Genome-Wide Identification of NBS-LRR Family in Three Nicotiana Genomes and Their Expression During Disease Resistance

<b>Background:</b> The NBS-LRR gene family plays a critical role in plant disease resistance and is considered a key determinant of plant immune responses. Research on the NBS-LRR gene family has grown rapidly, with significant progress driven by advances of molecular biology techniques. However, to date, there has been no systematic identification of NBS-LRR genes in <i>Nicotiana</i> species. <b>Methods</b>: In this study, we systematically characterized the NBS gene families in three <i>Nicotiana</i> genomes, investigated the evolution and environmental selection during the species formation, and explored the key NBS genes involved in disease resistance. <b>Results</b>: Results showed that 1226 NBS genes are present across the three <i>Nicotiana</i> genomes, and 76.62% of the members in <i>Nicotiana tabacum</i> could be traced back to their parental genomes. In addition, whole-genome duplication was found to contribute significantly to the expansion of NBS gene families. In addition, many NBS genes associated with disease resistance were identified, including one multi-disease resistance gene. <b>Conclusions</b>: This study provides new insights into the formation of NBS gene families in <i>Nicotiana</i> and offers new clues for understanding plant immunity.