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Hulless barley is a cold-resistant crop widely planted in the northwest plateau of China. It is also the main food crop in this region. Phosphorus (P), as one of the important essential nutrient elements, regulates plant growth and defense. This study aimed to analyze the development and related molecular mechanisms of hulless barley under P deficiency and explore the regulatory genes so as to provide a basis for subsequent molecular breeding research. Transcriptome analysis was performed on the root and leaf samples of hulless barley cultured with different concentrations of KH2PO4 (1 mM and 10 μM) Hoagland solution. A total of 46,439 genes were finally obtained by the combined analysis of leaf and root samples. Among them, 325 and 453 genes had more than twofold differences in expression. These differentially expressed genes (DEGs) mainly participated in the abiotic stress biosynthetic process through Gene Ontology prediction. Moreover, the Kyoto Encyclopedia of Genes and Genomes showed that DEGs were mainly involved in photosynthesis, plant hormone signal transduction, glycolysis, phenylpropanoid biosynthesis, and synthesis of metabolites. These pathways also appeared in other abiotic stresses. Plants initiated multiple hormone synergistic regulatory mechanisms to maintain growth under P-deficient conditions. Transcription factors (TFs) also proved these predictions. The enrichment of ARR-B TFs, which positively regulated the phosphorelay-mediated cytokinin signal transduction, and some other TFs (AP2, GRAS, and ARF) was related to plant hormone regulation. Some DEGs showed different values in their FPKM (fragment per kilobase of transcript per million mapped reads), but the expression trends of genes responding to stress and phosphorylation remained highly consistent. Therefore, in the case of P deficiency, the first response of plants was the expression of stress-related genes. The effects of this stress on plant metabolites need to be further studied to improve the relevant regulatory mechanisms so as to further understand the importance of P in the development and stress resistance of hulless barley.

Leaf stripe is a common, but major infectious disease of barley, severely affecting the yield and quality. However, only a few genes have been identified by conventional gene mapping. Gene family analysis has become a fast and efficient strategy for gene discovery. Studies demonstrated that Argonaute (AGO) proteins play an important role in plant disease resistance. Thus, we obtained nine HvAGO genes via mRNA sequencing before and after a Pyrenophora graminea infection of a disease-resistant variety "Kunlun 14" and a susceptible variety "Z1141". We analysed the physicochemical characteristics, gene structures, and motifs of the HvAGO gene sequences and found that these proteins were divided into four clusters by evolutionary distance. There was high consistency in the number of exons, size, and the number and type of motifs in the different clusters. Based on protein phylogenetics, they could be divided into three branches. A collinearity analysis of Tibetan hull-less barley and Arabidopsis thaliana, rice, and maize showed that four genes were collinear with respect to the other three species. The qRT-PCR showed the expression levels of HvAGO1, HvAGO2 and HvAGO4 were significantly increased after infection with Pyrenophora graminea. These three members of the AGO gene family are, thus, speculated to play an important role in barley leaf stripe resistance. The results provide reference for the application of HvAGO genes in the leaf stripe control and the exploration of disease resistance genes in other crops.

To investigate the role of the HvnAnt2 gene in the formation of different qingke barley grain colours, HvnAnt2 was isolated from the leaves of the White 91-97-3 (white), Blue qingke (blue), Kunlun 17 (black), and Purple qingke (purple). The HvnAnt2 gene encodes a hydrophilic unstable protein consisting of 561 amino acids, without a transmembrane structure and without a signal peptide, with one bHLH-MYC_N and one HLH domain at amino acids 22-204 and 387-436, respectively. The HvnAnt2 of qingke barley was most closely related to Hordeum vulgare and most distantly related to Triticum monococcum; it was mainly related to light responsiveness and methyl jasmonate responsiveness. The Ant2 gene was highly expressed in Kunlun 17 and Purple qingke barley grains during the later stage of development. The protein interaction prediction showed that flavonoid 3'-monooxygenase, anthocyanin biosynthesis gene regulators, and key enzymes in folate metabolism interacted with the Ant2 protein. This study provides a reference for further analysis of the Ant2 gene in the anthocyanin synthesis pathways of qingke barley with different grain colours. [ABSTRACT FROM AUTHOR]

Hulless barley (Hordeum vulgare L. var. nudum Hook. f.), belonging to the genus Gramineae, has high and steady output and thus considered as a principal food crop by Tibetan people. Hulless barley grain can be used for food, brewing, and functional health product development, while its straw serves as an essential supplementary forage and is a crucial cereal crop. Lodging can reduce the yield and quality of barley grain and straw, and it hinders mechanical harvesting. It is a significant factor affecting high and stable yields of barley. Unlike other Poaceae plants (such as rice, wheat), hulless barley is mainly grown in high-altitude regions, where it is susceptible to low temperatures, strong winds, and heavy rainfall. As a result, its stem lodging resistance is relatively weak, making it prone to lodging during the growth period. In this study, we observed that the lignin concentration and the contents of lignin monomers (H, S, and G), and neutral detergent fibre of the lodging-resistant variety Kunlun14 were substantially greater than those of the lodging-sensitive variety Menyuanlianglan. We performed the weighted gene co-expression network analysis (WGCNA) and Short Time-series Expression Miner (STEM) analysis of both the lodging-resistant and lodging-sensitive varieties. Through transcriptome sequencing analysis at different developmental stages, combined with the previously annotated genes related to lodging resistance, a total of 72 DEGs were identified. Among these DEGs, 17 genes were related to lignin, cellulose, and hemicellulose synthesis or regulation, including five transcription factors about NAC, MYB and WRKY. Our results provide a basis for further exploring the molecular mechanism of stem lodging resistance in hulless barley and provide valuable gene resources for stem lodging resistance molecular breeding. [ABSTRACT FROM AUTHOR]

To explore the role of WRKY transcription factors (TFs) in the resistance process of Qingke (Hordeum vulgare L. var. nudum Hook. f.), leaves of the leaf stripe disease-resistant variety Kunlun 14 and the susceptible variety Z1141 were sequenced by transcriptome sequencing (RNA-seq). A differentially expressed gene HvnWKRY1 was identified, and its disease-resistance function was preliminarily analysed. The result showed that the open reading frame (ORF) of the gene was 1 062 bp and encoded 354 amino acids. It contained the conserved WRKY domain (273-351) and belonged to the WRKY protein family. The phylogenetic tree results showed that HvWRKY1 was most closely related to Hordeum vulgare L. The WRKY family of Qingke, barley, maize and rice were divided into categories I, II, and III, among which HvWRKY1 was located in group III. Results of the quantitative real-time fluorescence PCR (qRT-PCR) showed that the expression of HvWRKY1 was significantly (P < 0.01) higher in leaf stripe infected leaves of Kunlun 14 than that of Z1141. In Arabidopsis thaliana transformed with HvWRKY1, resistance to Botrytis cinerea was enhanced. The RNA-seq analysis showed there were 824 differentially expressed genes (DEGs). Data of the Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment indicated, that a plant-pathogen interaction pathway was enriched. This study is expected to provide a theoretical basis for further studies of functioning of the Qingke gene HvWRKY1 in resistance to the leaf stripe disease. [ABSTRACT FROM AUTHOR]