Original Article
Exploring genetic diversity of wild and related tetraploid wheat species Triticum turgidum and Triticum timopheevii

https://doi.org/10.1016/j.jare.2022.08.020Get rights and content
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Highlights

  • Systematic evaluation of genetic diversity exists in wild and related tetraploid wheat wheat species T. turgidum and T. timopheevii.

  • Using genotypic datasets, we found duplicated accessions in T. timopheevii (∼65 %) and in T. turgidum (47 %).

  • We combined genotypic and phenotypic datasets to identify core set accessions to introduce novel genetic diversity in wheat breeding programs.

Abstract

Introduction

The domestication bottleneck has reduced genetic diversity in wheat, necessitating the use of wild relatives in breeding programs. Wild tetraploid wheat are widely used in the breeding programs but with morphological characters, it is difficult to distinguish these, resulting in misclassification/mislabeling or duplication of accessions in the Gene bank.

Objectives

The study aims to explore Genotyping by sequencing (GBS) to characterize wild and domesticated tetraploid wheat accessions to generate a core set of accessions to be used in the breeding program.

Methods

TASSEL-GBS pipeline was used for SNP discovery, fastStructure was used to determine the population structure and PowerCore was used to generate a core sets. Nucleotide diversity matrices of Nie’s and F-statistics (FST) index were used to determine the center of genetic diversity.

Results

We found 65 % and 47 % duplicated accessions in Triticum timopheevii and T. turgidum respectively. Genome-wide nucleotide diversity and FST scan uncovered a lower intra and higher inter-species differentiation. Distinct FST regions were identified in genomic regions belonging to domestication genes: non-brittle rachis (Btr1) and vernalization (VRN-1). Our results suggest that Israel, Jordan, Syria, and Lebanon as the hub of genetic diversity of wild emmer; Turkey, and Georgia for T. durum; and Iraq, Azerbaijan, and Armenia for the T. timopheevii. Identified core set accessions preserved more than 93 % of the available genetic diversity. Genome wide association study (GWAS) indicated the potential chromosomal segment for resistance to leaf rust in T. timopheevii.

Conclusion

The present study explored the potential of GBS technology in data reduction while maintaining the significant genetic diversity of the species. Wild germplasm showed more differentiation than domesticated accessions, indicating the availability of sufficient diversity for crop improvement. With reduced complexity, the core set preserves the genetic diversity of the gene bank collections and will aid in a more robust characterization of wild germplasm.

Keywords

Tetraploid wheat
Nei’s index
F-statistics: (FST)
Core collection
Triticum
Population structure
Genetic diversity
Genotyping by sequencing (GBS)
Sequencing
Phenotype
Genome wide association study (GWAS)

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Peer review under responsibility of Cairo University.