Genome-wide identification of the ATP-dependent zinc metalloprotease (FtsH) in Triticeae species reveals that TaFtsH-1 regulates cadmium tolerance in Triticum aestivum

Abstract

The ATP-dependent zinc metalloprotease (FtsH) protein gene family is essential for plant growth, development, and stress responses. Although FtsH genes have been identified in various plant species, the FtsH gene family in wheat (Triticum aestivum) remains unstudied. In this study, we identified 11 TaFtsH genes with uneven chromosomal distribution, significant variations in gene sequence length, and differing intron numbers among individual members. Additionally, these proteins exhibit similar physicochemical characteristics as well as secondary and tertiary structures. The FtsH genes can be classified into eight groups, each characterized by similar structures and conserved motifs. Intraspecific and interspecific comparisons further revealed extensive gene duplications within the TaFtsH gene family, indicating a closer relationship to maize. Analysis of cis-acting elements in the promoter regions of TaFtsH genes revealed developmental and stress-responsive elements in most of the genes. Expression pattern analysis showed that TaFtsH genes are expressed in all wheat tissues, though with varying patterns. TaFtsH genes displayed differential responses to CdCl2, ZnSO4, and MnSO4 stress treatments. Gene Ontology (GO) enrichment analysis indicated that TaFtsH genes are involved in protein hydrolysis. Barley stripe mosaic virus-induced gene silencing (BSMV-VIGS) technology confirmed the function of TaFtsH-1, indicating that silencing TaFtsH-1 enhances common wheat's resistance to cadmium (Cd) toxicity. In summary, this study offers an in-depth understanding of the FtsH gene family in wheat, establishing a solid basis for comprehending its functions, genetic mechanisms, and improving wheat's tolerance to heavy metal contamination.

Fig 1. Tertiary structures of TaFtsH proteins.

Fig 2. Multiple sequence comparison of the TaFtsH proteins.

Fig 3. Phylogenetic relationships, conserved motifs and gene structures of 11 TaFtsH genes.

(a) Phylogenetic tree; (b) Conserved motifs. Different colored frames represent different protein motifs; (c) Conserved domain; (d) Coding sequences (CDS) and upstream/downstream sequences are indicated by green frames, yellow frames, respectively.

Fig 4. Chromosomal locations analysis of the wheat FtsH genes.

Fig 5. Phylogenetic analysis of FtsH genes in Triticum aestivum, Arabidopsis thaliana and Zea mays.

The different shapes indicated various species. Triangle: Wheat; Star: Arabidopsis; Square: Maize. The different background colours indicated the different FtsH gene types.

Fig 6. Promoter cis-acting elements analysis of the wheat FtsH genes.

The different coloured boxes indicated different types of cis-acting elements. (a) Phylogenetic tree; (b) Promoter cis-acting elements.

Fig 7. Collinearity analysis of the FtsH genes.

(a) Collinearity analysis among TaFtsH genes in Triticum aestivum. Pairs of segmented duplicate genes are linked with different color lines; (b) Collinearity analysis of FtsH genes among Triticum aestivum, Arabidopsis thaliana, and Zea mays through comparative genome analyses. The blue lines represented the collinearity of FtsH gene pairs.

Fig 8. GO annotation analysis of the Triticum aestivum FtsH genes.

Green column represented the molecular function; Wathet blue column represented the cellular component; Orange column represented the biological process and dark blue column represented the number of TaFtsH genes.

Fig 9. Expression patterns analysis of TaFtsH genes in different tissues.

Fig 10. Expression levels analysis of TaFtsH genes in response to different stresses.

(a) 0.2 mM CdCl₂ treatment; (b) 0.2 mM ZnSO₄ treatment; (c) 3 mM MnSO₄ treatment. The colour gradient (orange/yellow/blue) represented the gene expression level (from high to low).

Fig 11. Function analysis of the TaFtsH-1 gene by BSMV-VIGS.

(a) Phenotypes of WT, BSMV: γ-injected plants and BSMV: TaFtsH-1-injected plants; (b) Rrelative expression; (c) Cd concentrations; (d) Leaf length; (e) Root length; (f) Leaf dry weight; (g) Root dry weight. Varied letters (a-e) indicated a significant difference (p < 0.05).