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The cultivated barley ranks fourth cereal crop in the world. The demand for higher-yielding, nutritious, and better-adapted crop varieties has increased the need to exploit genebanks diversity. Thus, assessing the genetic diversity of barley is essential to determine the genetic relationship between lines and deploy novel alleles in breeding programs. Here, we used 14 polymorphic Simple Sequence Repeat (SSR) markers to assess genetic diversity, genetic relationship, and population structure of 113 barley lines originated from 14 countries, and the majority from Africa. The average alleles per locus of 5.36, Polymorphism Information Content (PIC) of 0.57, and genetic diversity of 0.61 indicate a high degree of genetic variation in this collection. The Analysis of Molecular Variance AMOVA showed genetic variation within countries to be higher (74%) than among countries (26%). The STRUCTURE analysis was consistent with neighbor-joining clustering and principal components analysis, which identified three main subpopulations clustered primarily according to their geographic origin. Growing environments, migration between and within countries might have caused a considerable genetic diversity observed in the North African barley germplasm. The results of this study contribute to the conservation and utilization of these barley germplasm. [ABSTRACT FROM AUTHOR]

Wheat and barley are the most important cereal crops in Morocco and in North Africa. Their production is constrained by several biotic and abiotic stresses. Climate change has further aggravated these problems. Since the landraces, old and newer varieties are reservoirs of variability and adaptive traits required for breeding for resistances to stresses and adaptation of climate change, we screened 400 bread wheat and 295 durum wheat accessions at Sidi El Aidi (Morocco) during 2015--16 and identified 4 lines (Kharouba, 2837, CWI77963 and CWI9941) highly resistant and 290 resistant/moderately resistant to yellow rust respectively. Similarly, Screening of 452 accessions of barley in the same location resulted in the identification of 116 moderately resistant accessions to net blotch disease. Some of the identified resistance sources are being used to make genetic crosses for studying genetics of resistance, developing improved cultivars and to increase cultivar diversity in the country which can enhance 'life of the resistant cultivars' and adaptation to climate change. As a first step and baseline information, we evaluated phenotypic and genotypic diversity of a set of 20 improved bread wheat cultivars released in Morocco since 1980s. The results revealed that many of the wheat cultivars were susceptible to prevailing biotypes of the Hessian fly and yellow rust. The genotyping of the 20 Moroccan wheat cultivars using 14 microsatellite markers revealed 59 alleles (Mean = 4.21), substantial genetic diversity (Range = 0 to 0.895, Mean = 0.576) and genetic distance (0.143 to 1.00). However, total number of alleles decreased (8.3%) in the cultivars developed during recent period (1990s) compared to that of 1980s. In order to enhance biotic and abiotic stress tolerance, end-use quality and allelic diversity of wheat cultivars in Morocco, 8 exotic wheat cultivars having various useful known genes were deployed and being used to make crosses with Moroccan cultivars. Further, these Moroccan cultivars and the exotic cultivars were characterized using 47 gene specific or functional markers and 7 linked random DNA markers associated with 21 loci of the most important traits for wheat breeding. The functional marker analysis revealed that 35 and 45% of the Moroccan cultivars, respectively have the rust resistance genes (Lr34/Yr18/ Pm38) and dwaring genes (Rht1b or Rht2b allele). The desired marker alleles for genes Lr37/Yr17/Sr38, Sr24 and Yr36 were present only in the exotic cultivars and absent in Moroccan cultivars. 25% of cultivars had 1BL.1RS translocation. 70% of the wheat cultivars had Ppo-D1a and Ppo-A1b associated with low polyphenol oxidase activity. 10% of cultivars showed presence of a random DNA marker allele (175 bp) linked to Hessian fly resistance gene H22. Integration of molecular markers within traditional breeding systems had enabled to select superior genotypes for traits that are difficult to select based solely on phenotype or to pyramid desirable combinations of genes into a single genetic background. The targeted crosses were made and subsequent generations were carried forward through traditional breeding systems and also in some cases through doubled haploids (DH) to speed up development of homozygous plants. Though marker-assisted breeding (MAB) can be applied to all segregating generations, we most commonly applied to early generations, including haploids, F2, BC1F1, BC1F2 and the F1 of complex crosses to enrich populations with favourable genes and their combinations. MAB also offered the opportunity to hasten transfer of desirable alleles from un-adapted exotic genetic backgrounds into a desirable germplasm through crossbreeding. Marker-linked loci responsible for traits such as resistance to diseases, quality and phenology were selected in the segregating populations and the desired genotypes were carried forward until they reach nearly homozygous. Once, the selected genotypes reach F6 or later generations, they were validated for the selected traits under field conditions. Only lines expressing desired phenotypes were selected for seed increase and subsequent preliminary yield trials and multilocation trials. In conclusion, application of MAB and DH technologies greatly enhanced efficiency and effectiveness of utilization of the germplasm and enhanced genetic gains in the breeding programs. [ABSTRACT FROM AUTHOR]