Sustainable wheat production is the ultimate goal across countries as it is a staple food crop. Since brown (leaf) rust disease of common wheat (Triticum aestivum L.) spreads aerially to faraway lands and their urediniospores have a rapid production rate, it results in 10-50% of the total yield loss. With the change in climatic conditions, the decreased efficacy of existing resistant gene of leaf rust and increased virulence of pathogen is a potential threat towards managing the disease. Our study aims at revealing the probable involvement of cytosine methylation during the leaf rust pathogenesis. Cytosine methylation is a very significant biomarker which since last decade, has emerged in the regulation of gene expression across the entire genome in many plants and animals and is considered a paramount epigenetic mark among other epigenetic modifications. However, it is not thoroughly studies in wheat with its mechanism of action towards leaf rust still unclear and less explored. Here, we have used Ultrahigh Performance Liquid Chromatography coupled with Mass Spectrometry (UHPLC-MS) to precisely provide comparative quantification of total 2ˈ-deoxycytidine (dC) and 5-methyl 2ˈ-deoxycytidine (5-mdC) residues in DNA sample of wheat Near Isogenic Lines (NILs), HD2329 (seedling leaf rust susceptible, infection type +3) and HD2329+Lr24 (seedling leaf rust resistance, infection type 0-0). The infection was induced during two leaflet stage (~12 days after germination) with urediniospores of P. triticina pathotype 77-5 by mixing the inoculum with 0.75% Tween-20 solution. The leaf rust pathogenesis progression and the variation in the amount of dC and mdC with time were achieved by digesting the DNA with DNA Degradase enzyme which was then filtered and subjected to the UHPLC analysis. The percentage methylation at genomic level was then calculated to highlight the differential methylation pattern between the two NILs.

This study would help in understanding the crosstalk between the gene pool of wheat and cytosine methylation during the leaf rust disease rendering it as a potential molecular marker of wheat’s response during biotic stress. It might also help in building conceptual knowledge and combating the current virulence that has come to fore among the pathogens resulting in diminishing effects of existing resistant genes and understanding the mechanism of epigenetics during plant-pathogen interaction. Thus, summarizing its potential role in improving breeding programs to produce more resilient wheat varieties.