Sugar Pathways Research Articles

Low light stress promotes new tiller regeneration by changing source-sink relationship and activating expression of expansin genes in wheat.

Low light stress seriously decreased wheat grain number through the formation of aborted spike during the reproductive periodand induced new tiller regeneration to offset the loss of grain number. However, the mechanism by which plants coordinate spike aborted growth and the regeneration of new tillers remains unknown. To better understand this coordinated process, morphological, physiologicaland transcriptomic analyses were performed under low light stress at the young microspore stage. Our findings indicated that leaves exhausted most stored carbohydrates in 1day of darkness. However, spike and uppermost internode (UI) were converted from sink to source, due to increased abscisic acid (ABA) content and decreased cytokinin content. During this process, genes encoding amylases, Sugars Will Eventually be Exported Transporters (SWEET) and sucrose transporters or sucrose carriers (SUT/SUC) were upregulated in spike and UI, which degraded starch into soluble sugars and loaded them into the phloem. Subsequently, soluble sugars were transported to tiller node (TN) where cytokinin and auxin content increased and ABA content decreased, followed by unloading into TN cells by upregulated cell wall invertase (CWINV) genes and highly expressed H+ /hexose symporter genes. Finally, expansin genes integrated the sugar pathway and hormone pathway, and regulate the formation of new tillers directly.

Metabolomics Analysis Reveals Dynamic Accumulation of Sugar and Acid during Stem Development of Brassica juncea

The composition and content of sugar and acid are important indicators of organ development and the quality of horticultural products. B. juncea is an important vegetable in the cruciferous family, with a swollen fleshy stem as the edible organ. Elucidating the characteristics of sugar and acid accumulation during stem expansion of stem mustard and its regulatory mechanism could enhance stem quality. In this study, physiological indicators such as dry matter content, sugar–acid content and related enzyme activities were measured in eight stages of the tumorous stem. The results showed that the sugar and sucrose contents initially increased and then decreased during stem development: Sucrose exhibited a positive correlation with sucrose synthase and sucrose phosphate synthase, while acid content was highly positively correlated with malate dehydrogenase. Further analysis of the dynamic patterns of sugar and acid metabolite contents using metabolomics showed that 1097 metabolites were detected, including 229 organic acids and derivatives, 109 lipids, and other metabolites. Metabolic pathway enrichment analysis showed that metabolites were significantly enriched in organic acids, amino acids, glycolysis/gluconeogenesis, starch, and sucrose metabolism. Analysis of the sugar pathway and the tricarboxylic acid cycle revealed obvious differences in the content and type of metabolites, with most upregulated metabolites in S3 and S4. The expression patterns of enzyme genes associated with the biosynthesis and accumulation of sugar and acid metabolites were found based on differentially expressed genes at different developmental stages, and gene expression levels were verified by qPCR, which showed that the expression patterns of enzyme genes associated with this pathway were highly consistent with the metabolite accumulation. These results suggest that amino acids, sugars, and acids play a critical role in regulating the development of tumorous stems. Results of the present study offer a theoretical basis to improving the quality of mustard by using a metabolomics approach to determine the dynamics of metabolites and related regulatory enzymes during development and the correlation between these levels, which provides novel insights into the potential mechanisms underlying sugar and acid metabolism.

The Sugar Metabolic Model of Aspergillus niger Can Only Be Reliably Transferred to Fungi of Its Phylum.

Fungi play a critical role in the global carbon cycle by degrading plant polysaccharides to small sugars and metabolizing them as carbon and energy sources. We mapped the well-established sugar metabolic network of Aspergillus niger to five taxonomically distant species (Aspergillus nidulans, Penicillium subrubescens, Trichoderma reesei, Phanerochaete chrysosporium and Dichomitus squalens) using an orthology-based approach. The diversity of sugar metabolism correlates well with the taxonomic distance of the fungi. The pathways are highly conserved between the three studied Eurotiomycetes (A. niger, A. nidulans, P. subrubescens). A higher level of diversity was observed between the T. reesei and A. niger, and even more so for the two Basidiomycetes. These results were confirmed by integrative analysis of transcriptome, proteome and metabolome, as well as growth profiles of the fungi growing on the corresponding sugars. In conclusion, the establishment of sugar pathway models in different fungi revealed the diversity of fungal sugar conversion and provided a valuable resource for the community, which would facilitate rational metabolic engineering of these fungi as microbial cell factories.

Potential Metabolic Pathways and Related Processes Involved in Pericarp Browning for Postharvest Pomegranate Fruits

Pericarp browning occurs widely in postharvest pomegranate fruit, but little is known about its mechanism. In this study, ‘Baiyushizi’, a browning-sensitive cultivar, was used to investigate the physiological and genetic changes during pericarp browning. The pericarp browning index (BI) increased greatly after 3 d storage at room temperature, and, consequently, the fruit appearance became unattractive after 6 d. The increasing concentration of malondialdehyde (MDA) and electrolyte leakage were detected in browning pericarp. Polyphenol oxidase (PPO) activity increased significantly after 3 d, while ascorbate peroxidase (APX) and catalase (CAT) activity decreased steadily during storage. Total phenolics content decreased gradually during storage, while ascorbic acid (AsA) and glutathione (GSH) contents increased firstly, then declined. Differentially expressed genes (DEGs) of pericarp under different browning degrees were identified in the metabolic processes of phenolic compounds, lipids, ascorbic acid, glutathione, sugar, starch, energy-related, ethylene biosynthesis and signal transduction pathways. Accordingly, the potential metabolic pathways and related processes involved in pericarp browning were described. The results not only provided insights on the genetic mechanism of pericarp browning in pomegranate but also guidance on controlling postharvest fruit browning in general.

Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging: Diagnostic Pathways and Metabolites for Renal Tumor Entities

Background: Correct tumor subtyping of primary renal tumors is essential for treatment decision in daily routine. Most of the tumors can be classified based on morphology alone. Nevertheless, some diagnoses are difficult, and further investigations are needed for correct tumor subtyping. Besides histochemical investigations, high-mass-resolution matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) can detect new diagnostic biomarkers and hence improve the diagnostic. Patients and Methods: Formalin-fixed paraffin embedded tissue specimens from clear cell renal cell carcinoma (ccRCC, n = 552), papillary renal cell carcinoma (pRCC, n = 122), chromophobe renal cell carcinoma (chRCC, n = 108), and renal oncocytoma (rO, n = 71) were analyzed by high-mass-resolution MALDI fourier-transform ion cyclotron resonance (FT-ICR) MSI. The SPACiAL pipeline was executed for automated co-registration of histological and molecular features. Pathway enrichment and pathway topology analysis were performed to determine significant differences between RCC subtypes. Results: We discriminated the four histological subtypes (ccRCC, pRCC, chRCC, and rO) and established the subtype-specific pathways and metabolic profiles. rO showed an enrichment of pentose phosphate, taurine and hypotaurine, glycerophospholipid, amino sugar and nucleotide sugar, fructose and mannose, glycine, serine, and threonine pathways. ChRCC is defined by enriched pathways including the amino sugar and nucleotide sugar, fructose and mannose, glycerophospholipid, taurine and hypotaurine, glycine, serine, and threonine pathways. Pyrimidine, amino sugar and nucleotide sugar, glycerophospholipids, and glutathione pathways are enriched in ccRCC. Furthermore, we detected enriched phosphatidylinositol and glycerophospholipid pathways in pRCC. Conclusion: In summary, we performed a classification system with a mean accuracy in tumor discrimination of 85.13%. Furthermore, we detected tumor-specific biomarkers for the four most common primary renal tumors by MALDI-MSI. This method is a useful tool in differential diagnosis and biomarker detection.

Comparative Analysis on the Evolution of Flowering Genes in Sugar Pathway in Brassicaceae.

Sugar plays an important role in regulating the flowering of plants. However, studies of genes related to flowering regulation by the sugar pathway of Brassicaceae plants are scarce. In this study, we performed a comprehensive comparative genomics analysis of the flowering genes in the sugar pathway from seven members of the Brassicaceae, including: Arabidopsis thaliana, Arabidopsis lyrata, Astelia pumila, Camelina sativa, Brassica napus, Brassica oleracea, and Brassica rapa. We identified 105 flowering genes in the sugar pathway of these plants, and they were categorized into nine groups. Protein domain analysis demonstrated that the IDD8 showed striking structural variations in different Brassicaceae species. Selection pressure analysis revealed that sugar pathway genes related to flowering were subjected to strong purifying selection. Collinearity analysis showed that the identified flowering genes expanded to varying degrees, but SUS4 was absent from the genomes of Astelia pumila, Camelina sativa, Brassica napus, Brassica oleracea, and Brassica rapa. Tissue-specific expression of ApADG indicated functional differentiation. To sum up, genome-wide identification revealed the expansion, contraction, and diversity of flowering genes in the sugar pathway during Brassicaceae evolution. This study lays a foundation for further study on the evolutionary characteristics and potential biological functions of flowering genes in the sugar pathway of Brassicaceae.

Synthesis and mammalian cell compatibility of light-released glycan precursors for controlled metabolic engineering

Sugar additions to biomolecules, or glycans, are some of the most abundant biomolecule modifications in biology because they enable cells to adapt to changing nutrient and stress conditions. An unmet challenge for the field of glycobiology is the study of glycan biosynthetic pathways with chemical control, especially in live cell settings. The objective of this study was to create biocompatible glycan precursors with controlled release properties. Here, we report eleven “caged” sugar probes that release glycan biosynthetic precursor molecules upon light exposure. The specific sugar pathways we target with our probes regulate the addition of the N-acetyl sugars GlcNAc, GalNAc, and sialic acid onto biomolecules in cells, each of which has the potential to alter glycan processes involved in cell morphology, signaling, and behavior. We hypothesized that our glycan precursor probes would remain biologically inert until light-initiated decaging conditions were met, avoiding biological activities including metabolism and cytotoxicity. The photocaged analogs of GlcNAc, GalNAc, and ManNAc (sialic acid precursor) sugars, which we call “photo-sugars,” were released within minutes of light exposure at their optimal wavelengths. During the course of the study, we characterized the cell compatibility of these sugars under their respective decaging conditions, and found highly cell compatible GlcNAc, GalNAc, and ManNAc photocaged precursors. Release of GlcNAc-1-phosphate precursors led to altered ATP levels in cells, demonstrating preliminary metabolic engineering. We envision these probes as useful additions to the chemical glycobiology field that will enable spatiotemporal control over glycosylation pathways in living mammalian cells.

Transcriptomic and Metabolomic Analysis of Quality Changes during Sweet Cherry Fruit Development and Mining of Related Genes.

Sweet cherries are economically important fruit trees, and their quality changes during development need to be determined. The mechanism of fruit quality changes in sweet cherries were determined by analyzing sweet cherry fruits at 12 developmental stages. The results showed that the soluble sugar, anthocyanin content, and hormones of sweet cherries all changed drastically during the color transition. Therefore, the fruits at the beginning of color conversion, at the end of color conversion, and at the ripening state were selected for the comprehensive analysis of their metabolome and transcriptome. Different sugars, such as D-glucose, sucrose, and trehalose, were identified in the metabolome. Dihydroquercetin, delphinidin-3-glucoside, cyanidin-3-rutincoside, and other flavonoid species were also identified. D-glucose and cyanidin-3-rutinoside were among the most important components of sweet cherry soluble sugars and anthocyanins, respectively. The transcriptional analysis identified key structural genes and nine transcription factors involved in the ABA, sugar, organic acid, and anthocyanin synthesis pathways, with the following specific regulatory patterns. NAC71, WRKY57, and WRKY3 regulate fruit sugar accumulation mainly by acting on INV, SPS, and SUS. MYC2 is involved in the synthesis of anthocyanin precursors by activating PAL and C4H, whereas TCP7 mainly regulates CHI and F3H. WRKY3, NAC71, and WRKY57 have important positive regulatory significance on anthocyanin accumulation, mainly by activating the expression of DFR, ANS, and 3GT.

The Complementary Role of Exercise and Fasting in the Treatment of Cancer: A Narrative Review of Mechanisms Related to Metabolic Stress Elements

Background: Complementary methods such as physical activity (PA) and fasting are particularly important for cancer patients. The present study reviewed the effects of regular PA and fasting on cancer patients and attempted to explain the relevant mechanisms. Methods: Several electronic databases such as PubMed, Elsevier, and Google Scholar were searched for keywords. After reviewing, 412 articles were identified until February 1, 2021. The inclusion criteria included meta-analysis, clinical intervention studies that considered different effects of fasting and various types of exercise on health indicators. After carefully reviewing and eliminating duplicates, 68 articles were identified based on the PICO format (participants, intervention, comparison, and results). Results: The short-term fasting (STF) before chemotherapy (48-72 hours) or rehabilitation exercise could be modulating fasting blood sugar, growth factors, oxidative stress (OS), and inflammatory pathways. In addition, physiological metabolic stress induced by STF or rehabilitation exercise could regulate sex hormone-binding globulin, fat oxidation, leptin secretion, hyperinsulinemia, maintaining mass muscle, and bone density, boosting the immune system, and improving the therapeutic index of cancer. Conclusion: Metabolic stress in cancer cells leads to the intake of high doses of chemotherapy. The rehabilitation exercise prevents the complications of the disease and improves the patient’s quality of life. Thus, these interventions can be used to improve the cancer-based therapeutic index on individual differences.

A199 UTILIZATION OF MUCUS-DERIVED O-GLYCAN SUGARS BY THE PATHOGEN C. RODENTIUM FACILITATE ITS COLONIZATION OF THE MURINE GUT

BackgroundThe ability of enteric pathogens to colonize and expand within the mammalian gastrointestinal (GI) tract is determined by several factors, including the ability to find and acquire nutrients. The thick mucus layer that lines the inner surface of the large intestine is rich in sugars that can serve as nutrient sources for several members of the microbiota. Whether these sugars can also be used by invading bacterial pathogens to colonize the GI tract is still unclear, in particular for the family of attaching and effacing (A/E) bacterial pathogens, including the human diarrheal pathogens EHEC and EPEC.AimsTo investigate the ability of the murine A/E pathogen Citrobacter rodentium to use mucin-derived sugars as a nutrient source, and the importance of these sugars in the virulence of C. rodentium during in-vivo infection.MethodsTo identify which sugar(s) are required for C. rodentium to colonize and grow in the murine GI tract, we generated mutants lacking single or multiple genes involved in the uptake and catabolism of mucin-derived O-glycan sugars. This was followed by in-vitro growth assays in minimal media supplemented with mucin sugars to investigate the growth properties of C. rodentium and the generated mutants on mucin sugars.ResultsWe determined that C. rodentium was able to use three mucin O-glycan sugars: sialic acid, galactose, and N-acetylglucosamine (GlcNAc) as both carbon and nitrogen sources for in-vitro growth. C. rodentium exhibited the maximal growth rate and density on GlcNAc, followed by sialic acid, and finally galactose. A mutant C. rodentium strain carrying a deletion in the nagA gene was unable to grow on both GlcNAc and sialic acid, confirming that the breakdown pathways for these two sugars merge and are processed by shared suite of enzymes. As for galactose, combined deletions in the genes mglB and galP were required to abolish growth on this sugar. Notably, a mutant strain carrying simultaneous deletions in nagA, mglB, and galP was unable to grow on all three mucin sugars, as well as on purified mucin.ConclusionsOur results demonstrate that intestinal mucin sugars serve as potential nutrient sources for C. rodentium and that C. rodentium can catabolize three of these sugars. Future work will examine whether these sugar pathways contribute to C. rodentium colonization of the murine GI tract.Funding AgenciesCCC, CIHRCH.I.L.D. Fdn

Genetic variation in YIGE1 contributes to ear length and grain yield in maize.

Ear length (EL), which is controlled by quantitative trait loci (QTLs), is an important component of grain yield and as such is a key target trait in maize breeding. However, very few EL QTLs have been cloned, and their molecular mechanisms are largely unknown. Here, using a genome wide association study (GWAS), we identified a QTL, YIGE1, which encodes an unknown protein that regulates EL by affecting pistillate floret number. Overexpression of YIGE1 increased female inflorescence meristem (IM) size, increased EL and kernel number per row (KNPR), and thus enhanced grain yield. By contrast, CRISPR/Cas9 knockout and Mutator insertion mutant lines of YIGE1 displayed decreased IM size and EL. A single-nucleotide polymorphism (SNP) located in the regulatory region of YIGE1 had a large effect on its promoter strength, which positively affected EL by increasing gene expression. Further analysis shows that YIGE1 may be involved in sugar and auxin signal pathways to regulate maize ear development, thus affecting IM activity and floret production in maize inflorescence morphogenesis. These findings provide new insights into ear development and will ultimately facilitate maize molecular breeding.

Seaweeds as a sustainable source of bioenergy: Techno-economic and life cycle analyses of its biochemical conversion pathways

This study evaluates the environmental impacts, economic potential, and merits of producing bioenergy from seaweed via biological conversion pathways, including the: 1) sugar pathway; (2) volatile fatty acids pathway; and (3) methane pathway to produce ethanol, ethanol and heavier alcohols, and heat and power, respectively. The maximum seaweed price and minimum product selling price are both calculated as economic indicators. Overall, results demonstrate that the sugar platform is economically superior, as it provides a higher average maximum seaweed price of USD 121.6/t compared with USD 57.7/t and USD 24.2/t for volatile fatty acids platform and methane platform, respectively. The minimum product selling price calculated for a range of biomass purchase prices (USD 50–150/dry t) and plant scales (100,000–700,000 dry t of seaweed) indicated that the sugar platform is capable of selling ethanol at prices lower than its 2019 wholesale price (USD 1.38/gal) at smaller plant scales and higher seaweed price compared with volatile fatty acids platform. Cradle-to-grave life cycle assessments were conducted to identify the key drivers of its environmental profile. Three scenarios for the preparation and transportation of seaweed were considered, namely: (1) grinding + pumping; (2) chopping + wet transportation; and (3) chopping + dry transportation. Seaweed grinding and pumping in the biorefinery was identified to be the most sustainable mode of transportation. In addition, our results demonstrated that biofuels can lead to better environmental profiles compared with generation of bioelectricity, as a larger burden is displaced by substituting fossil fuels in the transportation sector.

Integrated Transcriptomics and Metabolomics Analysis Reveal Key Metabolism Pathways Contributing to Cold Tolerance in Peanut.

Low temperature (non-freezing) is one of the major limiting factors in peanut (Arachis hypogaea L.) growth, yield, and geographic distribution. Due to the complexity of cold-resistance trait in peanut, the molecular mechanism of cold tolerance and related gene networks were largely unknown. In this study, metabolomic analysis of two peanut cultivars subjected to chilling stress obtained a set of cold-responsive metabolites, including several carbohydrates and polyamines. These substances showed a higher accumulation pattern in cold-tolerant variety SLH than cold-susceptible variety ZH12 under cold stress, indicating their importance in protecting peanut from chilling injuries. In addition, 3,620 cold tolerance genes (CTGs) were identified by transcriptome sequencing, and the CTGs were most significantly enriched in the “phenylpropanoid biosynthesis” pathway. Two vital modules and several novel hub genes were obtained by weighted gene co-expression network analysis (WGCNA). Several key genes involved in soluble sugar, polyamine, and G-lignin biosynthetic pathways were substantially higher and/or responded more quickly in SLH (cold tolerant) than ZH12 (cold susceptible) under low temperature, suggesting they might be crucial contributors during the adaptation of peanut to low temperature. These findings will not only provide valuable resources for study of cold resistance in peanut but also lay a foundation for genetic modification of cold regulators to enhance stress tolerance in crops.

Effect of exogenous N-acyl-homoserine lactones on the anammox process at 15 ℃: Nitrogen removal performance, gene expression and metagenomics analysis

In this study, C6-HSL and C8-HSL were separately introduced into anammox biofilm reactors to facilitate the anammox performance at 15 ℃. After operation 138 d, total nitrogen removal efficiencies in reactors with amendment C6-HSL or C8-HSL at 15 ℃ reached 76.2% and 74.6%, respectively. Content of extracellular polymeric substances increased by 19.8%, 67.7% and 121.2% in control group, C6-HSL and C8-HSL addition group, respectively. Genes associated with nitrogen removal (i.e., hzo, hzsB, nirS, and ccsB) showed higher expression level at amendment C6-HSL or C8-HSL group. Metagenomics analysis found that amendment of C6-HSL or C8-HL resulted in an increased abundance of genes related to the tricarboxylic acid cycle, amino sugar and nucleotide sugar metabolism, and also genes associated with amino acid biosynthesis pathways. Overall, amendment C6-HSL or C8-HSL had been confirmed as the effective method to improve the performance of anammox bioreactor at 15 ℃.

Biosynthesis of UDP-2-acetamido-4-formamido-2,4,6-trideoxy-hexose by WekG, WekE, WekF, and WekD: Enzymes in the Wek pathway responsible for O-antigen Assembly in Escherichia coli O119

Considering the importance of bacterial glycoconjugates on virulence and host mimicry, there is a need to better understand the biosynthetic pathways of these unusual sugars to identify critical targets involved in bacterial pathogenesis. In this report, we describe the cloning, overexpression, purification, and biochemical characterization of the four central enzymes in the biosynthesis pathway for UDP-2-acetamido-4-formamido-2,4,6-trideoxy-hexose, WekG, WekE, WekF, and WekD. Product peaks from enzyme-substrate reactions were detected by using a combination of capillary electrophoresis (CE) and electrospray ionization-mass spectrometry (ESI-MS). Putative enzyme assignments were provided by protein sequence analysis. Combined with the mass spectrometric characterization of pathway intermediates, we propose a biosynthetic pathway for UDP-2-acetamido-4-formamido-2,4,6-trideoxy-hexose. This process involves C-4, C-6 dehydration, C-4 amination, and formylation. CID-ESI-MSn result confirmed that the final product is a 4 formamido derivative too rather than the 3 formamido derivatives as reported earlier.

Selective Inhibition of Heparan Sulphate and Not Chondroitin Sulphate Biosynthesis by a Small, Soluble Competitive Inhibitor.

The glycosaminoglycan, heparan sulphate (HS), orchestrates many developmental processes. Yet its biological role has not yet fully been elucidated. Small molecule chemical inhibitors can be used to perturb HS function and these compounds provide cheap alternatives to genetic manipulation methods. However, existing chemical inhibition methods for HS also interfere with chondroitin sulphate (CS), complicating data interpretation of HS function. Herein, a simple method for the selective inhibition of HS biosynthesis is described. Using endogenous metabolic sugar pathways, Ac4GalNAz produces UDP-GlcNAz, which can target HS synthesis. Cell treatment with Ac4GalNAz resulted in defective chain elongation of the polymer and decreased HS expression. Conversely, no adverse effect on CS production was observed. The inhibition was transient and dose-dependent, affording rescue of HS expression after removal of the unnatural azido sugar. The utility of inhibition is demonstrated in cell culture and in whole organisms, demonstrating that this small molecule can be used as a tool for HS inhibition in biological systems.

The dissection of R genes and locus Pc5.1 in Phytophthora capsici infection provides a novel view of disease resistance in peppers

BackgroundPhytophthora capsici root rot (PRR) is a disastrous disease in peppers (Capsicum spp.) caused by soilborne oomycete with typical symptoms of necrosis and constriction at the basal stem and consequent plant wilting. Most studies on the QTL mapping of P. capsici resistance suggested a consensus broad-spectrum QTL on chromosome 5 named Pc.5.1 regardless of P. capsici isolates and resistant resources. In addition, all these reports proposed NBS-ARC domain genes as candidate genes controlling resistance.ResultsWe screened out 10 PRR-resistant resources from 160 Capsicum germplasm and inspected the response of locus Pc.5.1 and NBS-ARC genes during P. capsici infection by comparing the root transcriptomes of resistant pepper 305R and susceptible pepper 372S. To dissect the structure of Pc.5.1, we anchored genetic markers onto pepper genomic sequence and made an extended Pc5.1 (Ext-Pc5.1) located at 8.35 Mb–38.13 Mb on chromosome 5 which covered all Pc5.1 reported in publications. A total of 571 NBS-ARC genes were mined from the genome of pepper CM334 and 34 genes were significantly affected by P. capsici infection in either 305R or 372S. Only 5 inducible NBS-ARC genes had LRR domains and none of them was positioned at Ext-Pc5.1. Ext-Pc5.1 did show strong response to P. capsici infection and there were a total of 44 differentially expressed genes (DEGs), but no candidate genes proposed by previous publications was included. Snakin-1 (SN1), a well-known antimicrobial peptide gene located at Pc5.1, was significantly decreased in 372S but not in 305R. Moreover, there was an impressive upregulation of sugar pathway genes in 305R, which was confirmed by metabolite analysis of roots. The biological processes of histone methylation, histone phosphorylation, DNA methylation, and nucleosome assembly were strongly activated in 305R but not in 372S, indicating an epigenetic-related defense mechanism.ConclusionsThose NBS-ARC genes that were suggested to contribute to Pc5.1 in previous publications did not show any significant response in P. capsici infection and there were no significant differences of these genes in transcription levels between 305R and 372S. Other pathogen defense-related genes like SN1 might account for Pc5.1. Our study also proposed the important role of sugar and epigenetic regulation in the defense against P. capsici.

External application of nitrogen alleviates toxicity of cadmium on poplars via starch and sucrose metabolism.

Phytoremediation technology can help achieve moderate cost and considerable effect with respect to the remediation of heavy metal (HM) pollution in soil and water. Many previous studies have suggested the role of nitrogen (N) in the alleviation of effects of HM on plants. Herein, we sought to determine the molecular mechanisms by which additional N supplementation mitigates cadmium (Cd) toxicity in poplars using a combination of physiological, transcriptomic and phosphoproteomic analyses. The application of N can alleviate the toxicity of Cd to Populus by reducing chlorophyll degradation, maintaining the stability of ions inside and outside the cell membrane and increasing the soluble sugar content. Plant samples from the control, Cd stress and Cd_N treatments were used for an integrated analysis of the transcriptome, as well as for phosphoproteomics analysis. Moreover, 1314 differentially expressed genes and 119 differentially expressed kinase genes were discovered. Application of additional N under Cd stress promoted the phosphorylation process. Furthermore, 51 significantly enriched phosphorylated protein sites and 23 differentially expressed kinases were identified using phosphoproteomic and proteomic analyses. Importantly, transcriptomic and phosphoproteomic analyses jointly determined that the application of N could activate corresponding gene expression [UDP-glucose-dehydrogenase (UGD), GAUT, PME, pectin lyase, UDP-glucose-pyrophosphorylase 2 (UGP2), sucrose phosphate synthase (SPS), SUS and SPP2] and protein phosphorylation (UGP2 and SPS) in the sugar and starch synthesis pathways, which promoted the synthesis of sucrose and soluble sugar and subsequently alleviated the damage caused by Cd.

A Complex Gene Network Mediated by Ethylene Signal Transduction TFs Defines the Flower Induction and Differentiation in Olea europaea L.

The olive tree (Olea europaea L.) is a typical Mediterranean crop, important for olive and oil production. The high tendency to bear fruits in an uneven manner, defined as irregular or alternate bearing, results in a significant economic impact for the high losses in olives and oil production. Buds from heavy loaded (‘ON’) and unloaded (‘OFF’) branches of a unique olive tree were collected in July and the next March to compare the transcriptomic profiles and get deep insight into the molecular mechanisms regulating floral induction and differentiation. A wide set of DEGs related to ethylene TFs and to hormonal, sugar, and phenylpropanoid pathways was identified in buds collected from ‘OFF’ branches. These genes could directly and indirectly modulate different pathways, suggesting their key role during the lateral bud transition to flowering stage. Interestingly, several genes related to the flowering process appeared as over-expressed in buds from March ‘OFF’ branches and they could address the buds towards flower differentiation. By this approach, interesting candidate genes related to the switch from vegetative to reproductive stages were detected and analyzed. The functional analysis of these genes will provide tools for developing breeding programs to obtain olive trees characterized by more constant productivity over the years.

The Rice Small Auxin-Up RNA Gene OsSAUR33 Regulates Seed Vigor via Sugar Pathway during Early Seed Germination.

Seed vigor affects seed germination and seedling emergence, and therefore is an important agronomic trait in rice. Small auxin-up RNAs (SAURs) function in a range of developmental processes, but their role in seed vigor remains unclear. Here, we observed that disruption of OsSAUR33 resulted in reduced germination rates and low seed uniformity in early germination. Expression of OsSAUR33 was higher in mature grains and early germinating seeds. RNA-seq analysis revealed that OsSAUR33 modulated seed vigor by affecting the mobilization of stored reserves during germination. Disruption of OsSAUR33 increased the soluble sugar content in dry mature grains and seeds during early germination. OsSAUR33 interacted with the sucrose non-fermenting-1-related protein kinase OsSnRK1A, a regulator of the sugar signaling pathway, which influences the expression of sugar signaling-related genes during germination. Disruption of OsSAUR33 increased sugar-sensitive phenotypes in early germination, suggesting OsSAUR33 likely affects seed vigor through the sugar pathway. One elite haplotype of OsSAUR33 associated with higher seed vigor was identified mainly in indica accessions. This study provides insight into the effects of OsSAUR33 on seed vigor in rice.