Evaluation of a Set of Hordeum vulgare subsp. spontaneum Accessions for β-Glucans and Microelement Contents

Barley is one of the oldest domesticated crops in the world and is mainly used for feed and malt and to a lesser extent as food. The use of barley as food is a tradition in communities in some countries of North Africa, Europe, and Asia. However, due to the health-promoting properties of barley grain, there is an increasing interest in such use. The International Center for Agricultural Research in the Dry Areas (ICARDA) has a global mandate for barley improvement and holds rich in-trust collections of cultivated and wild Hordeum species. The present study aims to evaluate 117 accessions of Hordeum spontaneum for their contents of β-glucan and microelements for breeding new varieties with enhanced nutritional value. The bulked seed accessions of Hordeum spontaneum were grown over two seasons, and the single plant derived seeds from these accessions were compared to 36 elite lines and varieties of cultivated barley in the second season in Morocco. The results showed large differences in β-glucan and microelements in both the bulk and the single plant seed accessions. The contents of β-glucans ranged from 1.44 to 11.3% in the Hordeum spontaneum accessions and from 1.62 to 7.81% in the cultivated barley lines. Large variations were found for the microelements content, but no differences were noticed between the wild and the cultivated species. However, some accessions of Hordeum spontaneum had higher combined contents of Iron, Zinc, and Selenium. Such accessions are used in interspecific crosses to develop biofortified barley germplasm and varieties.

Salinity tolerance evaluation of barley germplasm for marginal soil utilization

One greenhouse experiment was conducted to assess the tolerance to salinity and water deficit stresses of 184 barley varieties (breeding lines or registered varieties). Also, a 2-year field experiment was conducted to evaluate the growth and yield components of 16 of these varieties, representing tolerant, intermediate tolerant and susceptible ones, grown simultaneously in saline and non-saline soils. In the greenhouse, the K-means cluster analysis shown that 17 varieties were tolerant, 72 varieties intermediate tolerant, 16 varieties intermediate susceptible and 79 varieties susceptible. In the field, soil salinity reduced the germination of the barley varieties except for the varieties ICB 100126, Scarlett and Meteor. Barley varieties grown in the saline soil produced 33.2-to 83.4% lower dry biomass, 0.0-to 78.9% fewer ears and 0.0-to 81.5% lower grain yield than those of varieties grown in the non-saline soil. In the saline soil, the greatest grain yield was provided by the vars. Galt Brea 'S' and ICB 100126 (4.87 and 4.31 t ha-1, respectively), without significant differences between saline and non-saline soils. In most barley varieties, chlorophyll content and photosystem II quantum yield were greater under saline than under non-saline conditions. The results of this research indicated that, in barley germplasm, a remarkable genetic variation exists which would contribute to barley production in saline soils. Highlights - The salinity tolerance of 184 barley varieties was investigated. - There was great variability to salinity tolerance among barley germplasm. - There were barley varieties which grown in saline soil without significant yield reduction. - Barley could be an alternative crop system in soils with increased salinity.

The effect of responses to vernalization, photoperiodism, and earliness per se of barley accessions from Dagestan on the duration of the period from shooting to heading

Background. Paratypic variability of the development rates of barley accessions from the Republic of Dagestan was analyzed for five years in the Northwe st of Russia (Pushkin, St. Petersburg) and in the North Caucasus (Derbent, Dagestan). Responses to vernalization, photoperiodism and earliness per se were tested in contrasting environments to assess their effect on barley development. Such studies make it possible to identify valuable adaptable plant forms in the barley germplasm collection for further use in breeding practice.Materials and methods. In Dagestan, the duration of the period from shooting to heading was measured for 12 samples of barley accessions in winter and spring sowing trials. Twenty samples sown in spring in both regions were compared. An empirical indicator of plant development rate was used for barley: the criterion “the number of days by which the period from shooting to heading of an accession exceeds the minimum across a sample” (DPSH).Results and conclusions. Early barley accessions with a low norm of responsiveness were identified: k-3772, k-15013, k-15034, k-15036, k-15186, k-15192, k-21803 and k-23785 – they combined weak sensitivity to a short photoperiod and vernalizing temperatures, so they are promising for breeding in regions where the length of the growing season is a limiting factor. The effect of the responses of barley accessions from Dagestan to vernalization and a short photoperiod on the duration of the period from shooting to heading was on average 8 (5.1–10.6) days and on their earliness per se 6 (4.8–8.2) days. Paratypic variability reflects the range of variation for these indicators. In Dagestan, vernalization temperatures and insensitivity to a short day are the main factors determining the earliness of local barleys in their native environment.

Evaluation of barley genotypes for the content of β-glucans in grain and other valuable features in Eastern Siberia

Background.The aim of the research was to identify barley germplasm accessions with the minimum and maximum content of β-glucans in their grain in combinations with other improved useful traits.Material and methods.The material for analysis were 18 hulled and 8 naked barley accessions of various ecogeographic origin from the collection of the N.I. Vavilov AllRussian Institute of Plant Genetic Resources (VIR), which were grown under the conditions of Eastern Siberia in 2016–2018.Results.Hulled accessions yielded grains with β-glucan content from 3.18 to 4.51%; naked ones, from 3.18 to 5.21%. According to the minimum value of the studied qualitative trait (3.18–3.43%), cultivars of Siberian breeding were identified: ‘Mayak’ (k-29622, Krasnoyarsk Territory) and ‘Tarsky 3’ (k-30719, Omsk Province), plus cv. ‘AC Albright’ (k-30599, Canada); according to the maximum value (5.06–5.21%), the naked accessions Nudum 155 (k-13328, Ukraine) and ‘Nudum 95’ (k-31125, Chelyabinsk Province). The highest protein content in grain (16.63–18.36%) was found in the accessions Nudum 155, Nudum 7566 (k-29453, Kyrgyzstan) and ‘Nudum 95’. The accessions Nudum 155 and ‘Nudum 95’ were characterized by combined high contents of β-glucans and protein in their grain. Early maturity and increased productivity were shown by the cultivars ‘Tarsky 3’, ‘Kolchan’ (k-31039, Altai Territory), ‘Zolotnik’ (k-30845, Altai Territory), ‘Abalak’ (Krasnoyarsk Territory, Tyumen Province), and ‘AC Albright’ (Canada). A significant positive relationship was found between the content of β-glucans and the weight of 1000 grains in both forms of barley.Conclusion.According to β-glucan content combined with other valuable characteristics in grain, the accessions ‘Mayak’, ‘Tarsky 3’ and ‘AC Albright’ are of interest for the improvement of fodder cultivars, while ‘Nudum 95’ and Nudum 155 are promising for breeding for food.

Quantitative Trait Loci Mapping for Vigour and Survival Traits of Barley Seedlings after Germinating under Salinity Stress

Seed germination and seedling establishment are the most critical stages in the barley (Hordeum vulgare ssp. vulgare L.) life cycle that contribute substantially to grain yield. These two phases are exposed to several forms of environmental stresses such as salinity due to high level of salt accumulation in the soil rhizosphere where seed germination takes place and seedlings emerge from. Previously, we have reported genotypic variability and independent QTLs associated with salinity tolerance at seedling and germination stages. However, genotypic studies on revival of a seedling germinating under salinity stress are yet to close the lack of information between germination and seedling stages. Here, we attempt to close the genetic gap by targeting early seedling survival traits in barley after germination under salinity (NaCl) stress and the various seedling vigour indices. Seedling vigour parameters formed the basis for Quantitative trait locus (QTL) linkage mapping in 103 Doubled Haploid (DH) lines of CM72/Gairdner population, and validated the phenotypic response using a selected diverse panel of 85 barley germplasm. The results indicate that 150 mM NaCl stress significantly reduced all the recorded phenotypic traits compared to 75, 90 and 120 mM NaCl. In both DH population and diversity panel barley germplasm, the highest percentage reduction was recorded in shoot length (65.6% and 50.3%) followed by seedling vigour index length (56.5% and 41.0%), while root length (28.6% and 15.8%) and root dry weight (29.3% and 28.0%) were least reduced when control was compared to150 mM NaCl stress treatment. Six QTLs containing 13 significant markers were detected in the DH population, 3 on chromosomes 1H, 8 on 3H and 2 on 4H with LOD values ranging from 3 to 8 associated with seedling survival traits under salinity stress. Three QTLs one on 1H and two on 3H with closely linked significant markers (Bmac0032, bPb-9418 and bPb-4741), (bPb-4576 and bPb-9624) and (bPb-3623, bPb-5666 and bPb-6383) for 1H and two on 3H respectively formed the regions with high possibility of candidate genes. A QTL on 3H flanked with markers bPb-4576 and bPb-9624 that were detected in more than one salinity survival trait and were closely linked to each other will form a basis for detailed studies leading to gene functional analysis, genetic transformation and marker assisted selection (MAS).

The barley pan-genome reveals the hidden legacy of mutation breeding

Genetic diversity is key to crop improvement. Owing to pervasive genomic structural variation, a single reference genome assembly cannot capture the full complement of sequence diversity of a crop species (known as the ‘pan-genome’1). Multiple high-quality sequence assemblies are an indispensable component of a pan-genome infrastructure. Barley (Hordeum vulgare L.) is an important cereal crop with a long history of cultivation that is adapted to a wide range of agro-climatic conditions2. Here we report the construction of chromosome-scale sequence assemblies for the genotypes of 20 varieties of barley—comprising landraces, cultivars and a wild barley—that were selected as representatives of global barley diversity. We catalogued genomic presence/absence variants and explored the use of structural variants for quantitative genetic analysis through whole-genome shotgun sequencing of 300 gene bank accessions. We discovered abundant large inversion polymorphisms and analysed in detail two inversions that are frequently found in current elite barley germplasm; one is probably the product of mutation breeding and the other is tightly linked to a locus that is involved in the expansion of geographical range. This first-generation barley pan-genome makes previously hidden genetic variation accessible to genetic studies and breeding.

Validating molecular markers for barley leaf rust resistance genes Rph20 and Rph24

Improving resistance to barley leaf rust (caused by Puccinia hordei) is an important breeding objective in most barley growing regions worldwide. The development and subsequent utilization of high-throughput polymerase chain reaction (PCR) based co-dominant molecular markers remains an effective approach to select genotypes with multiple effective resistance genes, permitting efficient gene deployment and stewardship. The genes Rph20 and Rph24, which confer widely effective adult plant resistance (APR) to leaf rust, are common in European and Australian barley germplasm (often in combination), and act interactively to confer high levels of resistance. Here we report on the development and validation of co-dominant insertion-deletion (indel) based PCR markers that are highly predictive for the resistance alleles Rph20.ai and Rph24.an (both referred to as Rph20 and Rph24).