Regulation of hormone pathways in wheat infested by Blumeria graminis f. sp. tritici.

BACKGROUND: Wheat powdery mildew is an obligate biotrophic pathogen infecting wheat, which can pose a serious threat to wheat production. In this study, transcriptome sequencing was carried out on wheat leaves infected by Blumeria graminis f. sp. tritici from 0 h to 7 d. RESULTS: KEGG and GO enrichment analysis revealed that the upstream biosynthetic pathways and downstream signal transduction pathways of salicylic acid, jasmonic acid, and ethylene were highly enriched at all infection periods. Trend analysis showed that the expressions of hormone-related genes were significantly expressed from 1 to 4 d, suggesting that 1 d-4 d is the main period in which hormones play a defensive role. During this period of time, the salicylic acid pathway was up-regulated, while the jasmonic acid and ethylene pathways were suppressed. Meanwhile, four key modules and 11 hub genes were identified, most of which were hormone related. CONCLUSION: This study improves the understanding of the dynamical responses of wheat to Blumeria graminis f. sp. tritici infestation at the transcriptional level and provides a reference for screening core genes regulated by hormones.

Identification of Key Modules and Candidate Genes for Powdery Mildew Resistance of Wheat-Agropyron cristatum Translocation Line WAT-2020-17-6 by WGCNA

As one of the serious diseases of wheat, powdery mildew (Blumeria graminis f. sp. tritici) is a long-term threat to wheat production. Therefore, it is of great significance to explore new powdery mildew-resistant genes for breeding. The wild relative species of wheat provide gene resources for resistance to powdery mildew breeding. Agropyron cristatum (2n = 4x = 28, genomes PPPP) is an important wild relative of wheat, carrying excellent genes for high yield, disease resistance, and stress resistance, which can be used for wheat improvement. To understand the molecular mechanism of powdery mildew resistance in the wheat-A. cristatum translocation line WAT2020-17-6, transcriptome sequencing was performed, and the resistance genes were analyzed by weighted gene co-expression network analysis (WGCNA). In the results, 42,845 differentially expressed genes were identified and divided into 18 modules, of which six modules were highly correlated with powdery mildew resistance. Gene ontology (GO) enrichment analysis showed that the six interested modules related to powdery mildew resistance were significantly enriched in N-methyltransferase activity, autophagy, mRNA splicing via spliceosome, chloroplast envelope, and AMP binding. The candidate hub genes of the interested modules were further identified, and their regulatory relationships were analyzed based on co-expression data. The temporal expression pattern of the 12 hub genes was verified within 96 h after powdery mildew inoculation by RT-PCR assay. In this study, we preliminarily explained the resistance mechanism of the wheat-A. cristatum translocation lines and obtained the hub candidate genes, which laid a foundation in the exploration of resistance genes in A. cristatum for powdery mildew-resistant breeding in wheat.

Development and identification of an elite wheat-Hordeum californicum T6HcS/6BL translocation line ND646 containing several desirable traits.

Hordeum californicum (H. californicum, 2n=2X=14, HcHc), one of the wild relatives of wheat (Triticum aestivum L.), harbors many desirable genes and is a potential genetic resource for wheat improvement. In this study, an elite line ND646 was selected from a BC4F5 population, which was developed using 60Co-γ irradiated wheat-H. californicum disomic addition line WJ28-1 (DA6Hc) as the donor parent and Ningchun 4 as the recurrent parent. ND646 was identified as a novel wheat-H. californicum 6HcS/6BL translocation line using genomic in situ hybridization (GISH), fluorescence in situ hybridization (FISH), and H. californicum-specific expressed sequence tag (EST) markers. Further evaluation revealed that ND646 had excellent performance in several traits, such as a higher sedimentation value (SV), higher water absorption rate (WAR), and higher hardness index (HI). More importantly, it had more kernels per spike (KPS), a higher grain yields (GY), and good resistance to powdery mildew, leaf rust, and 2,4-D butylate (2,4-D). Its excellent phenotypic performance laid the foundation for further investigation of its genetic architecture and makes ND646 a useful germplasm resource for wheat breeding.

Genome-wide identification of the jumonji C domain- containing histone demethylase gene family in wheat and their expression analysis under drought stress.

Methylation and demethylation of histone play a crucial role in regulating chromatin formation and gene expression. The jumonji C (JmjC) domain-containing proteins are demethylases that are involved in regulating epigenetic modification in plants. In our study, the JmjC genes in Triticum aestivum L., Triticum turgidum L., Triticum dicoccoides L., Triticum urartu L., and Aegilops tauschii L. were identified. Phylogenetic relationship and colinearity analysis revealed that the wheat JmjC genes were conserved in A, B, and D subgenomes during evolution. Cis-acting elements analysis showed that elements related to stress response, hormone response, and light response were found in wheat JmjC genes. The expression of JmjC genes was affected by tissue types and developmental stages, and members of the same subfamily tended to have similar expression patterns in wheat. They also showed a unique expression pattern in root during PEG (Polyethylene glycol) treatment. In conclusion, comprehensive analysis indicated that three members (Tr-1A-JMJ2, Tr-1B-JMJ2, and Tr-1D-JMJ2) might be regulated by several hormones and function in the early stages of drought stress, while eight members (Tr-1B-JMJ3, Tr-4B-JMJ1, Tr-7A-JMJ1, etc.) displayed a significantly high expression after 24 h of PEG treatment, indicating a role in the later stages of drought stress. This research presents the first genome-wide study of the JmjC family in wheat, and lays the foundation for promoting the study of their functional characterization in wheat drought resistance.

TMT based proteomic profiling of Sophora alopecuroides leaves reveal flavonoid biosynthesis processes in response to salt stress.

Salt stress is the major abiotic stress worldwide, adversely affecting crop yield and quality. Utilizing salt tolerance genes for the genetic breeding of crops is one of the most effective measures to withstand salinization. Sophora alopecuroides is a well-known saline-alkaline and drought-tolerant medicinal plant. Understanding the underlying molecular mechanism for Sophora alopecuroides salt tolerance is crucial to identifying the salt-tolerant genes. In this study, we performed tandem mass tag (TMT) based proteomic profiling of S. alopecuroides leaves under 150 mM NaCl induced salt stress condition for 3 d and 7 d. Data are available on ProteomeXchange (PXD027627). Furthermore, the proteomic findings were validated through parallel reaction monitoring (PRM). We observed that the expression levels of several transporter proteins related to the secondary messenger signaling pathway were altered under salt stress conditions induced for 3 d. However, the expression of the certain transferase, oxidoreductase, dehydrogenase, which are involved in the biosynthesis of flavonoids, alkaloids, phenylpropanoids, and amino acid metabolism, were mainly alerted after 7 d post-salt-stress induction. Several potential genes that might be involved in salt stress conditions were identified; however, it demands further investigation. Although salt stress affects the level of secondary metabolites, their correlation needs to be investigated further. SIGNIFICANCE: Salinization is the most severe abiotic adversity, which has had a significant negative effect on world food security over the time. Excavating salt-tolerant genes from halophytes or medicinal plants is one of the important measures to cope with salt stress. S. alopecuroides is a well-known medicinal plant with anti-tumor, anti-inflammatory, and antibacterial effects, anti-saline properties, and resistance to drought stress. Currently, only a few studies have explored the S. alopecuroides' gene function, and regulation and these studies are mostly related to the unpublished genome sequence information of S. alopecuroides. Recently, transcriptomics and metabolomics studies have been carried on the abiotic stress in S. alopecuroides roots. Multiple studies have shown that altered gene expression at the transcript level and altered metabolite levels do not correspond to the altered protein levels. In this study, TMT and PRM based proteomic analyses of S. alopecuroides leaves under salt stress condition induced using 150 mM NaCl for 3 d and 7 d was performed. These analyses elucidated the activation of different mechanisms in response to salt stress. A total of 434 differentially abundant proteins (DAPs) in salt stress conditions were identified and analyzed. For the first time, this study utilized proteomics technology to dig out plentiful underlying salt-tolerant genes from the medicinal plant, S. alopecuroides. We believe that this study will be of great significance to crop genetics and breeding.

Cytochalasan and Tyrosine-Derived Alkaloids from the Marine Sediment-Derived Fungus Westerdykella dispersa and Their Bioactivities.

Six new cytochalasans, designated as 18-oxo-19,20-dihydrophomacin C (1), 18-oxo-19-methoxy-19,20- dihydrophomacin C (2), 18-oxo-19-hydroxyl-19,20-dihydrophomacin C (3), 19,20-dihydrophomacin C (4), 19-methoxy-19,20-dihydrophomacin C (5), 19-hydroxyl-19,20-dihydrophomacin C (6), and one new tyrosine-derived alkaloid named as gymnastatin Z (8), together with two known compounds, phomacin B (7) and triticone D (9), were isolated from a solid-substrate fermentation culture of Westerdykella dispersa which was derived from marine sediments. Their structures were established on the basis of spectroscopic analysis using 1D and 2D NMR techniques, and comparison of NMR data to those of known compounds. The anti-bacterial and cytotoxic activities assays of all isolated compounds were evaluated against eight human pathogenic bacteria and five human cancer cell lines, respectively. Compound 8 exhibited moderate activity against B. subtilis with MIC values of 12.5 µg/mL, while compounds 5, 7 and 8 displayed moderate inhibitory activities against five human cancer cell lines (MCF-7, HepG2, A549, HT-29 and SGC-7901), with IC50 values ranging from 25.6 to 83.7 µM.

Indole Derivatives Produced by the Metagenome Genes of the Escherichia coli-Harboring Marine Sponge Discodermia calyx.

Three indole derivatives, a novel benzoxazine-indole hybrid (1) and two known indole trimers (2, 3), were isolated from the metagenomic library of the marine sponge Discodermia calyx based on functional screening. Their structures were elucidated by extensive spectroscopic analysis and comparison of their NMR data to that of known compounds. The antibacterial assay indicated that only compound 2 displayed significant antibacterial activity against Bacillus cereus, with approximately 20 mm diameter growth inhibition at 10 µg/paper. HPLC analyses revealed that compound 2 is a newly induced metabolite, and the concentration of 3 was obviously enhanced in contrast to negative control, while 1 was not detected, allowing us to predict that the formation of 2 might be induced by exogenous genes derived from the sponge metagenome, whereas compound 1 could be formed through a non-enzymatic process during the isolation procedure.