Genome-Wide Identification and Characterization of NODULE-INCEPTION-Like Protein (NLP) Family Genes in Brassica napus

NODULE-INCEPTION-like proteins (NLPs) are conserved, plant-specific transcription factors that play crucial roles in responses to nitrogen deficiency. However, the evolutionary relationships and characteristics of family genes in are unclear. In this study, we identified 31 genes in , including 16 genes located in the A subgenome and 15 in the C subgenome. Subcellular localization predictions indicated that most BnaNLP proteins are localized to the nucleus. Phylogenetic analysis suggested that the gene family could be divided into three groups and that at least three ancient copies of genes existed in the ancestor of both monocots and dicots prior to their divergence. The ancestor of group III genes may have experienced duplication more than once in the Brassicaceae species. Three-dimensional structural analysis suggested that 14 amino acids in BnaNLP7-1 protein are involved in DNA binding, whereas no binding sites were identified in the two RWP-RK and PB1 domains conserved in BnaNLP proteins. Expression profile analysis indicated that genes are expressed in most organs but tend to be highly expressed in a single organ. For example, subfamily members are primarily expressed in roots, while the four subfamily members are highly expressed in leaves. genes also showed different expression patterns in response to nitrogen-deficient conditions. Under nitrogen deficiency, all members of the subfamilies were upregulated, all subfamily members were downregulated, and subfamily members showed various expression patterns in different organs. These results provide a comprehensive evolutionary history of genes in , and insight into the biological functions of genes in response to nitrogen deficiency.