Molecular and phylogenetic characterization of the homoeologous EPSP Synthase genes of allohexaploid wheat, Triticum aestivum (L.). (December 2015)

• Record Type: Journal Article
• Authors: Aramrak, Attawan; Kidwell, Kimberlee; Steber, Camille; Burke, Ian
• Is Part Of: BMC genomics. Volume 16:Number 1(2015)
• Page Start: 1
• Page End: 14
• Publication Date: 2015-12
• Subjects: Cloning -- EPSP synthase -- Glyphosate -- Polyploid -- TaEPSPS-4A1 -- TaEPSPS-7A1 -- TaEPSPS-7D1 -- Triticeae evolution -- Triticum aestivum -- Wheat; Genomes -- Periodicals; Gene mapping -- Periodicals; Genomics -- Periodicals; Base Sequence -- Periodicals; Chromosome Mapping -- Periodicals; Genetic Techniques -- Periodicals; Sequence Analysis, DNA -- Periodicals; 572.8605
• DOI: 10.1186/s12864-015-2084-1
• Languages: English
• ISSNs: 1471-2164

Abstract

Abstract Background 5-Enolpyruvylshikimate-3-phosphate synthase (EPSPS) is the sixth and penultimate enzyme in the shikimate biosynthesis pathway, and is the target of the herbicide glyphosate. TheEPSPS genes of allohexaploid wheat (Triticum aestivum, AABBDD) have not been well characterized. Herein, the three homoeologous copies of the allohexaploid wheatEPSPS gene were cloned and characterized. Methods Genomic and coding DNA sequences ofEPSPS from the three related genomes of allohexaploid wheat were isolated using PCR and inverse PCR approaches from soft white spring "Louise'. Development of genome-specific primers allowed the mapping and expression analysis ofTaEPSPS-7A1, TaEPSPS-7D1, andTaEPSPS-4A1 on chromosomes 7A, 7D, and 4A, respectively. Sequence alignments of cDNA sequences from wheat and wheat relatives served as a basis for phylogenetic analysis. Results The three genomic copies of wheatEPSPS differed by insertion/deletion and single nucleotide polymorphisms (SNPs), largely in intron sequences. RT-PCR analysis and cDNA cloning revealed that EPSPS is expressed from all three genomic copies. However, TaEPSPS-4A1 is expressed at much lower levels thanTaEPSPS-7A1 andTaEPSPS-7D1 in wheat seedlings. Phylogenetic analysis of 1190-bp cDNA clones from wheat and wheat relatives revealed that: 1)TaEPSPS-7A1 is most similar toEPSPS from the tetraploid AB genome donor, T. turgidum (99.7 % identity); 2)TaEPSPS-7D1 most resemblesEPSPS from the diploid D genome donor, Aegilops tauschii (100 % identity); and 3)TaEPSPS-4A1 resemblesEPSPS from the diploid B genome relative, Ae. speltoides (97.7 % identity). Thus, EPSPS sequences in allohexaploid wheat are preserved from the most two recent ancestors. The wheatEPSPS genes are more closely related toLolium multiflorum andBrachypodium distachyon than toOryza sativa (rice). Conclusions The three relatedEPSPS homoeologues of wheat exhibited conservation of the exon/intron structure and of coding region sequence, but contained significant sequence variation within intron regions. The genome-specific primers developed will enable future characterization of natural and induced variation inEPSPS sequence and expression. This can be useful in investigating new causes of glyphosate herbicide resistance.