Nitrogen is a critical factor in plant growth, development, and crop yield. NODULE-INCEPTION-like proteins (NLPs), which are plant-specific transcription factors, function as nitrate sensors and play a vital role in the nitrogen response of plants. However, the genome-wide identification of the NLP gene family, the elucidation of the underlying molecular mechanism governing nitrogen response, and haplotype mining remain elusive in millet. In this study, we identified seven members of the NLP gene family in the millet genome and systematically analyzed their physicochemical properties. Evolutionary tree analysis indicated that SiNLP members can be classified into three subgroups, with NLP members from the same species preferentially grouped together within each subgroup. Analysis of gene structure characteristics revealed that all SiNLP members contained 10 conserved motifs, as well as the RWP-RK and PB1 domains, indicating that these motifs and domains have been relatively conserved throughout evolution. Additionally, we identified a significant abundance of response elements related to hormones, stress, growth, and development within the promoter regions of SiNLP members, suggesting that these members are involved in regulating diverse physiological processes in millet. Transcriptome data under low-nitrogen conditions showed significant differences in the expression profiles of SiNLP2 and SiNLP4 compared to the other members. RNA-seq and qRT-PCR results demonstrated that SiNLP2 significantly responds to low-nitrogen stress. Notably, we found that SiNLP2 is involved in nitrogen pathways by regulating the expression of the SiNAR2.1A, SiNAR2.1B, SiNRT1.1, and SiNR2 genes. More importantly, we identified an elite haplotype, Hap2, of SiNLP2, which is gradually being utilized in the breeding process. Our study established a foundation for a comprehensive understanding of the SiNLP gene family and provided gene resources for variety improvement and marker-assisted selection breeding.

The ABCB subfamily, a subset transporter of the ATP-binding cassette (ABC) superfamily, is vital for various plant life processes, especially in the transport of polar auxin and brassinosteroids. Although ABCB transporters have been characterized in diverse plant species, their specific functions in wheat remain largely unexplored. In this study, we identified 99 TaABCB members in wheat and categorized them into four groups based on their conserved domains and phylogenetic relationships. These members were found to be unevenly distributed across all 21 wheat chromosomes. We conducted a comprehensive genome-wide analysis encompassing gene structure, protein motifs, gene duplication events, collinearity, and cis-acting elements. Transcriptome analysis revealed that different TaABCB members displayed distinct expression patterns under phosphate starvation stress. Notably, we discovered that TaABCB7 might play a role in regulating wheat’s phosphate starvation. Crucially, we pinpointed an elite haplotype, H001, of the candidate gene TaABCB7, which has been progressively selected and employed in wheat breeding improvement programs. Overall, this study enhances our comprehensive understanding of TaABCB members and offers a potential gene resource for molecular marker-assisted selection breeding in wheat.

The ABCB subfamily, a subset transporter of the ATP-binding cassette (ABC) superfamily, is vital for various plant life processes, especially in the transport of polar auxin and brassinosteroids. Although ABCB transporters have been characterized in diverse plant species, their specific functions in wheat remain largely unexplored. In this study, we identified 99 TaABCB members in wheat and categorized them into four groups based on their conserved domains and phylogenetic relationships. These members were found to be unevenly distributed across all 21 wheat chromosomes. We conducted a comprehensive genome-wide analysis encompassing gene structure, protein motifs, gene duplication events, collinearity, and cis-acting elements. Transcriptome analysis revealed that different TaABCB members displayed distinct expression patterns under phosphate starvation stress. Notably, we discovered that TaABCB7 might play a role in regulating wheat's phosphate starvation. Crucially, we pinpointed an elite haplotype, H001, of the candidate gene TaABCB7, which has been progressively selected and employed in wheat breeding improvement programs. Overall, this study enhances our comprehensive understanding of TaABCB members and offers a potential gene resource for molecular marker-assisted selection breeding in wheat.