relative water content, malondialdehyde content and antioxidant activity were greatly affected under stress treatment. In the present investigation, amongst the various abiotic stresses studied, 9% PEG treatment greatly affected the Stevia plantlets. To identify the microRNAs, BLAST analysis was performed. A homology search of known miRNAs from the PMRD database against non-redundant Stevia genomic sequences resulted in the prediction of 37 conserved miRNAs and their targets were identified using the psRNATarget server. All the predicted miRNAs had lengths of 20, 21, 22, 23, 24, and 25 nucleotides, respectively. The identified potential conserved miRNAs belong to 34 distinct miRNA families. The highest potential miRNAs are represented by miR169 family followed by miR156, miR172, and miR396 families. Promoter analysis of miRNA-targets genes revealed the presence of numerous cis-acting regulatory elements involved in hormonal and stress-response mechanisms. Further, expression analysis revealed an inverse correlation between the selected identified miRNAs and their targets under abiotic stress treatments. Identifying stress-responsive miRNAs and their targets will help us understand the molecular mechanisms of stress tolerance in Stevia.

Supplementary information: The online version contains supplementary material available at 10.1007/s12298-024-01527-5.