Rhizosphere Microbiome Dynamics of BNI-Enriched Wheat Genotypes Across Contrasting Nitrogen Levels

Biological nitrification inhibitors (BNIs) assist in enhancing nitrogen availability in the wheat (Triticum aestivum L.) rhizosphere by suppressing nitrification in the rhizosphere through root-derived metabolites that may alter microbial populations associated with the nitrogen cycle and nitrogen-use efficiency. Plant roots interact with a variety of microbial communities in the rhizosphere, which is a significant hotspot for microbial diversity and activity. These microbial communities play an important role in the transformation and cycle of carbon and essential nutrients, including nitrogen and phosphorus, within the rhizosphere. Rhizospheric soil samples from three BNI-enriched genotypes, viz., BNI Munal, BNI Roelfs, and BNI Vorobey, along with their respective parental genotypes Munal, Roelfs, and Vorobey and three commercial cultivars, viz., DBW 187, DBW 303, and DBW 371, were evaluated in a pot experiment using 16S rRNA gene amplicon sequencing at four nitrogen levels (0%, 50%, 75%, and 100%) in order to study the population dynamics of the bacterial community. In the present study, the bacterial range related to the rhizosphere of the wheat plant was analyzed via PCR amplification, production of a library, and sequencing of 16S rDNA genes. The comparative analysis of bacterial abundance levels of different samples was carried out at phylum, class, order, family, genus, and species levels. Both host genotype and nitrogen availability had an impact on the organization of the bacterial community in the wheat rhizosphere, as evidenced by the differences in the relative abundance of key bacterial taxa with these factors. Diversity indices indicated differences in the relative abundance of bacterial taxa in the rhizosphere of the BNI-enriched genotypes, their parents, and the three commercial cultivars. The heatmap revealed differences in the relative abundance of bacterial taxa among rhizosphere soil samples, with Proteobacteria being one of the predominant phyla. The second ring of the Krona chart indicated that the bacterial population of the Nitrosomonadaceae family of the Proteobacteria phylum was found to be the most affected among BNI-enriched genotypes when nitrogen level was altered. This suggests that, when using 16S r RNA gene amplicon sequencing, the wheat genotype and nitrogen availability were associated with changes in bacterial taxa related to nitrogen cycling, but their functional effect remains to be confirmed. These findings have laid the groundwork for analyzing the impact of associated microbiota on future wheat production systems, particularly concerning nitrification.