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In cereals, resistance and tolerance to salinity are qualities that allow their cultivation in arid and semi-arid regions. Hence, we sought to select salt stress-resistant barley genotypes by applying sub-lethal NaCl concentrations and observing their effect on germination. This work was carried out using parent spring barley genotype (Hordeum vulagre L.) namely Tamelalt, and its doubled haploids progeny. Salt stress resistance was tested on seeds germination in Petri dishes provided with filter paper containing increasing concentrations of salt (0, 5, 10, and 15 g.L-1) for 10 days at 25°C. The doubled haploids progeny derived from Tamelalt showed to be the most tolerant to salt stress with a germination rate under the most severe salt stress conditions (NaCl 15 g.L-1), while the parent genotype Tamelalt was the least tolerant with a germination rate of only 26.67% under the same stress. Principal component analysis and hierarchical cluster analysis allowed the separation of DH lines and parent genotype. Two groups were identified. The DH lines were completely different from the parent genotype. [ABSTRACT FROM AUTHOR]

To study the relationships of grain yield and some of agro-morphological traits in 40 doubled haploid (DH) lines along with parental and three check genotypes in a randomized complete block design with two replications under two water regimes (normal and stress) were evaluated during 2011-2012 and 2012-2013 growing seasons. Combined analysis of variance showed significant difference for all the traits in terms of the year, water regimes, lines, and and line × year. Comparison of group means, between non-stress and stress conditions, showed that DH lines had the lowest reduction percentage for the number of grains per spike, thousand grain weight, grain yield and biological yield as opposed to check genotypes. The correlation between grain yield with biological yield, harvest index, thousand grain weight, and hectoliter of kernel weight in both conditions, were highly significant and positive. Based on stepwise regression the peduncle length, number of seeds per spike, thousand seed weight, and hectoliter of kernel weight had important effect on increasing seed yield. The result of path analysis showed that these traits had the highest direct effect on grain yield. Based on mean comparisons of morphological characters as well as STI and GMP indices it can be concluded that lines No.11, 13, 14, 24, 29, 30, 35 and 39 were distinguished to be desirable lines for grain yield and their related traits and also tolerant lines in terms of response to drought stress conditions.

The present study investigated drought-induced changes in proteome profiles of ten DH lines of winter barley, relatively varied in water deficit tolerance level. Additionally, the parameters describing the functioning of the photosynthetic apparatus and the activity of the antioxidative system were analysed. Water deficit (3-week growth in soil with water content reduced to ca. 35%) induced significant changes in leaf water relations and reduced photosynthetic activity, probably due to decreased stomatal conductance. It was associated with changes in protein abundance and altered activity of antioxidative enzymes. From 47 MS-identified proteins discriminating more tolerant from drought-sensitive genotypes, only two revealed distinctly higher while seven revealed lower abundance in drought-treated plants of tolerant DH lines in comparison to sensitive ones. The majority were involved in the dark phase of photosynthesis. Another factor of great importance seems to be the ability to sustain, during drought stress, relatively high activity of enzymes (SOD and CAT) decomposing reactive oxygen species and protecting plant cell from oxidative damages. Low molecular weight antioxidants seem to play less important roles. Our findings also suggest that high tolerance to drought stress in barley is a constitutively controlled trait regulated by the rate of protein synthesis and their activity level. Biological significance According to our knowledge, this is the first comparative proteomic analysis of drought tolerance performed for the model set of several winter barley doubled haploid (DH) lines. We analysed both the drought impact on the protein pattern of individual winter barley DH lines as well as comparisons between them according to their level of drought tolerance. We have identified 47 proteins discriminating drought-tolerant from drought-sensitive genotypes. The majority was involved in the dark phase of photosynthesis. Another factor of great importance in our opinion seems to be the ability to sustain, during drought stress, relatively high activity of antioxidative enzymes (SOD and CAT) decomposing reactive oxygen species and protecting plant cell from oxidative damages. Our findings also suggest that high tolerance to drought stress in barley is a constitutively-controlled trait regulated by the rate of protein synthesis and their activity level. [ABSTRACT FROM AUTHOR]

Epistasis, an additive-by-additive interaction between quantitative trait loci, has been defined as a deviation from the sum of independent effects of individual genes. Epistasis between QTLs assayed in populations segregating for an entire genome has been found at a frequency close to that expected by chance alone. Recently, epistatic effects have been considered by many researchers as important for complex traits. In order to understand the genetic control of complex traits, it is necessary to clarify additive-by-additive interactions among genes. Herein we compare estimates of a parameter connected with the additive gene action calculated on the basis of two models: a model excluding epistasis and a model with additive-by-additive interaction effects. In this paper two data sets were analysed: 1) 150 barley doubled haploid lines derived from the Steptoe x Morex cross, and 2) 145 DH lines of barley obtained from the Harrington x TR306 cross. The results showed that in cases when the effect of epistasis was different from zero, the coefficient of determination was larger for the model with epistasis than for the one excluding epistasis. These results indicate that epistatic interaction plays an important role in controlling the expression of complex traits.

Epistasis, is the interaction between alleles from two or more loci determining complex traits, and thus plays an important role in the development of quantitative traits of crops. In mapping studies of inbreeding species epistasis is usually defined as the interactions between quantitative trait loci with significant additive gene effects. Indeed, in many studies, genes with small effects do not come into the final model and thus the total epistasis interaction effect is biased. Many loci may not have a significant direct effect on the trait under consideration, but they may still affect trait expression by interacting with other loci. In this paper the benefits of using all loci, not only the loci with significant main effects, for estimation of the epistatic effects are presented. The particular examples are with doubled haploids lines and so are restricted to homozygotes and thus additive genetic effects and additive × additive interactions. Numerical analyses were carried out on three populations of doubled haploid lines of barley ( Hordeum vulgare L.): 120 doubled haploid lines from the Clipper × Sahara 3771 cross, 145 doubled haploid lines from the Harrington × TR306 cross and 150 doubled haploid lines from the Steptoe × Morex cross. In total, 157 sets of observations were analyzed and altogether 728 pairs of loci were observed for the three datasets. [ABSTRACT FROM AUTHOR]

In this paper the relationships between genotypic diversity and phenotypic diversity of four quantitative traits of doubled haploid lines of barley (Hordeum vulgare L.) were studied. The lack of significant relationships was found for three observed traits. [ABSTRACT FROM AUTHOR]

Four barley doubled haploid populations were produced by anther culture from the reciprocal crosses between two six-row barley cultivars, ‘Plaisant’ and ‘Orria’; the doubled haploid lines (DHLs) derived from each cross were subsequently assigned to weak or vigorous populations according to the weak or vigorous nature of the originating embryos. Well-formed embryos at day 25 on the induction medium were considered vigorous, whereas embryos maturing later were considered weak. The classification of vigorous and weak was closely associated with the ratio of green to albino plantlets regenerated. A random set of 25 DHLs from each of the four populations were selected for field testing in a replicated trial. Furthermore, a second set consisting of a total of 454 unreplicated DHLs from the four populations were also field assessed for grain yield. Distortion during in vitro culture may impede regeneration of a random array of microspores from a given cross, and may bias genetic estimates of specific trait/marker association in genetic studies. However, no significant differences were detected in this study among the four populations for days to heading, height, grain yield and thousand-kernel-weight when measured on the replicated trial of 100 DHLs, nor for grain yield in the second collection of 454 entries. This suggests that the likelihood of producing improved agronomic pure lines is independent of the direction of crossing and, more importantly, independent of the time when embryos matured in the induction media, at least for these particular six-row cultivars and for the anther culture method used. [ABSTRACT FROM AUTHOR]

Salt stress is one of the major environmental factors limiting cereal productivity in worldwide agriculture. Evaluating and selecting salt tolerant genotypes are an effective approach to overcome yield losses. This study aimed to characterize and compare phenotypic variability among doubled haploid (DH) barley lines and their parent under different salinity conditions (T1 = 0, T2 = 3, and T3 = 6 g.L−1 NaCl). The DH lines were produced by in vitro selection callus in a regeneration medium supplemented with 5 g.L−1 NaCl. Fifteen measured traits were assessed including physiological, biochemical, and agro-morphological traits. Biplot analysis was used to visualize the relationships among the studied traits and to evaluate the relative performance of each genotype. Pearson's correlation followed by stepwise and path analysis were then performed successively to identify appropriate criteria that most influence grain yield. The results showed a wide range of variation for the measured traits, indicating the existence of a phenotypic variation between the tested genotypes. Salinity significantly affected the parent more than the DH lines. Stepwise regression analysis indicated that 99% of the variation in grain yield was explained by K+/Na+ ratio, number of fertile spikes per plant, number of grains per spike, plant height, and proline content. However, the path coefficient revealed that number of fertile spikes per plant and number of grains per spike were indicative of salt tolerance in barley. Based on stepwise and path analysis results, the tested genotypes were ranked using salt tolerance index. The salt tolerant DH lines could be recommended as novel genetic resources in breeding programs. • A set of agro-physiological and biochemical traits was used to differentiate salt tolerant genotypes between doubled haploid barley lines and their parent. • Salt stress caused significant increase in proline, Na+, and decrease K+, stomatal conductance, and chlorophyll contents. • Salt stress reduced significantly yield and yield components. • Fertile tiller number, number of grain per spike, and K+/Na+ ratio were the major traits influencing grain yield. • The doubled haploid barley lines exhibited superiority in salinity tolerance compared with their parent. [ABSTRACT FROM AUTHOR]

Plant tolerance to environmental stress is determined by a very complicated network composed of many intra- and extracellular factors. The aim of this study was to select candidate genes involved in responses to freezing and drought in barley on the basis of previous proteomic studies and to analyze changes in their expression caused by application of both stress factors. Six candidate genes for freezing tolerance (namely the genes encoding elongation factor 1 alpha (EF1A), ferredoxin-NADP reductase, a 14-3-3a protein, β-fructofuranosidase, CBF2A and CBF4B) and six for drought tolerance (encoding transketolase, periplasmic serine protease, triosephosphate isomerase, a protein with a co-chaperon region (GroEs), pfam14200 and actin) were chosen arbitrarily on the basis of in silico bioinformatic analyses. The expression levels of these genes were measured under control and stress conditions in six DH (doubled haploid) lines with differing freezing and drought tolerance. The results of gene expression analysis confirmed the roles of the candidate genes preselected in this study on the basis of previous proteome analysis in contributing to the differences in freezing and drought tolerance observed in the studied population of DH lines of winter barley. [ABSTRACT FROM AUTHOR]