Abstract
Obtaining information on the genetic diversity and population structure of germplasm facilitates its use in wheat breeding programs. Recently, with the development of next-generation sequencing technology, genotyping-by-sequencing (GBS) has been used as a high-throughput and cost-effective molecular tool for examination of the genetic diversity of wheat breeding lines. In this study, GBS was used to characterize a population of 180 accessions of common wheat originating from Asia and Europe between the latitudes 30° and 45°N. In total, 24,767 high-quality single-nucleotide polymorphism (SNP) markers were used for analysis of genetic diversity and population structure. The B genome contained the highest number of SNPs, followed by the A and D genomes. The polymorphism information content was in the range of 0.1 to 0.4, with a mean of 0.26. The distribution of SNPs markers on the 21 chromosomes ranged from 243 on chromosome 4D to 2,337 on chromosome 3B. Structure and cluster analyses divided the panel of accessions into two subgroups (G1 and G2). G1 principally consisted of European and partial Asian accessions, and G2 comprised mainly accessions from the Middle East and partial Asia. Molecular analysis of variance showed that the genetic variation was greater within groups (99%) than between groups (1%). Comparison of the two subgroups indicated that G1 and G2 contained a high level of genetic diversity. The genetic diversity of G2 was slightly higher as indicated by the observed heterozygosity (Ho) = 0.23, and unbiased diversity index (uh) = 0.34. The present results will not only help breeders to understand the genetic diversity of wheat germplasm on the Eurasian continent between the latitudes of 30° and 45°N, but also provide valuable information for wheat genetic improvement through introgression of novel genetic variation in this region.
Highlights
Wheat (Triticum aestivum L.) is an important staple food crop for more than one-third of the world’s population and provides about 20% of calories consumed by humans (Marcussen et al, 2014; Bhatta et al, 2017)
The highest number of single-nucleotide polymorphism (SNP) were identified in the B genome (12,028), followed by the A genome (9,741), and the D genome had the lowest number of polymorphic markers with 2,998 (Figure 1A, Supplementary Table 3)
In the A genome, chromosome 2A had the highest number of SNPs (1,761), and chromosome 6A harbored the lowest number (1,154); in the B genome, the highest and lowest number of SNPs were detected on chromosomes 3B and 4B (2,337 and 1,130, respectively); in the D genome, chromosome 2D had the highest number of SNPs (597), and chromosome 4D harbored the lowest number (243) (Figure 1B, Supplementary Table 3)
Summary
Wheat (Triticum aestivum L.) is an important staple food crop for more than one-third of the world’s population and provides about 20% of calories consumed by humans (Marcussen et al, 2014; Bhatta et al, 2017). As a result of ongoing population growth and climate change, it has been estimated that wheat production must increase by 50% by 2050 (Grassini et al, 2013; Ray et al, 2013; Marcussen et al, 2014). It seems that wheat production cannot meet demand. Domestication and strong selection pressure by humans, and the use of modern breeding techniques, have increasingly narrowed the gene pool of wheat (Tanksley and McCouch, 1997; Haudry et al, 2007). It is essential to enrich wheat germplasm resources by introducing favorable mutations into the cultivated gene pool (Tanksley and McCouch, 1997; Haudry et al, 2007; Zhang et al, 2017)
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