Genome-wide identification and characterization of NPF family reveals NtNPF6.13 involving in salt stress in Nicotiana tabacum

Proteins of the Nitrate Transporter 1/Peptide Transporter (NPF) family transport a diverse variety of substrates, such as nitrate, peptides, hormones and chloride. In this study, a systematic analysis of the tobacco (Nicotiana tabacum) NPF family was performed in the cultivated 'K326'. In total, 143 NtNPF genes were identified and phylogenetically classified into eight subfamilies, NPF1 to NPF8, based on the classification of NPF families in other plant species. The chromosomal locations and structures of the NtNPF genes were analyzed. The expression profiles of NtNPF genes under NaCl stress were analyzed to screen the possible NPF genes involving in chloride regulation in tobacco. Most NtNPF6 genes responded to salt stress in the roots and leaves. The expression of NtNPF6.13 was significantly down-regulated after salt stress for 12h. The chloride content was reduced in the roots of ntnpf6.13 mutant. These findings support the participation of NtNPF6.13 in chloride uptake. Several other NtNPF genes that play potential roles in chloride metabolism of tobacco require further study.