Molecular Diversity within a Mediterranean and European Panel of Tetraploid Wheat (T. turgidum subsp.) Landraces and Modern Germplasm Inferred Using a High-Density SNP Array

Abstract

High-density single-nucleotide polymorphism (SNP) molecular markers are widely used to assess the genetic variability of plant varieties and cultivars, which is nowadays recognized as an important source of well-adapted alleles for environmental stresses. In our study, the genetic diversity and population genetic structure of a collection of 265 accessions of eight tetraploid Triticumturgidum L. subspecies were investigated using 35,143 SNPs screened with a 35K Axiom® array. The neighbor-joining algorithm, discriminant analysis of principal components (DAPC), and the Bayesian model-based clustering algorithm implemented in STRUCTURE software revealed clusters in accordance with the taxonomic classification, reflecting the evolutionary history of the Triticum turgidum L. subspecies and the phylogenetic relationships among them. Based on these results, a clear picture of the population structure within a collection of tetraploid wheats is given herein. Moreover, the genetic potential of landraces and wild relatives for the research of specific traits of interest is highlighted. This research provides a great contribution to future phenotyping and crossing activities. In particular, the recombination efficiency and gene selection programs aimed at developing durum wheat composite cross populations that are adapted to Mediterranean conditions could be improved.

Phenotypic evolution in durum wheat (Triticum durum Desf.) based on SNPs, morphological traits, UPOV descriptors and kernel-related traits

“…The distribution of accessions in the clusters was in agreement with Roncallo et al. (2019) and Ganugi et al. (2021) .…”

“…(2018) , genotyping by SSR DAPC an ex situ durum wheat collection from Southern Italy, identified six groups and more than 84% of modern varieties (released from 1974 to 2007) clustered together while old and intermediate varieties dispersed into 5 of the 6 groups formed. Ganugi et al. (2021) , evaluating the genetic diversity of 265 tetraploid wheat accessions by 21,051 SNP markers, found a strong selection activity into Italian modern varieties gathered in the same cluster and highlighted genetic homogeneity.…”

Characterization of Triticum turgidum sspp. durum, turanicum, and polonicum grown in Central Italy in relation to technological and nutritional aspects

“…turanicum ) that has reached a high popularity because of its suggested positive effects on human health ( Bordoni et al., 2017 ; Spisni et al., 2020 ). In the wake of KAMUT ® brand wheat, any Khorasan wheat is acquiring importance because it is considered healthy ( Geisslitz and Scherf, 2021 ), with some accessions sold under registered names and others simply described as such, sold as semolina or processed foods, with a wide market, especially in Western Countries where they can be found even in the large-scale distribution.…”

“…Furthermore, both Polish and Khorasan wheats, being able to be grown organically and adaptable to different environments, represent attractive and alternative crops for the marginal areas of Mediterranean basin, which were no longer widely cultivated due to the low grain yields compared with modern wheat cultivars. However, traditional (mostly local) farmers have continued to grow them to use in low-input agriculture, and they are a source of genetic diversity ( Ganugi et al., 2021 ). Moreover, they are important for economic reasons, because heritage wheats respond to the demand of a specific niche of consumers, careful to the need of conserving cultural habits, often associated by people with the concept of a healthier lifestyle.…”

Development of a Next Generation SNP Genotyping Array for Wheat

“…The bread wheat genome already contains significant genetic variation and much work is being done to enhance the germplasm with novel alleles from wide crosses. The previous 35k Breeders array had previously been used with wheat wild relative material in a pre-breeding context (Kumar et al, 2020; Wright et al, 2023) and for elite durum wheat cultivars (Kabbaj et al, 2017; Ganugi et al, 2021; Shewry et al, 2023). The genotype calls generated on the TaNG v1.1 array across a diverse set of wheat relative material here (Supplementary File S4) illustrate that secondary and tertiary genepool material may also be genotyped alongside T. aestivum accessions.…”