Genome-wide identification of DCL, AGO, and RDR gene families in wheat ( Triticum aestivum L.) and their expression analysis in response to heat stress

Key components of the RNA interference (RNAi) pathway include the Dicer-like (DCL), Argonaute (AGO), and RNA-dependent RNA polymerase ( RDR ) gene families. While these components have been studied in various plant species, their functional validation in wheat remains unexplored particularly under heat stress. In this study, a comprehensive genome-wide analysis to identify, and characterize DCL, AGO , and RDR genes in wheat and their expression patterns was carried out. Using phylogenetic analysis with orthologous genes from Arabidopsis and rice, we identified a total of 82 AGO , 31 DCL , and 31 RDR genes distributed across the 21 chromosomes of wheat. To understand the regulatory network, a network analysis of miRNAs that target RNA-silencing genes was performed. Our analysis revealed that 13 miRNAs target AGO genes, 8 miRNAs target DCL genes, and 10 miRNAs target RDR genes at different sites, respectively. Additionally, promoter analysis of the RNA-silencing genes was done and identified the presence of 132 cis -elements responsive to stress and phytohormones. To examine their expression patterns, we performed RNA-seq analysis in the flag leaf samples of wheat exposed to both normal and heat stress conditions. To understand the regulation of RNA silencing, we experimentally analysed the transcriptional changes in response to gradient heat stress treatments. Our results showed constitutive expression of the AGO1, AGO9 , and DCL2 gene families, indicating their importance in the overall biological processes of wheat. Notably, RDR1 , known to be involved in small interfering RNA (siRNA) biogenesis, exhibited higher expression levels in wheat leaf tissues. These findings suggest that these genes may play a role in responses to stress in wheat, highlighting their significance in adapting to environmental challenges. Overall, our study provides additional knowledge to understand the mechanisms underlying heat stress responses and emphasizes the essential roles of these gene families in wheat.