Phylogenetic, Structural, and Evolutionary Insights into Pepper NBS-LRR Resistance Genes

The comprehensive analysis of NBS-LRR resistance genes in the pepper (<i>Capsicum annuum</i> L.) genome reveals their structural diversity, evolutionary history, and functional importance in plant immunity. A total of 252 NBS-LRR genes were identified, distributed unevenly across all chromosomes, with 54% forming 47 gene clusters. These clusters, driven by tandem duplications and genomic rearrangements, underscore the dynamic evolution of resistance genes. Phylogenetic analysis demonstrated the dominance of the nTNL subfamily over the TNL subfamily, reflecting lineage-specific adaptations and evolutionary pressures. Structural analyses identified six conserved motifs (P-loop, RNBS-A, kinase-2, RNBS-B, RNBS-C, and GLPL) essential for ATP/GTP binding and resistance signaling. Subfamily-specific differences in motif composition and sequence similarity highlight their functional divergence and specialization. Comparative analyses across species further revealed a greater prevalence of nTNL genes in angiosperms, with significant losses of TNL genes in monocots. This study enhances our understanding of the evolution and diversification of plant-resistance genes and provides a foundation for developing disease-resistant crops through targeted breeding strategies.