Genome-Wide Identification and Expression Analysis of the Cation Diffusion Facilitator Gene Family in Turnip Under Diverse Metal Ion Stresses

Abstract

The cation diffusion facilitator (CDF) family is one of the gene families involved in metal ion uptake and transport in plants, but the understanding of the definite roles and mechanisms of most CDF genes remain limited. In the present study, we identified 18 candidate CDF genes from the turnip genome and named them BrrMTP1.1–BrrMTP12. Then, we performed a comparative genomic analysis on the phylogenetic relationships, gene structures and chromosome distributions, conserved domains, and motifs of turnip CDFs. The constructed phylogenetic tree indicated that the BrrMTPs were divided into seven groups (groups 1, 5, 6, 7, 8, 9, and 12) and formed three major clusters (Zn-CDFs, Fe/Zn-CDFs, and Mn-CDFs). Moreover, the structural characteristics of the BrrMTP members in the same group were similar but varied among groups. To investigate the potential roles of BrrMTPs in turnip, we conducted an expression analysis on all BrrMTP genes under Mg, Zn, Cu, Mn, Fe, Co, Na, and Cd stresses. Results showed that the expression levels of all BrrMTP members were induced by at least one metal ion, indicating that these genes may be related to the tolerance or transport of those metal ions. Based on the roles of different metal ions for plants, we hypothesized that BrrMTP genes are possibly involved in heavy metal accumulation and tolerance to salt stress apart from their roles in the maintenance of mineral nutrient homeostasis in turnip. These findings are helpful to understand the roles of MTPs in plants and provide preliminary information for the study of the functions of BrrMTP genes.

Genome-wide identification and characterization of the metal tolerance protein (MTP) family in grape (Vitis vinifera L.)

“…The main role of MTP genes is resistance to metals, and the expression analysis showed that these genes have different expressions at different stages of growth and development. Expression profiles of BrrMTP genes in roots and leaves tissues of Turnip demonstrated different expression patterns that are similar to this experiment (Li et al 2018).…”

“…The potential role of BrrMTP family of turnips was analyzed in the presence of different metal ions and the specific gene differentially expressed under different metal treatments. Some genes upregulated or downregulated with each metal ion and gene in the same cluster did not show similar expression changes to the same metal treatments (Li et al 2018). Overexpression of cucumber MTP9 in A. thaliana caused a significant tolerance to cadmium and surplus manganese, and transfer of the CsMTP9 gene to yeast resulted in detoxification of high concentrations of Cd 2+ and Mn 2+ (Migocka et al 2015).…”

Genome-Wide Identification of Metal Tolerance Protein Genes in Populus trichocarpa and Their Roles in Response to Various Heavy Metal Stresses

“…In addition, it is notable that unlike other PtrMTP members, PtrMTP12 had the largest protein size (869 amino acids), MW (97.50 kD) and TMD number (12 TMDs) ( Table 1). This result was consistent with the characteristics of other plants MTP12 [23,25,26], indicating the distinctive biological functions and evolutionary processes of MTP12. Moreover, ZT_dimer has been recognized as the dimerization region of metal ion transporters, through which the homodimers or heterodimers of MTPs can form [31].…”

“…For instance, excess Cu, which is not a potential substrate for the MTP family, could induce the transcription levels of PtrMTP genes (Figure 7, Table 5). Similar findings were also made in sweet orange and turnip [24,25]. Other than Mn, the expression of the Mn-CDFs, PtrMTP9 and PtrMTP10.3 were sharply upregulated by excess Fe and Zn, respectively (Figure 7, Table 5).…”

“…Compared with that of previous report, three new MTP genesn were found in P. trichocarpa [20]. The number of MTPs in P. trichocarpa was only second to N. tabacum among the plant species in which the MTPs have been identified [5,8,[22][23][24][25][26][27][28]. However, despite the large number of PtrMTPs, the homolog of AtMTP2 in P. trichocarpa was not detected.…”