【Objective】The study was carried out to explore the whole genome characteristics and expression patterns of NLP transcription factors in apple, and further understand its structural characteristics and mechanism.【Method】Based on the local BLAST database and Pfam database, the members of NLP transcription factor family in the whole genome of apple were identified by using two query strategies with blastp and hmmsearch. Through strict filtration and confirmation, the results were used for further analysis, and analysis mainly divides into three parts, including NLP proteins analysis, analysis of NLP genes and NLP expression analysis in apple. Programs or softwares, such as ProtParam, Clustal Omega, MEGA7, MEME 5.0.2, SOPMA, Phyre 2, WoLF PSORT and STRING, were used for protein analysis, online tools included MG2C, GSDS2.0, PlantCARE, psRNATarget, were used for gene analysis, and the expression of MdNLP gene was quantitatively detected by qRT-PCR.【Result】6 NLP members were identified from apple protein databases, which were classified into three categories by phylogenetic analysis: I, II and III. The protein secondary structure was dominated by random coil, followed by alpha-helix, and the smallest proportion was beta-turn. The prediction of subcellular localization was located in the nucleus, which was consistent with the characteristics of transcription factors. Chromosome localization showed that five genes (except MDP0000584547) were located on four chromosomes. Promoter analysis revealed a large number of cis-acting elements related to hormone and stress response, suggesting that MdNLP genes might be involved in the regulation of hormone and stress signals. In addition, a nitrogen-responsive GCN4 element was also identified, further indicating that such transcription factors were closely related to nitrogen. By quantitative detection, the pattern which NLP family had high expression in stem and leaf of apple was revealed. And the expression analysis results also confirmed that MdNLP genes responded to nitrogen starvation and drought stress, and so on.【Conclusion】Through the apple genome analysis, 6 NLP transcription factors were found; the analysis of structure and conserved domain of protein for 6 gene suggested that there had a very high similarity and conservation between them, at the same time, they were different in a way; the associated protein network of NLP family in Arabidopsis thaliana were used for MdNLPs, MDP0000132856, which had the highest homology with AtNLP7, might also have complicated features and functions.
