Exploring Wild Hordeum spontaneum and Hordeum marinum Accessions as Genetic Resources for Fungal Resistance

Abstract

Crop Wild Relatives (CWRs), as potential sources of new genetic variants, are being extensively studied to identify genotypes that will be able to confer resistance to biotic stresses. In this study, a collection of barley wild relatives was assessed in the field, and their phenotypic variability was evaluated using a Barley Description List, reflecting the identified ecosites. Overall, the CWRs showed significant field resistance to various fungal diseases. To further investigate their resistance, greenhouse tests were performed, revealing that several CWRs exhibited resistance against Fusarium culmorum, Pyrenophora teres, and Puccinia hordei G.H. Otth. Additionally, to characterize the genetic diversity within the collection, DNA polymorphisms at 21 loci were examined. We successfully employed barley-specific SSR markers, confirming their suitability for identifying H. spontaneum and even H. marinum, i.e., perennial species. The SSR markers efficiently clustered the investigated collection according to species and ecotypes, similarly to the phenotypic assessment. Moreover, SSR markers associated with disease resistance revealed different alleles in comparison to those found in resistant barley cultivars. Overall, our findings highlight that this evaluated collection of CWRs represents a valuable reservoir of genetic variability and resistance genes that can be effectively utilized in breeding programs.

Keywords: FHB; genetic resources; net blotch; resistance breeding; rust; wild barley.

Figure 1

Map of Hordeum spontaneum (stars) and H. marinum (empty pointers) accessions used for the investigation.

Figure 2

Association of 24 Hordeum samples based on a Gower distance dissimilarity matrix and average linkage clustering, along with the values of observed morphological, biological, and phenotypic descriptors. The two groups within the plot denoted by {1} and {2} represent the two main clusters in the dendrogram. The color keys on the left and top sides of the plot indicate the color scale and corresponding values for the selected characteristics. HSp in the row labels denotes the H. spontaneum samples, while the HMaM and HMaG labels highlight the H. marinum ssp. marinum and ssp. gussoneanum samples, respectively. Origin stands for abbreviation for country of origin of respective accession: AFG—Afghanistan; AZE—Azerbaijan; ESP—Spain; IRN—Iran; ISR—Israel; JOR—Jordan; MNG—Mongolia; PRT—Portugal; SYR—Syria; TJK—Tajikistan; TUR—Turkey.

Figure 3

Principal coordinate analysis based on a Gower dissimilarity matrix of phenological estimates for 24 accessions of H. spontaneum and H. marinum. The plot reveals the relationship between H. spontaneum accessions (represented in groups P1–P5) and H. marinum accessions (in groups P6–P7), and the diversity within each species. Origin stands for abbreviation for country of origin of respective accession: AFG—Afghanistan; AZE—Azerbaijan; ESP—Spain; IRN—Iran; ISR—Israel; JOR—Jordan; MNG—Mongolia; PRT—Portugal; SYR—Syria; TJK—Tajikistan; TUR—Turkey.

Figure 4

Association between the 24 Hordeum accessions, based on a simple matching dissimilarity matrix and unweighted neighbor-joining clustering method. The numbers above each node represent the bootstrap level of confidence (based on 1000 bootstrap replicates). The information at the end of each branch denotes the identification number of the sample, its country of origin, and the habitats of the samples. Numbers enclosed within curly brackets represent 7 main clades. Country of origin of respective accession is stated by its abbreviation: AFG—Afghanistan; AZE—Azerbaijan; ESP—Spain; IRN—Iran; ISR—Israel; JOR—Jordan; MNG—Mongolia; PRT—Portugal; SYR—Syria; TJK—Tajikistan; TUR—Turkey.

Figure 5

Principal coordinate analysis of 24 H. spontaneum and H. marinum accessions using SSR markers, based on a simple matching dissimilarity matrix and unweighted neighbor-joining algorithm with 1000 bootstrap replicates. The figure demonstrates the relationship between H. spontaneum (in S1–S4) and H. marinum (S5) accessions, and the diversity within species. Country of origin of respective accession is stated by abbreviations: AFG—Afghanistan; AZE—Azerbaijan; ESP—Spain; IRN—Iran; ISR—Israel; JOR—Jordan; MNG—Mongolia; PRT—Portugal; SYR—Syria; TJK—Tajikistan; TUR—Turkey.