Insight into the genetic variability analysis and relationships among some <i>Aegilops</i> and <i>Triticum</i> species, as genome progenitors of bread wheat, using SCoT markers

<p>We assessed the molecular genetic diversity and relationships among some Aegilops and Triticum species using 15 start codon-targeted (SCoT) polymorphism markers. A total of 166 bands amplified, of which 164 (98.79%) were polymorphic. Analysis of molecular variance and inter-population differentiation (<i>Gst</i>) indicated high genetic variation within the studied populations. Our analyses revealed high genetic diversity in <i>T. boeoticum</i>, <i>Ae. cylindrica</i>, <i>T. durum</i> and <i>Ae. umbellulata</i>, low diversity in <i>Ae. crassa</i>, <i>Ae. caudata</i> and <i>Ae. speltoides</i>, and a close relationship among <i>Ae. tauschii</i>, <i>T. aestivum</i>, <i>T. durum</i>, <i>T. urartu</i>, and <i>T. boeoticum</i>. Cluster analysis indicated 180 individuals divided into 8 genome homogeneous clades and 11 sub-groups. <i>T. aestivum</i> and <i>T. durum</i> accessions were grouped together, and accessions with the C and U genomes were grouped into the same clade. Our results support the hypothesis that <i>T. urartu</i> and <i>Ae. tauschii</i> are two diploid ancestors of <i>T. aestivum</i>, and also that <i>Ae. caudata</i> and <i>Ae. umbellulata</i> are putative donors of C and U genomes for other <i>Aegilops</i> species that possess these genomes. Our results also revealed that the SCoT technique is informative and can be used to assess genetic relationships among wheat germplasm.</p

Screening wheat germplasm for seedling root architectural traits under contrasting water regimes: potential sources of variability for drought adaptation

<p>In this study, we selected 180 accessions from different wild relatives of wheat (<i>Aegilops</i>–<i>Triticum</i> species) and tested them in the presence of a tolerant and a sensitive control variety under well-watered and drought-stressed conditions. The results of analysis of variance for dry masses and all measured root traits showed that water regimes, accession and species main effects were highly significant. Drought stress significantly declined shoot dry mass (59.42%), root length (37.85%) and the total number of branch roots (36.25%), but increased the root-to-shoot ratio (75.00%), specific root length (64.19%) and root tissue density (29.46%). Principal component analysis for 182 individuals and 12 species groups identified two components that explained 75.67 and 82.39% of the total variation in dry mass and root traits under drought-stressed conditions, respectively. Taking together, our results identified 12 accessions with superior tolerance to drought stress. Remarkably, four species of wild relatives – <i>Ae. cylindrica</i> (DC genome), <i>Ae. neglecta</i> (UM genome), <i>Ae. speltoides</i> (B genome) and <i>Ae. tauschii</i> (D genome) – responded well to drought stress. The potential of these species could be used for molecular analysis such as marker assisted selection and gene mapping, ultimately aimed at breeding for root traits with improved adaptation to drought environments.</p

Molecular characterization of the wild relatives of wheat using CAAT-box derived polymorphism

<p>A molecular assessment of genetic diversity was performed on a set of 228 selected accessions belonging to the different <i>Aegilops</i> and <i>Triticum</i> species using CAAT-box derived polymorphism (CBDP) markers. Fifteen CBDP primers generated 141 polymorphic fragments with an average of 9.40 per primer. The average of polymorphic information content and resolving power revealed a high efficiency of CBDP markers in analyzing genetic diversity among different wheat genotypes. The diversity indexes including polymorphic loci percent, number of observed and effective alleles, Shannon’s index and gene diversity among different populations were 76.24%, 1.67, 1.49, 0.42 and 0.28, respectively. These essentially coincided with the analysis of molecular variance results, indicating that 86, 68, and 59.46% of genetic variation were found within two <i>Aegilops</i> and <i>Triticum</i> genera and their populations, respectively. Genetic relationships inferred from cluster analysis was matched with STRUCTURE analysis, disclosing the accessions were grouped based on their genomic constitution. Furthermore, these results were confirmed by principal coordinate analysis (PCoA). Taken together, our results suggest that CBDP markers will be useful for genetic diversity assessment in the domesticated and wild relatives of wheat.</p