ALLELIC VARIATIONS OF SOS, HVNHX AND SDO GENES IN SOME BARLEY (Hordeum Vulgare L.) GENOTYPES

This study has been carried out at the Biotechnology Lab., Department of Field Crops, Faculty of Agriculture, Damascus University during the growing season 2019 - 2020, in order to detect the variations of SOS, HVNHX and SDO genes in different barley genotypes. Clear variations in the SOS, HVNHX and SDO genes, which are responsible for salinity tolerance were found among the investigated genotypes. It has been found that the variation in the amplicon size between loci per gene was very high in some cases, while there was a high degree of symmetry in other cases, and could be easily distinguished on 2% Agarose gel. The PCR results for the SOS genes (SOS1, SOS2, SOS3), HVNHX genes (HVNHX1, HVNHX2, HVNHX3) and SDO genes (Cu/Zn SODII, Cu/Zn SODI, CAT, GRI , APXIII) have shown only one morphological pattern in most of the studied genotypes, while revealed two patterns for the SOS3 gene, but the rest of genes (HVNHX1, HVNHX2, HVNHX3 Cu/Zn SODI, CAT) exhibited only one morphological pattern. The SOS3 was superior in the number of polymorphic patterns, as the number of total patterns was 14 in all the studied genotypes, but the Cu/Zn SODI showed the least number of polymorphic patterns with only 1 pattern, while the largest number (7 patterns) was detected in the genotype (H9), but the two genotypes Fourat9 and Fourat7 showed only one polymorphic pattern.

​Best Linear Unbiased Prediction with Additive Main and Multiplicative Interaction for Stability Analysis of Barley Genotypes Evaluated in Coordinated Program

Background: Additive main and multiplicative interaction (AMMI) analysis had been exploited for multi environment trials for most of the crops. Usage of the best linear unbiased prediction (BLUP), along with AMMI tools, of the genotypes would improve the estimation of interaction effects. Methods: AMMI based measures of adaptability have been enriched with the incorporation of BLUP of genotypes by new Superiority index that allowed variable weights for stability and yield of genotypes. Result: Stability measure weighted average of absolute scores (WAASB) based on all significant interaction principal components ranked suitability of KB1754, RD3000, NDB1445 genotypes. Superiority index while weighting 0.65 and 0.35 for mean yield and stability arranged DWRB201, NDB1445, RD2552 as of stable high yield performance of barley genotypes. Corrected measure Modified AMMI Stability Value (MASV1) found RD2552, DWRB201, KB1762 and Modified AMMI Stability Value (MASV) ranked DWRB201, RD2552, KB1762. ASTAB measure achieved the desirable lower values for DWRB201 DWRB207, HUB268 genotypes. Biplot graphical analysis based on 60.7% of variation of the stability measures observed MASV1, ASTAB (AMMI based stability parameter), EV(Averages of the squared eigenvector values), SIPC (Sums of the absolute value of the IPC scores), Za (Absolute value of the relative contribution of IPCs to the interaction), W3, WAASB and MASV had been clubbed together. For the second year lower value of WAASB measure had observed for RD3016, KB1815 HUB273. Ranking of genotypes as per Superiority index found RD3017, RD2907, HUB274 as of stable high yield performance. Genotypes RD3017, RD2907 and NDB1173 pointed out by MASV1 while RD3017, RD2907, NDB1173 identified by MASV as the genotypes of choice. RD3017 NDB1173, RD2907 genotypes were selected as per values of ASTAB measure. Total of 71.8% of variation of the considered measures in biplot analysis expressed larger cluster comprised of AMMI based measures and a separate cluster of Superiority indexes as per mean, Geometric Adaptability Index (GAI) and HMGV also observed.

Mechanistic Insights into Potassium-Conferred Drought Stress Tolerance in Cultivated and Tibetan Wild Barley: Differential Osmoregulation, Nutrient Retention, Secondary Metabolism and Antioxidative Defense Capacity

Keeping the significance of potassium (K) nutrition in focus, this study explores the genotypic responses of two wild Tibetan barley genotypes (drought tolerant XZ5 and drought sensitive XZ54) and one drought tolerant barley cv. Tadmor, under the exposure of polyethylene glycol-induced drought stress. The results revealed that drought and K deprivation attenuated overall plant growth in all the tested genotypes; however, XZ5 was least affected due to its ability to retain K in its tissues which could be attributed to the smallest reductions of photosynthetic parameters, relative chlorophyll contents and the lowest Na+/K+ ratios in all treatments. Our results also indicate that higher H+/K+-ATPase activity (enhancement of 1.6 and 1.3-fold for shoot; 1.4 and 2.5-fold for root), higher shoot K+ (2 and 2.3-fold) and Ca2+ content (1.5 and 1.7-fold), better maintenance of turgor pressure by osmolyte accumulation and enhanced antioxidative performance to scavenge ROS, ultimately suppress lipid peroxidation (in shoots: 4% and 35%; in roots 4% and 20% less) and bestow higher tolerance to XZ5 against drought stress in comparison with Tadmor and XZ54, respectively. Conclusively, this study adds further evidence to support the concept that Tibetan wild barley genotypes that utilize K efficiently could serve as a valuable genetic resource for the provision of genes for improved K metabolism in addition to those for combating drought stress, thereby enabling the development of elite barley lines better tolerant of abiotic stresses.

Comparative transcriptome analysis reveals compatible and recalcitrant genotypic response of barley microspore-derived embryogenic callus toward Agrobacterium infection

Background The Agrobacterium mediated transformation has been routinely used in lots of plant species as a powerful tool to deliver genes of interest into a host plant. However, the transformation of elite and commercially valuable cultivar is still limited by the genotype-dependency, and the efficiency of Agrobacterium infection efficiency is crucial for the success of transformation. Results In this study, the microspore-derived embryogenic calli (MDEC) of barley elite cultivars and breeding lines were employed as unique subjects to characterize the genotypic response during Agrobacterium infection process. Our results identified compatible barley genotypes (GanPi 6 and L07, assigned as GP6-L07 group) and one recalcitrant genotype (Hong 99, assigned as H99) for the Agrobacterium strain LBA4404 infection using GUS assay. The accumulation trend of reactive oxygen species (ROS) was similar among genotypes across the time course. The results of RNA-seq depicted that the average expressional intensity of whole genomic genes was similar among barley genotypes during Agrobacterium infection. However, the numbers of differentially expressed genes (DEGs) exhibited significant expressional variation between GP6-L07 and H99 groups from 6 to 12 h post-inoculation (hpi). Gene ontology (GO) enrichment analysis revealed different regulation patterns for the predicted biological processes between the early (up-regulated DEGs overrepresented at 2 hpi) and late stages (down-regulated DEGs overrepresented from 6 to 24 hpi) of infection. KEGG analysis predicted 12 pathways during Agrobacterium infection. Among which one pathway related to pyruvate metabolism was enriched in GP6 and L07 at 6 hpi. Two pathways related to plant hormone signal transduction and DNA replication showed expressional variation between GP6-L07 and H99 at 24 hpi. It was further validated by qRT-PCR assay for seven candidate genes (Aldehyde dehydrogenase, SAUR, SAUR50, ARG7, Replication protein A, DNA helicase and DNA replication licensing factor) involved in the three pathways, which are all up-regulated in compatible while down-regulated in recalcitrant genotypes, suggesting the potential compatibility achieved at later stage for the growth of Agrobacterium infected cells. Conclusions Our findings demonstrated the similarity and difference between compatible and recalcitrant genotypes of barley MDEC upon Agrobacterium infection. Seven candidate genes involved in pyruvate metabolism, hormonal signal transduction and DNA replication were identified, which advocates the genotypic dependency during Agrobacterium infection process.

Variability of selected quantitative traits in new spring barley genotypes

The research included 19 breeding lines and 4 cultivars of spring barley from the preliminary field experiments harvested in 2020 in Radzików. All barley samples were characterized for the content of protein, non-starch polysaccharides (NSP) with soluble (S-NSP) and insoluble (I-NSP) fractions and β-glucan. Additionally, viscosity of water extracts (WEV) was measured to determine the functional properties of the grain. It was the most diverse parameter (CV = 27%) and was significantly correlated with β-glucan content (r = 0.50; for p <0.05). This dependence is shown by the results obtained for the grain of the Avatar cultivar and the RAH 744/19 breeding line, in which the content of β-glucan (5.3% and 4.8%, respectively), as well as the WEV (3.3 mPa.s and 3.0 mPa.s, respectively) were the highest. The lowest content of β – glucan (3.5%) and one of the lowest WEV values (1.4 mPa.s) were observed for KWS Jessie cultivar. Principal component analysis (PCA) showed a substantial impact of the two components PC1 and PC2 on the variability of the analyzed material showing significant variability of the 5 barley genotypes and confirmed the previous results of biochemical analyzes. Our results made it possible to indicate several genotypes that may constitute a source of variability in breeding works aimed at improving the quality of barley. Presented study also show that the grain of some new barley genotypes, with a favorable chemical composition from a fodder and brewing perspective, is a good material for future use in industry.

Barley Genotypes Vary in Stomatal Responsiveness to Light and CO2 Conditions

Changes in stomatal conductance and density allow plants to acclimate to changing environmental conditions. In the present paper, the influence of atmospheric CO2 concentration and light intensity on stomata were investigated for two barley genotypes—Barke and Bojos, differing in their sensitivity to oxidative stress and phenolic acid profiles. A novel approach for stomatal density analysis was used—a pair of convolution neural networks were developed to automatically identify and count stomata on epidermal micrographs. Stomatal density in barley was influenced by genotype, as well as by light and CO2 conditions. Low CO2 conditions resulted in increased stomatal density, although differences between ambient and elevated CO2 were not significant. High light intensity increased stomatal density compared to low light intensity in both barley varieties and all CO2 treatments. Changes in stomatal conductance were also measured alongside the accumulation of pentoses, hexoses, disaccharides, and abscisic acid detected by liquid chromatography coupled with mass spectrometry. High light increased the accumulation of all sugars and reduced abscisic acid levels. Abscisic acid was influenced by all factors—light, CO2, and genotype—in combination. Differences were discovered between the two barley varieties: oxidative stress sensitive Barke demonstrated higher stomatal density, but lower conductance and better water use efficiency (WUE) than oxidative stress resistant Bojos at saturating light intensity. Barke also showed greater variability between treatments in measurements of stomatal density, sugar accumulation, and abscisic levels, implying that it may be more responsive to environmental drivers influencing water relations in the plant.

Dosage of duplicated and antifunctionalized homeobox proteins influences spikelet development in barley

Illuminating the mechanisms of inflorescence architecture of grain crops that feed our world may strengthen the goal towards sustainable agriculture. Lateral spikelet development of barley (Hordeum vulgare L.) is such an example of a floral architectural trait regulated by VRS1 (Vulgare Row-type Spike 1 or Six-rowed Spike 1, syn. HvHOX1). The mechanistic function of this gene and its paralog HvHOX2 on spikelet development is still fragmentary. Here, we show that these duplicated transcription factors (TFs) have contrasting nucleotide diversity in various barley genotypes and several Hordeum species. Despite this difference, both proteins retain their basic properties of the homeodomain leucine zipper class I family of TFs. During spikelet development, these genes exhibit similar spatiotemporal expression patterns yet with anticyclic expression levels. A gene co-expression network analysis suggested that both have an ancestral relationship but their functions appear antagonistic to each other, i.e., HvHOX1 suppresses whereas HvHOX2 rather promotes spikelet development. Our transgenic promoter-swap analysis showed that HvHOX2 can restore suppressed lateral spikelets when expression levels are increased; however, at its low endogenous expression level, HvHOX2 appears dispensable for spikelet development. Collectively, this study proposes that the dosage of the two antagonistic TFs, HvHOX1 and HvHOX2, influence spikelet development in barley.

Response of Barley Genotypes to Fusarium Head Blight under Natural Infection and Artificial Inoculation Conditions

Forty-eight spring barley genotypes were evaluated for deoxynivalenol (DON) concentration under natural infection across 5 years at Harrington, Prince Edward Island. These genotypes were also evaluated for Fusarium head blight (FHB) severity and DON concentration under field nurseries with artificial inoculation of <i>Fusarium graminearum</i> by the grain spawn method across 2 years at Ottawa, Ontario, and one year at Hangzhou, China. Additionally, these genotypes were also evaluated for FHB severity under greenhouse conditions with artificial inoculation of <i>F. graminearum</i> by conidial suspension spray method across 3 years at Ottawa, Ontario. The objective of the study was to investigate if reactions of barley genotypes to artificial FHB inoculation correlate with reactions to natural FHB infection. DON concentration under natural infection was positively correlated with DON concentration (<i>r</i> = 0.47, <i>P</i> < 0.01) and FHB incidence (<i>r</i> = 0.56, <i>P</i> < 0.01) in the artificially inoculated nursery with grain spawn method. Therefore, the grain spawn method can be used to effectively screen for low DON. FHB severity, generated from greenhouse spray, however, was not correlated with DON concentration (<i>r</i> = 0.12, <i>P</i> > 0.05) under natural infection and it was not correlated with DON concentration (<i>r</i> = -0.23, <i>P</i> > 0.05) and FHB incidence (<i>r</i> = 0.19, <i>P</i> > 0.05) in the artificially inoculated nursery with grain spawn method. FHB severity, DON concentration, and yield were affected by year, genotype, and the genotype × year interaction. The effectiveness of greenhouse spray inoculation for indirect selection for low DON concentration requires further studies. Nine of the 48 genotypes were found to contain low DON under natural infection. Island barley had low DON and also had high yield.