Abstract
BackgroundThe trihelix gene family is a plant-specific transcription factor family that plays important roles in plant growth, development, and responses to abiotic stresses. However, to date, no systemic characterization of the trihelix genes has yet been conducted in wheat and its close relatives.ResultsWe identified a total of 94 trihelix genes in wheat, as well as 22 trihelix genes in Triticum urartu, 29 in Aegilops tauschii, and 31 in Brachypodium distachyon. We analyzed the chromosomal locations and orthology relations of the identified trihelix genes, and no trihelix gene was found to be located on chromosome 7A, 7B, or 7D of wheat, thereby reflecting the uneven distributions of wheat trihelix genes. Phylogenetic analysis indicated that the 186 identified trihelix proteins in wheat, rice, B. distachyon, and Arabidopsis were clustered into five major clades. The trihelix genes belonging to the same clades usually shared similar motif compositions and exon/intron structural patterns. Five pairs of tandem duplication genes and three pairs of segmental duplication genes were identified in the wheat trihelix gene family, thereby validating the supposition that more intrachromosomal gene duplication events occur in the genome of wheat than in that of other grass species. The tissue-specific expression and differential expression profiling of the identified genes under cold and drought stresses were analyzed by using RNA-seq data. qRT-PCR was also used to confirm the expression profiles of ten selected wheat trihelix genes under multiple abiotic stresses, and we found that these genes mainly responded to salt and cold stresses.ConclusionsIn this study, we identified trihelix genes in wheat and its close relatives and found that gene duplication events are the main driving force for trihelix gene evolution in wheat. Our expression profiling analysis demonstrated that wheat trihelix genes responded to multiple abiotic stresses, especially salt and cold stresses. The results of our study built a basis for further investigation of the functions of wheat trihelix genes and provided candidate genes for stress-resistant wheat breeding programs.
Highlights
The trihelix gene family is a plant-specific transcription factor family that plays important roles in plant growth, development, and responses to abiotic stresses
To confirm the reliability of the above identification, 31 published rice trihelix genes were used to search their homologous genes in wheat on NCBI by BLAST, and we found that all published wheat proteins containing the trihelix domain were included
The wheat trihelix genes were named from TaGT-1 to TaGT-94 based on their positions on the chromosomes
Summary
The trihelix gene family is a plant-specific transcription factor family that plays important roles in plant growth, development, and responses to abiotic stresses. Transcription factors (TFs) are extensively involved in the processes of plant growth and development through binding to specific cis-elements to modulate the expressions of target genes [1]. The first identified trihelix gene GT-1 was found in Pisum sativum, and orthologous genes were subsequently cloned in tobacco and Arabidopsis [6,7,8,9]. Studies on Arabidopsis suggest that trihelix genes play multiple roles in diverse development processes. Arabidopsis ASIL1 targets GT-box-containing embryonic genes and represses the expression of embryonic seed maturation genes in vegetative tissues [10, 11]. GTL1 has been reported to be involved in regulating ploidy-dependent cell growth in the Arabidopsis trichome [13]
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