Transcriptome analysis of Bipolaris sorokiniana - Hordeum vulgare provides insights into mechanisms of host-pathogen interaction.

Spot blotch disease incited by Bipolaris sorokiniana severely affects the cultivation of barley. The resistance to B. sorokiniana is quantitative in nature and its interaction with the host is highly complex which necessitates in-depth molecular analysis. Thus, the study aimed to conduct the transcriptome analysis to decipher the mechanisms and pathways involved in interactions between barley and B. sorokiniana in both the resistant (EC0328964) and susceptible (EC0578292) genotypes using the RNA Seq approach. In the resistant genotype, 6,283 genes of Hordeum vulgare were differentially expressed out of which 5,567 genes were upregulated and 716 genes were downregulated. 1,158 genes of Hordeum vulgare were differentially expressed in the susceptible genotype, out of which 654 genes were upregulated and 504 genes were downregulated. Several defense-related genes like resistant gene analogs (RGAs), disease resistance protein RPM1, pathogenesis-related protein PRB1-2-like, pathogenesis-related protein 1, thaumatin-like protein PWIR2 and defensin Tm-AMP-D1.2 were highly expressed exclusively in resistant genotype only. The pathways involved in the metabolism and biosynthesis of secondary metabolites were the most prominently represented pathways in both the resistant and susceptible genotypes. However, pathways involved in MAPK signaling, plant-pathogen interaction, and plant hormone signal transduction were highly enriched in resistant genotype. Further, a higher number of pathogenicity genes of B. sorokiniana was found in response to the susceptible genotype. The pathways encoding for metabolism, biosynthesis of secondary metabolites, ABC transporters, and ubiquitin-mediated proteolysis were highly expressed in susceptible genotype in response to the pathogen. 14 and 11 genes of B. sorokiniana were identified as candidate effectors from susceptible and resistant host backgrounds, respectively. This investigation will offer valuable insights in unraveling the complex mechanisms involved in barley- B. sorokiniana interaction.

Indian Gooseberry and Barley Sprout Complex Prevent Oxidative Stress and Photoaging of the Skin in Ultraviolet B-Irradiated SHK-I Mice.

This study investigated the protective effects of a complex of Indian gooseberry and barley sprout (IB complex) on oxidative stress and skin damage caused by ultraviolet B irradiation in SHK-I hairless mice. The study examined the impact of IB complex on skin hydration, wrinkle formation, and melanogenesis using enzyme-linked immunosorbent assay, real-time polymerase chain reaction, and western blot analysis. The IB complex reduced skin hydration loss and wrinkle formation, while also demonstrating enhanced antioxidant activities. The IB complex maintained skin hydration via upregulation of hyaluronic acid and ceramide synthesis, including the regulation of hyaluronic acid synthase, long-chain ceramide formation, dihydroceramide desaturase 1 activity, and type I collagen production. The IB complex prevented wrinkle formation via downregulating JNK and upregulating TGF-ß pathways. Moreover, IB complex blocked melanin production via inhibition of protein kinase A, cAMP response element-binding protein, and microphthalmia-associated transcription factor pathways. These results suggest that IB complex is a potential agent to protect the skin against photodamage caused by exposure to UVB radiation. The research protocols underwent approval from the Institutional Animal Care and Use Committee of Kyung Hee University (KHGASP-21-577), ensuring compliance with ethical standards.

A pipeline for identification of causal mutations in barley identifies Xantha-j as the chlorophyll synthase gene.

Thousands of barley (Hordeum vulgare L.) mutants have been isolated over the last century, and many are stored in gene banks across various countries. In the present work, we developed a pipeline to efficiently identify causal mutations in barley. The pipeline is also efficient for mutations located in centromeric regions. Through bulked-segregant analyses using whole genome sequencing of pooled F2 seedlings, we mapped two mutations and identified a limited number of candidate genes. We applied the pipeline on F2-mapping populations made from xan-j.59 (unknown mutation) and xan-l.82 (previously known). The Xantha-j (xan-j) gene was identified as encoding chlorophyll synthase, which catalyzes the last step in the chlorophyll biosynthetic pathway: the addition of a phytol moiety to the propionate side chain of chlorophyllide. Key amino-acid residues in the active site, including the binding sites of the isoprenoid and chlorophyllide substrates, were analyzed in an AlphaFold2-generated structural model of the barley chlorophyll synthase. Three allelic mutants, xan-j.19, xan-j.59, and xan-j.64 were characterized. While xan-j.19 is a one-base pair deletion and xan-j.59 is a nonsense mutation, xan-j.64 causes an S212F substitution in chlorophyll synthase. Our analyses of xan-j.64 and treatment of growing barley with clomazone, an inhibitor of chloroplastic isoprenoid biosynthesis, suggest that binding of the isoprenoid substrate is a prerequisite for the stable maintenance of chlorophyll synthase in the plastid. We further suggest that chlorophyll synthase is a sensor for coordinating chlorophyll and isoprenoid biosynthesis.

Integrative transcript to proteome analysis of barley during Ramularia collo-cygni leaf spot development identified several proteins that are related to fungal recognition and infection responses.

Introduction: Ramularia leaf spot (RLS) disease is a growing threat to barley cultivation, but with no substantial resistance identified to date. Similarly, the understanding of the lifestyle of Ramularia collo-cygni (Rcc) and the prediction of RLS outbreak severity remain challenging, with Rcc displaying a rather untypical long endophytic phase and a sudden change to a necrotrophic lifestyle. The aim of this study was to provide further insights into the defense dynamics during the different stages of colonization and infection in barley in order to identify potential targets for resistance breeding. Methods: Utilizing the strength of proteomics in understanding plant-pathogen interactions, we performed an integrative analysis of a published transcriptome dataset with a parallel generated proteome dataset. Therefore, we included two spring barley cultivars with contrasting susceptibilities to Rcc and two fungal isolates causing different levels of RLS symptoms. Results: Interestingly, early responses in the pathogen recognition phase of the host were driven by strong responses differing between isolates. An important enzyme in this process is a xylanase inhibitor, which protected the plant from cell wall degradation by the fungal xylanase. At later time points, the differences were driven by cultivar-specific responses, affecting mostly features contributing to the pathogenesis- and senescence-related pathways or photosynthesis. Discussion: This supports the hypothesis of a hemibiotrophic lifestyle of Rcc, with slight differences in trophism of the two analyzed isolates. The integration of these data modalities highlights a strength of protein-level analysis in understanding plant-pathogen interactions and reveals new features involved in fungal recognition and susceptibility in barley cultivars.

Effect of Bio-Fertilizer Application on Agronomic Traits, Yield, and Nutrient Uptake of Barley (Hordeum vulgare) in Saline Soil.

Under salinity conditions, growth and productivity of grain crops decrease, leading to inhibition and limited absorption of water and elements necessary for plant growth, osmotic imbalance, ionic stress, and oxidative stress. Microorganisms in bio-fertilizers have several mechanisms to provide benefits to crop plants and reduce the harmful effect of salinity. They can be effective in dissolving phosphate, fixing nitrogen, promoting plant growth, and can have a combination of all these qualities. During two successful agricultural seasons, two field experiments were conducted to evaluate the effect of bio-fertilizer applications, including phosphate solubilizing bacteria (PSB), nitrogen fixation bacteria and a mix of phosphate-solubilizing bacteria and nitrogen fixation bacteria with three rates, 50, 75 and 100% NPK, of the recommended dose of minimal fertilizer on agronomic traits, yield and nutrient uptake of barley (Hordeum vulgare) under saline condition in Village 13, Farafra Oasis, New Valley Governorate, Egypt. The results showed that the application of Microbein + 75% NPK recorded the highest values of plant height, spike length, number of spikes/m2, grain yield (Mg ha-1), straw yield (Mg ha-1), biological yield (Mg ha-1), protein content %, nitrogen (N), phosphorus (P), potassium (K) uptakes in grain and straw (kg ha-1), available nitrogen (mg/kg soil), available phosphorus (mg/kg soil), total microbial count of soil, antioxidant activity of soil (AOA), dehydrogenase, nitrogen fixers, and PSB counts. The application of bio-fertilizers led to an increase in plant tolerance to salt stress, plant growth, grain yield, and straw yield, in addition to the application of the bio-fertilizers, which resulted in a 25% saving in the cost of mineral fertilizers used in barley production.

A guide to barley mutants.

BACKGROUND: Mutants have had a fundamental impact upon scientific and applied genetics. They have paved the way for the molecular and genomic era, and most of today's crop plants are derived from breeding programs involving mutagenic treatments. RESULTS: Barley (Hordeum vulgare L.) is one of the most widely grown cereals in the world and has a long history as a crop plant. Barley breeding started more than 100 years ago and large breeding programs have collected and generated a wide range of natural and induced mutants, which often were deposited in genebanks around the world. In recent years, an increased interest in genetic diversity has brought many historic mutants into focus because the collections are regarded as valuable resources for understanding the genetic control of barley biology and barley breeding. The increased interest has been fueled also by recent advances in genomic research, which provided new tools and possibilities to analyze and reveal the genetic diversity of mutant collections. CONCLUSION: Since detailed knowledge about phenotypic characters of the mutants is the key to success of genetic and genomic studies, we here provide a comprehensive description of mostly morphological barley mutants. The review is closely linked to the International Database for Barley Genes and Barley Genetic Stocks ( bgs.nordgen.org ) where further details and additional images of each mutant described in this review can be found.

Barley AGO4 proteins show overlapping functionality with distinct small RNA-binding properties in heterologous complementation.

KEY MESSAGE: Barley AGO4 proteins complement expressional changes of epigenetically regulated genes in Arabidopsis ago4-3 mutant and show a distinct affinity for the 5' terminal nucleotide of small RNAs, demonstrating functional conservation and divergence. The function of Argonaute 4 (AGO4) in Arabidopsis thaliana has been extensively characterized; however, its role in monocots, which have large genomes abundantly supplemented with transposable elements (TEs), remains elusive. The study of barley AGO4 proteins can provide insights into the conserved aspects of RNA-directed DNA methylation (RdDM) and could also have further applications in the field of epigenetics or crop improvement. Bioinformatic analysis of RNA sequencing data identified two active AGO4 genes in barley, HvAGO4a and HvAGO4b. These genes function similar to AtAGO4 in an Arabidopsis heterologous complementation system, primarily binding to 24-nucleotide long small RNAs (sRNAs) and triggering methylation at specific target loci. Like AtAGO4, HvAGO4B exhibits a preference for binding sRNAs with 5' adenine residue, while also accepting 5' guanine, uracil, and cytosine residues. In contrast, HvAGO4A selectively binds only sRNAs with a 5' adenine residue. The diverse binding capacity of barley AGO4 proteins is reflected in TE-derived sRNAs and in their varying abundance. Both barley AGO4 proteins effectively restore the levels of extrachromosomal DNA and transcript abundancy of the heat-activated ONSEN retrotransposon to those observed in wild-type Arabidopsis plants. Our study provides insight into the distinct binding specificities and involvement in TE regulation of barley AGO4 proteins in Arabidopsis by heterologous complementation.

Unravelling the combined impacts of drought and Cu in barley plants - double trouble?

The occurrence of drought in soils, particularly in those contaminated by metals, poses a current threat to crops, as these factors can interact and induce unique stress responses. Therefore, this study mainly focused on understanding the crosstalk between drought and copper (Cu) stress in the physiology of the barley (Hordeum vulgare L.) plant. Using a bifactorial experimental design, seedlings were grown in a natural soil under the following treatments: plants continuously irrigated in uncontaminated soil for 14 days (control); plants continuously irrigated in Cu-contaminated soil (115 mg Cu kg-1) for 14 days (Cu); plants only irrigated during the initials 7 days of growth in uncontaminated soil (drought); plants co-exposed to Cu and drought (combined). After 14 days of growth, the results revealed that drought prevented Cu bioaccumulation in barley roots, which were still severely affected by the metal, both individually and in combination with the water deficit. Furthermore, individual and combined exposure to these stressors resulted in impaired photosynthetic performance in barley plants. Despite the increased activation of enzymatic and non-enzymatic antioxidant defence mechanisms, particularly in the green organs, the plants co-exposed to both stress factors still showed higher oxidative damage, severely impacting biomass production.

Exogenous abscisic acid induces the formation of a suberized barrier to radial oxygen loss in adventitious roots of barley (Hordeum vulgare).

BACKGROUND AND AIMS: Internal root aeration is essential for root growth in waterlogged conditions. Aerenchyma provides a path for oxygen to diffuse to the roots. In most wetland species, including rice, a barrier to radial oxygen loss (ROL) allows more of the oxygen to diffuse to the root tip, enabling root growth into anoxic soil. Most dryland crops, including barley, do not form a root ROL barrier. We previously found that abscisic acid (ABA) signalling is involved in the induction of ROL barrier formation in rice during waterlogging. Although rice typically does not form a tight ROL barrier in roots in aerated conditions, an ROL barrier with suberized exodermis was induced by application of exogenous ABA. Therefore, we hypothesized that ABA application could also trigger root ROL barrier formation with hypodermal suberization in barley. METHODS: Formation of an ROL barrier was examined in roots in different exogenous ABA concentrations and at different time points using cylindrical electrodes and Methylene Blue staining. Additionally, we evaluated root porosity and observed suberin and lignin modification. Suberin, lignin and Casparian strips in the cell walls were observed by histochemical staining. We also evaluated the permeability of the apoplast to a tracer. KEY RESULTS: Application of ABA induced suberization and ROL barrier formation in the adventitious roots of barley. The hypodermis also formed lignin-containing Casparian strips and a barrier to the infiltration of an apoplastic tracer (periodic acid). However, ABA application did not affect root porosity. CONCLUSIONS: Our results show that in artificial conditions, barley can induce the formation of ROL and apoplastic barriers in the outer part of roots if ABA is applied exogenously. The difference in ROL barrier inducibility between barley (an upland species) and rice (a wetland species) might be attributable to differences in ABA signalling in roots in response to waterlogging conditions.

Investigation of the morphological, physiological, biochemical, and catabolic characteristics and gene expression under drought stress in tolerant and sensitive genotypes of wild barley [Hordeum vulgare subsp. spontaneum (K. Koch) Asch. & Graebn.].

BACKGROUND: Barley (H. vulgare L.) is an important cereal crop cultivated across various climates globally. Barley and its ancestor (H. vulgare subsp. spontaneum) are an economically valuable model for genetic research and improvement. Drought, among various abiotic stresses, is a substantial threat to agriculture due to its unpredictable nature and significant impact on crop yield. RESULTS: This study was conducted in both greenhouse and laboratory settings. Prior to the study, wild barley accessions were pre-selected based on their sensitivity or tolerance to drought as determined from fieldwork in the 2020-2021 and 2021-2022 cropping seasons. The effects of three levels of drought stress were evaluated (control, 90-95% field capacity [FC]; mild stress, 50-55% FC; and severe stress, 25-30% FC). Several parameters were assessed, including seedling and root growth, enzymatic activity (CAT, SOD, POD), soluble protein levels, chlorophyll content, carotenoids, abaxial and adaxial stomatal density and dimensions, and relative gene expression of Dhn1, SOD, POD, and CAT. Drought stress significantly increased enzyme activities, especially at 25-30% FC, and more in the tolerant genotype. On the other hand, sensitive genotypes showed a notable increase in stomatal density. Under drought stress, there was a general decline in seedling and root growth, protein content, chlorophyll and carotenoids, and stomatal dimensions. Importantly, gene expression analysis revealed that Dhn1, SOD, POD, and CAT were upregulated under drought, with the highest expression levels observed in the drought-tolerant genotype under severe stress conditions (25-30% FC). CONCLUSIONS: Our investigation highlights the distinct morphological, physiological, biochemical, and gene-expression profiles of drought-resistant and drought-sensitive wild barley genotypes under varying degrees of drought.

Phytochemical analysis, GC-MS characterization and antioxidant activity of Hordeum vulgare seed extracts.

Barley scientifically known as Hordeum vulgare (HV) is a major grain crop. Over the course of time, great interest has been developed in the usage of barley, because of its various pharmacological activities. Current study is designed to determine the chemical constituents of Hordeum vulgare (HV) seed extract by GC-MS technique, and Invitro antioxidant assays i.e. 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH) and 2-azino-bis(3-ethyl benzthiazoline-6-sulfonic acid) (ABTS) methods. GC-MS identified 16 non-polar compounds in the hexane extract of HV plant, which includes carboxylic acid (6.25%), fatty acid (37.5%), carboxylic acid amide derivative of fatty acid (6.25%), triterpinoids (18.75%), fat soluble vitamin (6.25%), phytosterol (6.25%), stigmastanes (6.25%), beta diketones (6.25%), and cycloartenol (6.25%) respectively. The major compound includes Hexadecanoic acid, methyl ester (6.84%), n-Hexadecanoic acid (8.58%), 9,12-Octadecanoic acid (Z,Z)-, Methyl Ester (8.04%), 9,12-Octadecadienoic acid (Z,Z) (57.01%), Lup-20(29)-en-3-one (3.57%), γ-Sitosterol (3.31%). Some constituents such as Lup-20(29)-en-3-one, campesterol and squalene were observed and were not previously reported. Total phenolic and total flavonoid content were determined using spectrophotometric technique and calculated as gallic acid equivalents GAE/g dry weight and rutin equivalent RE/g of dry weight respectively.The highest phenolic content exhibited by the acetone extract of HV seedsi.e. 0.0597 mg GAE/g while the highest flavonoid content exhibited by dichloromethane extract i.e. 0.09 mg RE/g and 0.25 mg QE/g of dry weight respectively. All the extracts showed significant antioxidant activity in DPPH and ABTS cation decolorization assays. Methanol and dichloromethane extract showed the highest DPPH radical scavenging activity i.e. 52.41% and 42.07% at the concentration of 100 mg/ml respectively. Moreover, the IC50 has been determined by the acetone and methanol extract of HV seeds. The high antioxidant activity of its seed extracts has made this plant pharmacologically important. Conclusively, there is a vast scope to further explore the active principals of barley so that more of its pharmacological properties can be identified.

Plasticity of parental CENH3 incorporation into the centromeres in wheat × barley F1 hybrids.

Incorporating the centromere-specific histone H3 protein CENH3 into the centromeric nucleosomes is indispensable for accurate centromere function and balanced chromosome segregation in most eukaryotes, including higher plants. In the cell nuclei of interspecific hybrids, divergent centromeric DNAs cohabit and lead the corresponding parental chromosomes through the mitotic and meiotic cell divisions. Depending on the transmission of the parental chromosomes carrying the CENH3-encoding genes, CENH3 proteins from one or both parents may be present in these hybrids. The incorporation of parental CENH3 proteins into the divergent centromeres and their role in the chromosome elimination process in interspecific hybrids is still poorly understood. Here, we produced wheat × barley F1 hybrids that carried different combinations of barley chromosomes with genes encoding for either one (αCENH3) or both barley CENH3 protein variants (α- and ßCENH3). We generated specific antibodies distinguishing between the wheat CENH3 proteins and barley αCENH3 and applied them together with FISH probes to detect the precise pattern of parental CENH3 deposition into the wheat and barley centromeric nucleosomes. Analysis of somatic and meiotic nuclei of the wheat × barley hybrids revealed the plasticity of the maternal (wheat) CENH3 proteins to become incorporated into the paternal (barley) centromeric nucleosomes. However, no evidence for paternal CENH3 plasticity was detected in this study. The significance of the unilateral centromere plasticity and possible patterns of CENH3 incorporation into centromeres in interspecific hybrids are discussed.

Contrasting cytosolic glutathione redox dynamics under abiotic and biotic stress in barley as revealed by the biosensor Grx1-roGFP2.

Barley is a staple crop of major global importance and relatively resilient to a wide range of stress factors in the field. Transgenic reporter lines to investigate physiological parameters during stress treatments remain scarce. We generated and characterized transgenic homozygous barley lines (cv. Golden Promise Fast) expressing the genetically encoded biosensor Grx1-roGFP2, which indicates the redox potential of the major antioxidant glutathione in the cytosol. Our results demonstrated functionality of the sensor in living barley plants. We determined the glutathione redox potential (EGSH) of the cytosol to be in the range of -308 mV to -320 mV. EGSH was robust against a combined NaCl (150 mM) and water deficit treatment (-0.8 MPa) but responded with oxidation to infiltration with the phytotoxic secretome of the necrotrophic fungus Botrytis cinerea. The generated reporter lines are a novel resource to study biotic and abiotic stress resilience in barley, pinpointing that even severe abiotic stress leading to a growth delay does not automatically induce cytosolic EGSH oxidation, while necrotrophic pathogens can undermine this robustness.

Genome-wide analysis of FRF gene family and functional identification of HvFRF9 under drought stress in barley.

FHY3 and its homologous protein FAR1 are the founding members of FRS family. They exhibited diverse and powerful physiological functions during evolution, and participated in the response to multiple abiotic stresses. FRF genes are considered to be truncated FRS family proteins. They competed with FRS for DNA binding sites to regulate gene expression. However, only few studies are available on FRF genes in plants participating in the regulation of abiotic stress. With wide adaptability and high stress-resistance, barley is an excellent candidate for the identification of stress-resistance-related genes. In this study, 22 HvFRFs were detected in barley using bioinformatic analysis from whole genome. According to evolution and conserved motif analysis, the 22 HvFRFs could be divided into subfamilies I and II. Most promoters of subfamily I members contained abscisic acid and methyl jasmonate response elements; however, a large number promoters of subfamily II contained gibberellin and salicylic acid response elements. HvFRF9, one of the members of subfamily II, exhibited a expression advantage in different tissues, and it was most significantly upregulated under drought stress. In-situ PCR revealed that HvFRF9 is mainly expressed in the root epidermal cells, as well as xylem and phloem of roots and leaves, indicating that HvFRF9 may be related to absorption and transportation of water and nutrients. The results of subcellular localization indicated that HvFRF9 was mainly expressed in the nuclei of tobacco epidermal cells and protoplast of arabidopsis. Further, transgenic arabidopsis plants with HvFRF9 overexpression were generated to verify the role of HvFRF9 in drought resistance. Under drought stress, leaf chlorosis and wilting, MDA and O2 - contents were significantly lower, meanwhile, fresh weight, root length, PRO content, and SOD, CAT and POD activities were significantly higher in HvFRF9-overexpressing arabidopsis plants than in wild-type plants. Therefore, overexpression of HvFRF9 could significantly enhance the drought resistance in arabidopsis. These results suggested that HvFRF9 may play a key role in drought resistance in barley by increasing the absorption and transportation of water and the activity of antioxidant enzymes. This study provided a theoretical basis for drought resistance in barley and provided new genes for drought resistance breeding.

Determination of the Allelic Composition of the sdw1/denso (HvGA20ox2), uzu1 (HvBRI1) and ari-e (HvDep1) Genes in Spring Barley Accessions from the VIR Collection.

The lodging of barley significantly limits its potential yield, leads to the deterioration of grain quality, and complicates mechanized harvesting. More than 30 dwarfness and semi-dwarfness genes and loci are known for barley, and their involvement in breeding can solve the problem of lodging. The most common dwarfing alleles are of the genes sdw1/denso (HvGA20ox2), uzu1 (HvBRI1), and ari-e (HvDep1). The aim of this study was the design of dCAPS markers for the sdw1.c and ari-e.GP alleles and the molecular screening of barley accessions from the VIR collection for identifying these and other dwarfing alleles commonly used in breeding. Two dCAPS markers have been developed to identify the sdw1.c allele of the HvGA20ox2 gene and ari-e.GP of HvDep1. These dCAPS markers and two known from the literature CAPS and dCAPS markers of the alleles sdw1.a/sdw1.e, sdw1.c, sdw1.d, and uzu1.a were used in the molecular screening of 32 height-contrasting barley accessions. This made it possible to identify the accessions with alleles sdw1.a/sdw1.e, sdw1.c, and sdw1.d of the HvGA20ox2 gene, as well as accessions with a combination of sdw1.c and uzu1.a alleles of the genes HvGA20ox2 and HvBRI1. A comparison of the results of genotyping and phenotyping showed that the presence of dwarfing alleles in all genotypes determines high or medium lodging resistance regardless of the influence of weather conditions. Twelve accessions were found to contain the new allele sdw1.ins of the HvGA20ox2 gene, which differs from the known allele sdw1.c by a larger size of PCR products. It is characterized by the Thalos_2 transposon insertion; the subsequent GTTA insertion, common with the sdw1.c allele; and by a single-nucleotide G→A substitution at the 165 position.

Anatomical insights into the vascular lay-out of the barley rachis: implications for transport and spikelet connection.

BACKGROUND AND AIMS: Vascular patterning is intimately related to plant form and function. Here, using barley (Hordeum vulgare) as a model, we studied the vascular anatomy of the spike-type inflorescence. The main aim of the present work was to clarify the relationship between rachis (spike axis) vasculature and spike size, define vascular dynamics, the implications for transport capacity and its interaction with the spikelets. METHODS: We employed serial transversal internode sections to determine the internode area, vascular area, and vein number along the rachis of several barley lines. KEY RESULTS: Internode area and total vascular area show a clear positive correlation with spike size, whereas vascular number is only weakly correlated. While the lateral periphery of the rachis contains large mature veins of constant size, the central part is occupied by small immature veins. Spikelet-derived veins entering the rachis often merge with the immature rachis veins but never merge with the mature veins. An increase in floret fertility through the conversion of a two-rowed barley into an isogenic six-rowed line, as well as a decrease in floret fertility due to enhanced pre-anthesis tip degeneration caused by the mutation tip sterile 2.b (tst2.b) significantly affected vein size, but had limited to no effects on vein number or internode area. CONCLUSIONS: The rachis vasculature is the result of a two-step process involving an initial layoutfollowed by size adjustment according to floret fertility/spike size. The restriction of large mature vessels to the periphery and that of small immature vessels to the center of the rachis suggests that long distance transport and local supply to spikelets are spatially separated processes.The identification of spikelet-derived veins entering the rachis without fusing with its vasculature indicates that a vascular continuity between rachis and spikelets may be non-essential.

HOMEOBOX2, the paralog of SIX-ROWED SPIKE1/HOMEOBOX1, is dispensable for barley spikelet development.

The HD-ZIP class I transcription factor, HvHOX1 (Homeobox 1) or VRS1 (Vulgare Row-type Spike 1 or Six-rowed Spike 1), regulates lateral spikelet fertility in barley (Hordeum vulgare L.). It was shown that HvHOX1 has a high expression only in lateral spikelets, while its paralog HvHOX2 was found to be expressed in different plant organs. Yet, the mechanistic function of HvHOX1 and HvHOX2 during spikelet development is still fragmentary. Here, we show that compared to HvHOX1, HvHOX2 is more highly conserved across different barley genotypes and Hordeum species, hinting at a possibly vital but still unclarified biological role. Using bimolecular fluorescence complementation, DNA-binding, and transactivation assays, we validate that HvHOX1 and HvHOX2 are bona fide transcriptional activators that may potentially heterodimerize. Accordingly, both genes exhibit similar spatiotemporal expression patterns during spike development and growth, albeit their mRNA levels differ quantitatively. We show that HvHOX1 delays the lateral spikelet meristem differentiation and affects fertility by aborting the reproductive organs. Interestingly, the ancestral relationship of these genes inferred from their co-expressed gene networks suggested that HvHOX1 and HvHOX2 might play a similar role during barley spikelet development. However, CRISPR-derived mutants of HvHOX1 and HvHOX2 demonstrated the suppressive role of HvHOX1 on lateral spikelets, while the loss of HvHOX2 does not influence spikelet development. Collectively, our study shows that through the suppression of reproductive organs, lateral spikelet fertility is regulated by HvHOX1, whereas HvHOX2 is dispensable for spikelet development in barley.

Differential physiological and production responses of C3 and C4 crops to climate factor interactions.

This study examined the effect of the interactions of key factors associated with predicted climate change (increased temperature, and drought) and elevated CO2 concentration on C3 and C4 crop representatives, barley and sorghum. The effect of two levels of atmospheric CO2 concentration (400 and 800 ppm), three levels of temperature regime (21/7, 26/12 and 33/19°C) and two regimes of water availability (simulation of drought by gradual reduction of irrigation and well-watered control) in all combinations was investigated in a pot experiment within growth chambers for barley variety Bojos and sorghum variety Ruby. Due to differences in photosynthetic metabolism in C3 barley and C4 sorghum, leading to different responses to elevated CO2 concentration, we hypothesized mitigation of the negative drought impact in barley under elevated CO2 concentration and, conversely, improved performance of sorghum at high temperatures. The results demonstrate the decoupling of photosynthetic CO2 assimilation and production parameters in sorghum. High temperatures and elevated CO2 concentration resulted in a significant increase in sorghum above- and below-ground biomass under sufficient water availability despite the enhanced sensitivity of photosynthesis to high temperatures. However, the negative effect of drought is amplified by the effect of high temperature, similarly for biomass and photosynthetic rates. Sorghum also showed a mitigating effect of elevated CO2 concentration on the negative drought impact, particularly in reducing the decrease of relative water content in leaves. In barley, no significant factor interactions were observed, indicating the absence of mitigating the negative drought effects by elevated CO2 concentration. These complex interactions imply that, unlike barley, sorghum can be predicted to have a much higher variability in response to climate change. However, under conditions combining elevated CO2 concentration, high temperature, and sufficient water availability, the outperforming of C4 crops can be expected. On the contrary, the C3 crops can be expected to perform even better under drought conditions when accompanied by lower temperatures.

Core promoterome of barley embryo.

Precise localization and dissection of gene promoters are key to understanding transcriptional gene regulation and to successful bioengineering applications. The core RNA polymerase II initiation machinery is highly conserved among eukaryotes, leading to a general expectation of equivalent underlying mechanisms. Still, less is known about promoters in the plant kingdom. In this study, we employed cap analysis of gene expression (CAGE) at three embryonic developmental stages in barley to accurately map, annotate, and quantify transcription initiation events. Unsupervised discovery of de novo sequence clusters grouped promoters based on characteristic initiator and position-specific core-promoter motifs. This grouping was complemented by the annotation of transcription factor binding site (TFBS) motifs. Integration with genome-wide epigenomic data sets and gene ontology (GO) enrichment analysis further delineated the chromatin environments and functional roles of genes associated with distinct promoter categories. The TATA-box presence governs all features explored, supporting the general model of two separate genomic regulatory environments. We describe the extent and implications of alternative transcription initiation events, including those that are specific to developmental stages, which can affect the protein sequence or the presence of regions that regulate translation. The generated promoterome dataset provides a valuable genomic resource for enhancing the functional annotation of the barley genome. It also offers insights into the transcriptional regulation of individual genes and presents opportunities for the informed manipulation of promoter architecture, with the aim of enhancing traits of agronomic importance.

Isolation and identification of a new Bacillus glycinifermentans strain from date palm rhizosphere and its effect on barley seeds under heavy metal stress.

Soil contamination by heavy metals is one of the major problems that adversely decrease plant growth and biomass production. Inoculation with the plant growth-promoting rhizobacteria (PGPR) can attenuate the toxicity of heavy metals and enhancing the plant growth. In this study, we evaluated the potential of a novel extremotolerant strain (IS-2 T) isolated from date palm rhizosphere to improve barley seedling growth under heavy metal stress. The species-level identification was carried out using morphological and biochemical methods combined with whole genome sequencing. The bacterial strain was then used in vitro for inoculating Hordeum vulgare L. exposed to three different Cr, Zn, and Ni concentrations (0.5, 1, and 2 mM) in petri dishes and different morphological parameters were assessed. The strain was identified as Bacillus glycinifermentans species. This strain showed high tolerance to pH (6-11), salt stress (0.2-2 M), and heavy metals. Indeed, the minimum inhibitory concentrations at which bacterium was unable to grow were 4 mM for nickel, 3 mM for zinc, more than 8 mM for copper, and 40 mM for chromium, respectively. It was observed that inoculation of Hordeum vulgare L. under metal stress conditions with Bacillus glycinifermentans IS-2 T stain improved considerably the growth parameters. The capacity of the IS-2 T strain to withstand a range of abiotic stresses and improve barley seedling development under lab conditions makes it a promising candidate for use as a PGPR in zinc, nickel, copper, and chromium bioremediation.