Abstract:

To explore the biological characteristics and expression patterns of NHX gene family in quinoa（Chenopodium quinoa Willd.） under salt stress is aimed to provide theoretical basis for the study of quinoa salt tolerance. Based on the protein sequence of quinoa containing Na⁺/H⁺ exchange domain, its gene structure, protein motif, physicochemical properties and transcriptional expression under salt stress were analyzed. The results showed that the quinoa genome contained 46 members of the NHXs gene family, and the amino acid length, molecular mass, isoelectric point, hydrophilicity and instability index were between 109-1 820 aa，11 472.74-204 381.38 Da，5.00-9.27，-0.226-1.112 and 21.71-50.73，respectively. The phylogenetic tree analysis can be divided into 5 subgroups, and the NHXs genes with similar positions in the phylogenetic tree had similar structures. The NHXs proteins in the same subgroup had similar motif structures and were orthologous to Arabidopsis, wheat and maize, and most of them were localized in cell membranes and vacuoles. Through the analysis of quinoa transcriptome data under salt stress, with the increase of salt stress time, the transcription levels of 26 NHXs genes increased，9 decreased, and 11 did not change significantly. In addition，35 NHXs genes expressions induced by salt stress were mainly involved in ions, cellular homeostasis and ion transmembrane transport processes through GO annotation. Diversity of NHXs gene structure and protein motifs, it is speculated that different subgroups of NHXs were involved in different response processes under salt stress. In addition, the different expression patterns under salt stress also suggest an important role in the process of salt stress.

Key words: quinoa, NHX gene family, gene structure, motif, physicochemical property, salt stress, expression pattern