Genome-wide identification of the ZIP gene family in lettuce (Lactuca sativa L.) and expression analysis under different element stress

The ZIP protein (ZRT, the IRT-like protein) is an important metal transporter that transports Zn, Fe, and other divalent metal ions in plants. In this study, we identified 20 ZIP genes in lettuce (Lactuca sativa L.). We used bioinformatics methods and renamed them according to their E value in hmmsearch. We also analyzed their gene structure, chromosomal location, constructed a phylogenetic tree, conserved motifs, performed synonymous analysis and responses to abiotic stresses. The results show that these LsZIP genes have 3–11 exons and were distributed unequally on 8 of the 9 chromosomes in lettuce. Based on phylogenetic analyses, the LsZIP gene family can be divided into three subfamilies, and the LsZIP genes within the same subfamily shared similar gene structure. The LsZIP genes contain 12 Motifs, of which Motif1 to Motif8 are widely distributed in group Ⅰ. Furthermore, the LsZIP gene contains numerous hormones and anti-stress response elements. Real-time quantitative PCR demonstrated that most LsZIP genes is up-regulated under the elemental stress in this experiment, indicating that they are positively regulated. But different elemental stressors can induce the expression of LsZIP gene to varying degrees. The LsZIP genes also change in response to different elemental stresses. The present study serves as a basic foundation for future functional studies on the lettuce ZIP family.