Genome-wide investigation of regulatory roles of lncRNAs in response to heat and drought stress in Brassica juncea (Indian mustard)

Long non-coding RNAs are in general described as transcripts >200 nt and lacking potential to code for proteins. In the present study, 7613 putative lncRNAs were identified in Brassica juncea genome using in silico approaches. Of these, 1614 lncRNAs were found to be differentially expressed in response to heat and drought stress conditions. Further, we characterized these lncRNAs and performed functional annotation based on co-expression analysis strategy and pathways enrichment analysis. On these bases, the identified abiotic stress-responsive lncRNAs were found to be associated with important pathways including both enzymatic and non-enzymatic antioxidants such as glutathione metabolism, phenylpropanoid biosynthesis, cysteine metabolism, etc. Moreover, lncRNAs were also found to co-express with transcription factors associated with abiotic stress response. Finally, those lncRNAs were identified that could act as putative targets and endogenous target mimics of miRNAs involved in response to heat and drought. Further investigation could be carried out for select lncRNA candidates like those for which quantitative polymerase chain reaction analysis was performed in this study or for those which were estimated as promising modulators of stress response based on miRNA-lncRNA interaction studies. Overall, our study highlights the potential role of lncRNAs in B. juncea in response to both heat and drought stress and can help elucidate the mechanism of tolerance to these abiotic stress conditions in the oil seed crop.