Hydrogen sulfide alleviates cadmium stress in germinating carrot seeds by promoting the accumulation of proline.

Carrot (Daucus carota L.), a widely cultivated economically vegetable from the Apiaceae family, is grown globally. However, carrots can be adversely impacted by cadmium (Cd) pollution in the soil due to its propensity to accumulate in the fleshy root, thus impeding carrot growth and posing health hazards to consumers. Given the potential of hydrogen sulfide (H2S) to improve plant resistance against Cd stress, we treated germinating carrot seeds with varying concentrations of sodium hydrosulfide (NaHS), aiming to alleviate the toxic impacts of Cd stress on carrot seed germination. The results revealed that carrot seeds treated with a concentration of 0.25 mM NaHS displayed better seed germination-associated characteristics compared to seeds treated with NaHS concentrations of 0.1 mM and 0.5 mM. Further investigation revealed a rise in the expression levels of L-cysteine desulfhydrase and D-cysteine desulfhydrase, along with enhanced activity of L-cysteine desulfhydrase and D-cysteine desulfhydrase among the NaHS treatment group, thereby leading to H2S accumulation. Moreover, NaHS treatment triggered the expression of pyrroline-5-carboxylate synthase and pyrroline-5-carboxylate reductase and promoted the accumulation of endogenous proline, while the contents of soluble sugar and soluble protein increased correspondingly. Interestingly, since the application of exogenous proline did not influence the accumulation of endogenous H2S, suggesting that H2S served as the upstream regulator of proline. Histochemical staining and biochemical indices revealed that NaHS treatment led to elevated antioxidant enzyme activity, alongside a suppression of superoxide anion and hydrogen peroxide generation. Furthermore, high performance liquid chromatography analysis revealed that NaHS treatment reduced Cd2+ uptake, thereby promoting germination rate, seed vitality, and hypocotyl length of carrot seeds under Cd stress. Overall, our findings shed light on the application of NaHS to enhance carrot resistance against Cd stress and lay a foundation for exploring the regulatory role of H2S in plants responding to Cd stress.

Lipid profiling reveals Leymus Chinensis root insensitivity to Ca limitation.

BACKGROUND: Leymus chinensis (L. chinensis) is a perennial native forage grass widely distributed in the steppe of Inner Mongolia as the dominant species. Calcium (Ca) is an essential mineral element important for plant adaptation to the growth environment. Ca limitation was previously shown to strongly inhibit Arabidopsis (Arabidopsis thaliana) seedling growth and disrupt plasma membrane stability and selectivity, increasing fluid-phase-based endocytosis and contents of all major membrane lipids. RESULTS: In this study, we investigated the significance of Ca for L. chinensis growth and membrane stability relative to Arabidopsis. Our results showed that Ca limitation did not affect L. chinensis seedling growth and endocytosis in roots. Moreover, the plasma membrane maintained high selectivity. The lipid phosphatidylcholine (PC): phosphatidylethanolamine (PE) ratio, an indicator of the membrane stability, was five times higher in L. chinensis than in Arabidopsis. Furthermore, in L. chinensis, Ca limitation did not affect the content of any major lipid types, decreased malondialdehyde (MDA) content, and increased superoxide dismutase (SOD) activity, showing an opposite pattern to that in Arabidopsis. L. chinensis roots accumulated higher contents of PC, phosphatidylinositol (PI), monogalactosyldiacylglycerol (MGDG), phosphatidylglycerol (PG), cardiolipin (CL), digalactosyldiacylglycerol (DGDG), and lysophosphatidylcholine (LPC) but less phosphatidylethanolamine (PE), diacylglycerol (DAG), triacylglycerolv (TAG), phosphatidylserine (PS), lysobisphosphatidic acids (LPAs), lysophosphatidylethanolamine (LPE), and lysophosphatidylserine (LPS) than Arabidopsis roots. Moreover, we detected 31 and 66 unique lipids in L. chinensis and Arabidopsis, respectively. CONCLUSIONS: This study revealed that L. chinensis roots have unique membrane lipid composition that was not sensitive to Ca limitation, which might contribute to the wider natural distribution of this species.

Investigating the effectiveness of LED lighting in the production of rich sprouts for food purposes.

In recent times, there has been a surge in interest in the impact of diet and physical activity on human health, with the goal of expanding lifespan and enhancing the quality of life. This has Light-emitting diode (LED) to interventions centered on incorporating healthy foods, including fresh sprouts, which are rich in antioxidant compounds and beneficial phytonutrients for human consumption. Various factors, such as temperature, nutritional solution, and types of light quality and intensity, can influence the nutritional value of sprouts. This study evaluates the impact of LED light with red-blue-ultraviolet (6:3:1; R:B:UV) and three levels of intensity (control, 120, and 150 µmol/m2s-1) on five different sprout species, namely wheat, barley, mung bean, alfalfa, and soybean, after seven days of germination. The research investigates the effects on various parameters, including photosynthetic pigments (chlorophylls a, b, total), carotenoid, activities of antioxidant enzymes such as catalase, superoxide dismutase, and soluble proteins, soluble sugars, starch, vitamin C, and element content such as potassium, iron, and phosphorus. The results indicate that the LED treatments and increasing light intensity significantly improve the physiological and antioxidant properties of edible sprouts, with the 150 µmol/m2s-1 treatment producing the most beneficial outcomes. Additionally, increasing light intensity reduces starch content while enhancing the content of photosynthetic pigments, soluble carbohydrates, vitamin C, element concentration, antioxidant enzymes, and soluble proteins. Among the five species of edible sprouts, barley had the highest content of photosynthetic pigments, while soybean and mung beans had the lowest content. Mung beans and alfalfa had the highest and lowest concentrations of potassium and iron, respectively. In terms of phosphorus concentration, soybean and barley sprouts showed the highest and lowest concentrations, respectively.

Transcriptome analysis of barley (Hordeum vulgare L.) under waterlogging stress, and overexpression of the HvADH4 gene confers waterlogging tolerance in transgenic Arabidopsis.

BACKGROUND: Waterlogging is one of the major abiotic stresses in barley and greatly reduces grain yield and quality. To explore the mechanism controlling waterlogging tolerance in barley, physiological, anatomical and transcriptional analyses were performed in two contrasting barley varieties, viz. Franklin (susceptible) and TX9425 (tolerant). RESULTS: Compared to Franklin, TX9425 had more adventitious roots and aerenchymas and higher antioxidant enzyme activities. A total of 3064 and 5693 differentially expressed genes (DEGs) were identified in TX9425 after 24 h and 72 h of waterlogging treatment, respectively, while 2297 and 8462 DEGs were identified in Franklin. The results suggested that TX9425 was less affected by waterlogging stress after 72 h of treatment. The DEGs were enriched mainly in energy metabolism, hormone regulation, reactive oxygen species (ROS) scavenging, and cell wall-modifying enzymes. Alcohol dehydrogenase (ADH) plays an important role in response to waterlogging stress. We found that HvADH4 was significantly upregulated under waterlogging stress in TX9425. Transgenic Arabidopsis overexpressing HvADH4 displayed higher activity of antioxidant enzymes and was more tolerant to waterlogging than the wild type (WT). CONCLUSIONS: The current results provide valuable information that will be of great value for the exploration of new candidate genes for molecular breeding of waterlogging tolerance in barley.

Genomic and Pathogenic Diversity of Barley Yellow Mosaic Virus and Barley Mild Mosaic Virus Isolates in Fields of China and Their Compatibility with Resistance Genes of Cultivated Barley.

Plant viruses transmitted by the soilborne plasmodiophorid Polymyxa graminis constantly threaten global production of cereal crops. Although the yellow mosaic virus disease of barley has been known to be present for a long time in China, the understanding of the diversity of the viral pathogens and their interactions with host resistance remains limited. In this study, we conducted a nationwide survey of P. graminis and the barley yellow mosaic virus (BaYMV) and barley mild mosaic virus (BaMMV) it transmits, followed by genomic and pathogenic diversity analyses of both viruses. BaYMV and BaMMV were found exclusively in the region downstream of the Yangtze River, despite the national distribution of its transmission vector P. graminis. Analysis of the genomic variations of BaYMV and BaMMV revealed an elevated rate of nonsynonymous substitutions in the viral genome-linked protein (VPg), in which most substitutions were located in its interaction surface with the host eukaryotic translation initiation factor 4E (eIF4E). VPg sequence diversity was associated with the divergence in virus pathogenicity that was identified through multiple field trials. The majority of the resistance genes, including the widely applied rym4 and rym5 (alleles of eIF4E), as well as the combination of rym1/11 and rym5, are not sufficient to protect cultivated barley against viruses in China. Collectively, these results provide insights into virulence specificity and interaction mode with host resistance in cultivated barley, which has significant implications in breeding for the broad-spectrum resistance barley varieties.

Genome-wide association scan and transcriptome analysis reveal candidate genes for waterlogging tolerance in cultivated barley.

Waterlogging is the primary abiotic factor that destabilizes the yield and quality of barley (Hordeum vulgare L.). However, the genetic basis of waterlogging tolerance remains poorly understood. In this study, we conducted a genome-wide association study (GWAS) by involving 106,131 single-nucleotide polymorphisms (SNPs) with a waterlogging score (WLS) of 250 barley accessions in two years. Out of 72 SNPs that were found to be associated with WLS, 34 were detected in at least two environments. We further performed the transcriptome analysis in root samples from TX9425 (waterlogging tolerant) and Franklin (waterlogging sensitive), resulting in the identification of 5,693 and 8,462 differentially expressed genes (DEGs) in these genotypes, respectively. The identified DEGs included various transcription factor (TF) genes, primarily including AP2/ERF, bZIP and MYB. By combining GWAS and RNA-seq, we identified 27 candidate genes associated with waterlogging, of which three TFs (HvDnaJ, HvMADS and HvERF1) were detected in multiple treatments. Moreover, by overexpressing barley HvERF1 in Arabidopsis, the transgenic lines were detected with enhanced waterlogging tolerance. Altogether, our results provide new insights into the genetic mechanisms of waterlogging, which have implications in the molecular breeding of waterlogging-tolerant barley varieties.

Overexpression of Barley Transcription Factor HvERF2.11 in Arabidopsis Enhances Plant Waterlogging Tolerance.

Waterlogging stress significantly affects the growth, development, and productivity of crop plants. However, manipulation of gene expression to enhance waterlogging tolerance is very limited. In this study, we identified an ethylene-responsive factor from barley, which was strongly induced by waterlogging stress. This transcription factor named HvERF2.11 was 1158 bp in length and encoded 385 amino acids, and mainly expressed in the adventitious root and seminal root. Overexpression of HvERF2.11 in Arabidopsis led to enhanced tolerance to waterlogging stress. Further analysis of the transgenic plants showed that the expression of AtSOD1, AtPOD1 and AtACO1 increased rapidly, while the same genes did not do so in non-transgenic plants, under waterlogging stress. Activities of antioxidant enzymes and alcohol dehydrogenase (ADH) were also significantly higher in the transgenic plants than in the non-transgenic plants under waterlogging stress. Therefore, these results indicate that HvERF2.11 plays a positive regulatory role in plant waterlogging tolerance through regulation of waterlogging-related genes, improving antioxidant and ADH enzymes activities.

Bulked segregant RNA-sequencing (BSR-seq) identified a novel rare allele of eIF4E effective against multiple isolates of BaYMV/BaMMV.

KEY MESSAGE: A novel rare allele of the barley host factor gene eIF4E for BaMMV/BaYMV infection was identified in an Iranian landrace that showed broad resistance to barley yellow mosaic virus disease, and molecular markers facilitating efficient selection were developed. The soil-borne yellow mosaic virus disease caused by different strains of barley yellow mosaic virus (BaYMV) and barley mild mosaic virus (BaMMV) is a major threat to winter barley (Hordeum vulgare) production in Europe and East Asia. However, the exploration of resistant germplasm or casual genes for barley breeding is rather limited in relation to the rapid diversification of viral strains. Here, we identified an Iranian barley landrace 'HOR3298,' which represented complete resistance to BaYMV and BaMMV. In contrast to rym4 and rym5, which act as the predominant source in Europe and East Asia for breeding resistant cultivars over decades and which have been overcome by several virulent isolates, this landrace showed broad-spectrum resistance to multiple isolates of BaYMV/BaMMV in the fields of Germany and China. By employment of bulked segregant RNA sequencing, test for allelism, and haplotype analysis, a recessive resistance gene in 'HOR3298' was genetically mapped coincident with the host factor eukaryotic translation initiation factor 4E (eIF4E, causal gene of rym4 and rym5). The eIF4EHOR3298 allele encoded for a novel haplotype that contained an exclusive nucleotide mutation (G565A) in the coding sequence. The easily handled markers were developed based on the exclusively rare variation, providing precise selection of this allele. Thus, this work provided a novel reliable resistance source and the feasible marker-assisted selection assays that can be used in breeding for barley yellow mosaic virus disease resistance in cultivated barley.

Elucidating the hypoxic stress response in barley (Hordeum vulgare L.) during waterlogging: A proteomics approach.

Waterlogging is one of the major abiotic stresses that affects barley production and yield quality. Proteomics techniques have been widely utilized to explore the mechanisms involved in the responses to abiotic stress. In this study, two barley genotypes with contrasting responses to waterlogging stress were analyzed with proteomic technology. The waterlogging treatment caused a greater reduction in biomass and photosynthetic performance in the waterlogging-sensitive genotype TF57 than that in the waterlogging-tolerant genotype TF58. Under waterlogging stress, 30, 30, 20 and 20 differentially expressed proteins were identified through tandem mass spectrometry analysis in the leaves, adventitious roots, nodal roots and seminal roots, respectively. Among these proteins, photosynthesis-, metabolism- and energy-related proteins were differentially expressed in the leaves, with oxygen-evolving enhancer protein 1, ATP synthase subunit and heat shock protein 70 being up-regulated in TF58. Pyruvate decarboxylase (PDC), 1-amino cyclopropane 1-carboxylic acid oxidase (ACO), glutamine synthetase (GS), glutathione S-transferases (GST) and beta-1, 3-glucanase in adventitious, nodal and seminal roots were more abundant in TF58 than those in TF57 under waterlogging stress. Ten representative genes were selected for validation by qRT-PCR in different genotypes with known waterlogging tolerance, and the expression levels of three candidate genes (PDC, ACO and GST) increased in the roots of all genotypes in response to the waterlogging stress. These three genes might play a significant role in the adaptation process of barley under waterlogging stress. The current results partially determined the mechanisms of waterlogging tolerance and provided valuable information for the breeding of barley with enhanced tolerance to waterlogging.

A genome-wide analysis of the ASYMMETRIC LEAVES2/LATERAL ORGAN BOUNDARIES (AS2/LOB) gene family in barley (Hordeum vulgare L.).

ASYMMETRIC LEAVES2/LATERAL ORGAN BOUNDARIES (AS2/LOB) genes are a family of plant specific transcription factors, which play an important role in the regulation of plant lateral organ development and metabolism. However, a genome-wide analysis of the AS2/LOB gene family is still not available for barley. In the present study, 24 AS2-like (ASL)/LOB domain (LBD) genes were identified based on the barley (Hordeum vulgare L.) genome sequence. A phylogenetic tree of ASL/LBD proteins from barley, Arabidopsis, maize, and rice was constructed. The ASL/LBD genes were classified into two classes, class I and class II, which were divided into five and two subgroups, respectively. Genes homologous in barley and Arabidopsis were analyzed. In addition, the structure and chromosomal locations of the genes were analyzed. Expression profiles indicated that barley HvASL/LBD genes exhibit a variety of expression patterns, suggesting that they are involved in various aspects of physiological and developmental processes. This genome-wide analysis of the barley AS2/LOB gene family contributes to our understanding of the functions of the AS2/LOB gene family.

Genome-Wide Analysis of APETALA2/Ethylene-Responsive Factor (AP2/ERF) Gene Family in Barley (Hordeum vulgare L.).

APETALA2/Ethylene-Responsive Factor (AP2/ERF) gene family is plant specific transcription factor. It plays critical roles in development process, tolerance to biotic and abiotic stresses, and responses to plant hormones. However, limited data are available on the contributions of AP2/ERF gene family in barley (Hordeum vulgare L.). In the present study, 121 HvAP2/ERF genes in barley were identified by using bioinformatics methods. A total of 118 HvAP2/ERF (97.5%) genes were located on seven chromosomes. According to phylogenetic classification of AP2/ERF family in Arabidopsis, HvAP2/ERF proteins were divided into AP2 (APETALA2), RAV (Related to ABI3/VP), DREB (dehydration responsive element binding), ERF (ethylene responsive factors) and soloist sub families. The analysis of duplication events indicated that tandem repeat and segmental duplication contributed to the expansion of the AP2/ERF family in barley. HvDREB1s/2s genes displayed various expression patterns under abiotic stress and phytohormone. Taken together, the data generated in this study will be useful for genome-wide analysis to determine the precise role of the HvAP2/ERF gene during barley development, abiotic stress and phytohormone responses with the ultimate goal of improving crop production.

Comparative Proteomic Analysis of Two Barley Cultivars (Hordeum vulgare L.) with Contrasting Grain Protein Content.

Grain protein contents (GPCs) of barley seeds are significantly different between feed and malting barley cultivars. However, there is still no insight into the proteomic analysis of seed proteins between feed and malting barley cultivars. Also, the genetic control of barley GPC is still unclear. GPCs were measured between mature grains of Yangsimai 3 and Naso Nijo. A proteome profiling of differentially expressed protein was established by using a combination of 2-DE and tandem mass spectrometry. In total, 502 reproducible protein spots in barley seed proteome were detected with a pH range of 4-7 and 6-11, among these 41 protein spots (8.17%) were detected differentially expressed between Yangsimai 3 and Naso Nijo. Thirty-four protein spots corresponding to 23 different proteins were identified, which were grouped into eight categories, including stress, protein degradation and post-translational modification, development, cell, signaling, glycolysis, starch metabolism, and other functions. Among the identified proteins, enolase (spot 274) and small subunit of ADP-glucose pyrophosphorylase (spot 271) are exclusively expressed in barley Yangsimai 3, which may be involved in regulating seed protein expression. In addition, malting quality is characterized by an accumulation of serpin protein, Alpha-amylase/trypsin inhibitor CMb and Alpha-amylase inhibitor BDAI-1. Most noticeably, globulin, an important storage protein in barley seed, undergoes post-translational processing in both cultivars, and also displays different expression patterns.