Study of miRNAs involved in drought and salt stress stresses and ontology of target genes in Brassica species

Abiotic stresses such as drought and salinity significantly affect plant growth and performance. Plants use strategies to adapt and tolerate drought and salt stress that may threaten their survival during their life cycle, one of which is miRNA-mediated post-transcriptional regulation.

In the current research, miRNAs that showed significant expression during salt and drought stress were selected by checking the references to investigate this phenomenon in rapeseed plants. The phylogenetic tree was constructed to analyze and compare the evolutionary relationships and conservation of MicroRNA effective in drought and salinity stress in Brassica napus, Brassica rapa, and Brassica oleracea species. Target genes for selected miRNAs were identified using psRNATarget online software. Categorization and gene ontology of target genes and identification of biological pathways were accomplished; also, proteins were classified based on molecular function and biological processes. The Protein-protein interaction was analyzed to comprehensively interpret the relationships between the target genes. In the present study, 225 target genes for miRNAs were identified.

After examining the protein interaction network, it was found that there were the most interactions between ribosomal, proteasome subunits and the ubiquitin-proteasome system. This result determined that drought and salinity stress leads to the activation of various biological systems and pathways and changes in gene expression along with the activation of the protein synthesis machine and alterations in protein content. By activating post-transcriptional gene regulation (PTGR) and post-translational modifications (PTMs), the plant regulates the abundance, activities, intracellular distribution, and transport of regulatory proteins involved in various growth processes as well as stress response. 

The results of this study will lead to a broader perspective regarding stress and its effect on the pathways involved in cellular processes and will reveal the wide dimensions of the stress response.