Metabolic Enabling and Detoxification by Mammalian Gut Microbes.

The longstanding interactions between mammals and their symbionts enable thousands of mammal species to consume herbivorous diets. The microbial communities in mammals degrade both plant fiber and toxins. Microbial toxin degradation has been repeatedly documented in domestic ruminants, but similar work in wild mammals is more limited due to constraints on sampling and manipulating the microbial communities in these species. In this review, we briefly describe the toxins commonly encountered in mammalian diets, major classes of biotransformation enzymes in microbes and mammals, and the gut chambers that house symbiotic microbes. We next examine evidence for microbial detoxification in domestic ruminants before providing case studies on microbial toxin degradation in both foregut- and hindgut-fermenting wild mammals. We end by discussing species that may be promising for future investigations, and the advantages and limitations of approaches currently available for studying degradation of toxins by mammalian gut microbes.

Root-exuded specialized metabolites reduce arsenic toxicity in maize.

By releasing specialized metabolites, plants modify their environment. Whether and how specialized metabolites protect plants against toxic levels of trace elements is not well understood. We evaluated whether benzoxazinoids, which are released into the soil by major cereals, can confer protection against arsenic toxicity. Benzoxazinoid-producing maize plants performed better in arsenic-contaminated soils than benzoxazinoid-deficient mutants in the greenhouse and the field. Adding benzoxazinoids to the soil restored the protective effect, and the effect persisted to the next crop generation via positive plant-soil feedback. Arsenate levels in the soil and total arsenic levels in the roots were lower in the presence of benzoxazinoids. Thus, the protective effect of benzoxazinoids is likely soil-mediated and includes changes in soil arsenic speciation and root accumulation. We conclude that exuded specialized metabolites can enhance protection against toxic trace elements via soil-mediated processes and may thereby stabilize crop productivity in polluted agroecosystems.

Cofunctioning of bacterial exometabolites drives root microbiota establishment.

Soil-dwelling microbes are the principal inoculum for the root microbiota, but our understanding of microbe-microbe interactions in microbiota establishment remains fragmentary. We tested 39,204 binary interbacterial interactions for inhibitory activities in vitro, allowing us to identify taxonomic signatures in bacterial inhibition profiles. Using genetic and metabolomic approaches, we identified the antimicrobial 2,4-diacetylphloroglucinol (DAPG) and the iron chelator pyoverdine as exometabolites whose combined functions explain most of the inhibitory activity of the strongly antagonistic Pseudomonas brassicacearum R401. Microbiota reconstitution with a core of Arabidopsis thaliana root commensals in the presence of wild-type or mutant strains revealed a root niche-specific cofunction of these exometabolites as root competence determinants and drivers of predictable changes in the root-associated community. In natural environments, both the corresponding biosynthetic operons are enriched in roots, a pattern likely linked to their role as iron sinks, indicating that these cofunctioning exometabolites are adaptive traits contributing to pseudomonad pervasiveness throughout the root microbiota.

Complexity of fungal polyketide biosynthesis and function.

Where does one draw the line between primary and secondary metabolism? The answer depends on the perspective. Microbial secondary metabolites (SMs) were at first believed not to be very important for the producers because they are dispensable for growth under laboratory conditions. However, such compounds become important in natural niches of the organisms, and some are of prime importance for humanity. Polyketides are an important group of SMs with aflatoxin as a well-known and well-characterized example. In Aspergillus spp., all 34 afl genes encoding the enzymes for aflatoxin biosynthesis are located in close vicinity on chromosome III in a so-called gene cluster. This led to the assumption that most genes required for polyketide biosynthesis are organized in gene clusters. Recent research, however, revealed an enormous complexity of the biosynthesis of different polyketides, ranging from individual polyketide synthases to a gene cluster producing several compounds, or to several clusters with additional genes scattered in the genome for the production of one compound. Research of the last decade furthermore revealed a huge potential for SM biosynthesis hidden in fungal genomes, and methods were developed to wake up such sleeping genes. The analysis of organismic interactions starts to reveal some of the ecological functions of polyketides for the producing fungi.

Chemical Mediators at the Bacterial-Fungal Interface.

Interactions among microbes are key drivers of evolutionary progress and constantly shape ecological niches. Microorganisms rely on chemical communication to interact with each other and surrounding organisms. They synthesize natural products as signaling molecules, antibiotics, or modulators of cellular processes that may be applied in agriculture and medicine. Whereas major insight has been gained into the principles of intraspecies interaction, much less is known about the molecular basis of interspecies interplay. In this review, we summarize recent progress in the understanding of chemically mediated bacterial-fungal interrelations. We discuss pairwise interactions among defined species and systems involving additional organisms as well as complex interactions among microbial communities encountered in the soil or defined as microbiota of higher organisms. Finally, we give examples of how the growing understanding of microbial interactions has contributed to drug discovery and hypothesize what may be future directions in studying and engineering microbiota for agricultural or medicinal purposes.

Exploring the in vivo anti-cancer potential of Neosetophomone B in leukemic cells using a zebrafish xenograft model.

Neosetophomone B (NSP-B) is a unique meroterpenoid fungal secondary metabolite that has previously demonstrated promising anti-cancer properties against various cancer cell lines in vitro. However, its in vivo anti-cancer potential remaines unexplored. To fill this gap in our knowledge, we tested NSP-B's in vivo anti-cancer activity using a zebrafish model, an organism that has gained significant traction in biomedical research due to its genetic similarities with humans and its transparent nature, allowing real-time tumor growth observation. For our experiments, we employed the K562-injected zebrafish xenograft model. Upon treating these zebrafish with NSP-B, we observed a marked reduction in the size and number of tumor xenografts. Delving deeper, our analyses indicated that NSP-B curtailed tumor growth and proliferation of leukemic grafted xenograft within the zebrafish. These results show that NSP-B possesses potent in vivo anti-cancer properties, making it a potential novel therapeutic agent for addressing hematological malignancies.

Origin and early evolution of the plant terpene synthase family.

As a midsized gene family conserved more by lineage than function, the typical plant terpene synthases (TPSs) could be a valuable tool to examine plant evolution. TPSs are pivotal in biosynthesis of gibberellins and related phytohormones as well as in formation of the extensive arsenal of specialized plant metabolites mediating ecological interactions whose production is often lineage specific. Yet the origin and early evolution of the TPS family is not well understood. Systematic analysis of an array of transcriptomes and sequenced genomes indicated that the TPS family originated after the divergence of land plants from charophytic algae. Phylogenetic and biochemical analyses support the hypothesis that the ancestral TPS gene encoded a bifunctional class I and II diterpene synthase producing the ent-kaurene required for phytohormone production in all extant lineages of land plants. Moreover, the ancestral TPS gene likely underwent duplication at least twice early in land plant evolution. Together these two gave rise to three TPS lineages leading to the extant TPS-c, TPS-e/f, and the remaining TPS (h/d/a/b/g) subfamilies, with the latter dedicated to secondary rather than primary metabolism while the former two contain those genes involved in ent-kaurene production. Nevertheless, parallel evolution from the ent-kaurene­producing class I and class II diterpene synthases has led to roles for TPS-e/f and -c subfamily members in secondary metabolism as well. These results clarify TPS evolutionary history and provide context for the role of these genes in producing the vast diversity of terpenoid natural products observed today in various land plant lineages.

Streptomyces extracellular vesicles are a broad and permissive antimicrobial packaging and delivery system.

Streptomyces are the primary source of bioactive specialized metabolites used in research and medicine, including many antimicrobials. These are presumed to be secreted and function as freely soluble compounds. However, increasing evidence suggests that extracellular vesicles are an alternative secretion system. We assessed environmental and lab-adapted Streptomyces (sporulating filamentous actinomycetes) and found frequent production of antimicrobial vesicles. The molecular cargo included actinomycins, anthracyclines, candicidin, and actinorhodin, reflecting both diverse chemical properties and diverse antibacterial and antifungal activity. The levels of packaged antimicrobials correlated with the level of inhibitory activity of the vesicles, and a strain knocked out for the production of anthracyclines produced vesicles that lacked antimicrobial activity. We demonstrated that antimicrobial containing vesicles achieve direct delivery of the cargo to other microbes. Notably, this delivery via membrane fusion occurred to a broad range of microbes, including pathogenic bacteria and yeast. Vesicle encapsulation offers a broad and permissive packaging and delivery system for antimicrobial specialized metabolites, with important implications for ecology and translation.IMPORTANCEExtracellular vesicle encapsulation changes our picture of how antimicrobial metabolites function in the environment and provides an alternative translational approach for the delivery of antimicrobials. We find many Streptomyces strains are capable of releasing antimicrobial vesicles, and at least four distinct classes of compounds can be packaged, suggesting this is widespread in nature. This is a striking departure from the primary paradigm of the secretion and action of specialized metabolites as soluble compounds. Importantly, the vesicles deliver antimicrobial metabolites directly to other microbes via membrane fusion, including pathogenic bacteria and yeast. This suggests future applications in which lipid-encapsulated natural product antibiotics and antifungals could be used to solve some of the most pressing problems in drug resistance.

Shifts in carbon partitioning by photosynthetic activity increase terpenoid synthesis in glandular trichomes.

Several commercially important secondary metabolites are produced and accumulated in high amounts by glandular trichomes, giving the prospect of using them as metabolic cell factories. Due to extremely high metabolic fluxes through glandular trichomes, previous research focused on how such flows are achieved. The question regarding their bioenergetics became even more interesting with the discovery of photosynthetic activity in some glandular trichomes. Despite recent advances, how primary metabolism contributes to the high metabolic fluxes in glandular trichomes is still not fully elucidated. Using computational methods and available multi-omics data, we first developed a quantitative framework to investigate the possible role of photosynthetic energy supply in terpenoid production and next tested experimentally the simulation-driven hypothesis. With this work, we provide the first reconstruction of specialised metabolism in Type-VI photosynthetic glandular trichomes of Solanum lycopersicum. Our model predicted that increasing light intensities results in a shift of carbon partitioning from catabolic to anabolic reactions driven by the energy availability of the cell. Moreover, we show the benefit of shifting between isoprenoid pathways under different light regimes, leading to a production of different classes of terpenes. Our computational predictions were confirmed in vivo, demonstrating a significant increase in production of monoterpenoids while the sesquiterpenes remained unchanged under higher light intensities. The outcomes of this research provide quantitative measures to assess the beneficial role of chloroplast in glandular trichomes for enhanced production of secondary metabolites and can guide the design of new experiments that aim at modulating terpenoid production.

Genomic insights into Penicillium chrysogenum adaptation to subseafloor sedimentary environments.

BACKGROUND: Penicillium chrysogenum is a filamentous fungal species with diverse habitats, yet little is known about its genetics in adapting to extreme subseafloor sedimental environments. RESULTS: Here, we report the discovery of P. chrysogenum strain 28R-6-F01, isolated from deep coal-bearing sediments 2306 m beneath the seafloor. This strain possesses exceptional characteristics, including the ability to thrive in extreme conditions such as high temperature (45 °C), high pressure (35 Mpa), and anaerobic environments, and exhibits broad-spectrum antimicrobial activity, producing the antibiotic penicillin at a concentration of 358 µg/mL. Genome sequencing and assembly revealed a genome size of 33.19 Mb with a GC content of 48.84%, containing 6959 coding genes. Comparative analysis with eight terrestrial strains identified 88 unique genes primarily associated with penicillin and aflatoxins biosynthesis, carbohydrate degradation, viral resistance, and three secondary metabolism gene clusters. Furthermore, significant expansions in gene families related to DNA repair were observed, likely linked to the strain's adaptation to its environmental niche. CONCLUSIONS: Our findings provide insights into the genomic and biological characteristics of P. chrysogenum adaptation to extreme anaerobic subseafloor sedimentary environments, such as high temperature and pressure.

The evolution of chemodiversity in plants-From verbal to quantitative models.

Plants harbour a great chemodiversity, that is diversity of specialised metabolites (SMs), at different scales. For instance, individuals can produce a large number of SMs, and populations can differ in their metabolite composition. Given the ecological and economic importance of plant chemodiversity, it is important to understand how it arises and is maintained over evolutionary time. For other dimensions of biodiversity, that is species diversity and genetic diversity, quantitative models play an important role in addressing such questions. Here, we provide a synthesis of existing hypotheses and quantitative models, that is mathematical models and computer simulations, for the evolution of plant chemodiversity. We describe each model's ingredients, that is the biological processes that shape chemodiversity, the scales it considers and whether it has been formalized as a quantitative model. Although we identify several quantitative models, not all are dynamic and many influential models have remained verbal. To fill these gaps, we outline our vision for the future of chemodiversity modelling. We identify quantitative models used for genetic variation that may be adapted for chemodiversity, and we present a flexible framework for the creation of individual-based models that address different scales of chemodiversity and combine different ingredients that bring this chemodiversity about.

Does spatial variation in insect herbivory match variations in plant quality? A meta-analysis.

Variation in herbivore pressure has often been predicted from patterns in plant traits considered as antiherbivore defences. Here, we tested whether spatial variation in field insect herbivory is associated with the variation in plant quality by conducting a meta-analysis of 223 correlation coefficients between herbivory levels and the expression of selected plant traits. We found no overall correlation between herbivory and either concentrations of plant secondary metabolites or values of physical leaf traits. This result was due to both the large number of low correlations and the opposing directions of high correlations in individual studies. Field herbivory demonstrated a significant association only with nitrogen: herbivore pressure increased with an increase in nitrogen concentration in plant tissues. Thus, our meta-analysis does not support either theoretical prediction, i.e., that plants possess high antiherbivore defences in localities with high herbivore pressure or that herbivory is low in localities where plant defences are high. We conclude that information about putative plant defences is insufficient to predict plant losses to insects in field conditions and that the only bottom-up factor shaping spatial variation in insect herbivory is plant nutritive value. Our findings stress the need to improve a theory linking plant putative defences and herbivory.

Methoxyfuranocoumarins of Natural Origin-Updating Biological Activity Research and Searching for New Directions-A Review.

Plant secondary metabolites, including furanocoumarins, have attracted attention for decades as active molecules with therapeutic potential, especially those occurring in a limited number of species as evolutionarily specific and chemotaxonomically important. The most famous methoxyfuranocoumarins (MFCs), bergapten, xanthotoxin, isopimpinellin, phellopterin, byakangelicol, byakangelicin, isobergapten, pimpinellin, sphondin, as well as rare ones such as peucedanin and 8-methoxypeucedanin, apaensin, cnidilin, moellendorffiline and dahuribiethrins, have recently been investigated for their various biological activities. The α-glucosidase inhibitory activity and antioxidant potential of moellendorffiline, the antiproliferative and proapoptotic properties of non-UV-activated bergapten and xanthotoxin, the effect of MFC on the activity of tyrosinase, acetyl- and butylcholinesterase, and the role of these compounds as adjuvants in anticancer and antibacterial tests have been confirmed. The anticonvulsant effects of halfordin, the antidepressant effects of xanthotoxin, and the antiadipogenic, neuroprotective, anti-amyloid-ß, and anti-inflammatory (via increasing SIRT 1 protein expression) properties of phellopterin, as well as the activity of sphondin against hepatitis B virus, have also attracted interest. It is worth paying attention to the agonistic effect of xanthotoxin on bitter taste receptors (TAS2Rs) on cardiomyocytes, which may be important in the future treatment of tachycardia, as well as the significant anti-inflammatory activity of dahuribiethrins. It should be emphasized that MFCs, although in many cases isolated for the first time many years ago, are still of great interest as bioactive molecules. The aim of this review is to highlight key recent developments in the study of the diverse biological activities of MFCs and attempt to highlight promising directions for their further research. Where possible, descriptions of the mechanisms of action of MFC are provided, which is related to the constantly discovered therapeutic potential of these molecules. The review covers the results of experiments from the last ten years (2014-2023) conducted on isolated natural cMFCs and includes the activity of molecules that have not been activated by UV rays.

Revisiting Changes in Growth, Physiology and Stress Responses of Plants under the Effect of Enhanced CO2 and Temperature.

Climate change has universally affected the whole ecosystem in a unified manner and is known to have improbable effects on agricultural productivity and food security. Carbon dioxide (CO2) and temperature are the major environmental factors that have been shown to increase sharply during the last century and are directly responsible for affecting plant growth and development. A number of previous investigations have deliberated the positive effects of elevated CO2 on plant growth and development of various C3 crops, while detrimental effects of enhanced temperature on different crop plants like rice, wheat, maize and legumes are generally observed. A combined effect of elevated CO2 and temperature has yet to be studied in great detail; therefore, this review attempts to delineate the interactive effects of enhanced CO2 and temperature on plant growth, development, physiological and molecular responses. Elevated CO2 maintains leaf photosynthesis rate, respiration, transpiration and stomatal conductance in the presence of elevated temperature and sustains plant growth and productivity in the presence of both these environmental factors. Concomitantly, their interaction also affects the nutritional quality of seeds and leads to alterations in the composition of secondary metabolites. Elevated CO2 and temperature modulate phytohormone concentration in plants, and due to this fact, both environmental factors have substantial effects on abiotic and biotic stresses. Elevated CO2 and temperature have been shown to have mitigating effects on plants in the presence of other abiotic stress agents like drought and salinity, while no such pattern has been observed in the presence of biotic stress agents. This review focuses on the interactive effects of enhanced CO2 and temperature on different plants and is the first of its kind to deliver their combined responses in such detail.

Crystal structure of activating sulfotransferase SgdX2 involved in biosynthesis of secondary metabolite sungeidine.

Microorganisms synthesize a plethora of complex secondary metabolites, many of which are beneficial to human health, such as anticancer agents and antibiotics. Among these, the Sungeidines are a distinct class of secondary metabolites known for their bulky and intricate structures. They are produced by a specific biosynthetic gene cluster within the genome of the soil-dwelling actinomycete Micromonospora sp. MD118. A notable enzyme in the Sungeidine biosynthetic pathway is the activating sulfotransferase SgdX2. In this pathway, SgdX2 mediates a key sulfation step, after which the product undergoes spontaneous dehydration to yield a Sungeidine compound. To delineate the structural basis for SgdX2's substrate recognition and catalytic action, we have determined the crystal structure of SgdX2 in complex with its sulfate donor product, 3'-phosphoadenosine 5'-phosphate (PAP), at a resolution of 1.6 Å. Although SgdX2 presents a compact overall structure, its core elements are conserved among other activating sulfotransferases. Our structural analysis reveals a unique substrate-binding pocket that accommodates bulky, complex substrates, suggesting a specialized adaptation for Sungeidine synthesis. Moreover, we have constructed a substrate docking model that provides insights into the molecular interactions between SgdX2 and Sungeidine F, enhancing our understanding of the enzyme's specificity and catalytic mechanism. The model supports a general acid-base catalysis mechanism, akin to other sulfotransferases, and underscores the minor role of disordered regions in substrate recognition. This integrative study of crystallography and computational modeling advances our knowledge of microbial secondary metabolite biosynthesis and may facilitate the development of novel biotechnological applications.

Comprehensive genomic analysis of Burkholderia arboris PN-1 reveals its biocontrol potential against Fusarium solani-induced root rot in Panax notoginseng.

Panax notoginseng (Burkill) F.H. Chen, a valuable traditional Chinese medicine, faces significant yield and quality challenges stemming from root rot primarily caused by Fusarium solani. Burkholderia arboris PN-1, isolated from the rhizosphere soil of P. notoginseng, demonstrated a remarkable ability to inhibit the growth of F. solani. This study integrates phenotypic, phylogenetic, and genomic analyses to enhance our understanding of the biocontrol mechanisms employed by B. arboris PN-1. Phenotype analysis reveals that B. arboris PN-1 effectively suppresses P. notoginseng root rot both in vitro and in vivo. The genome of B. arboris PN-1 comprises three circular chromosomes (contig 1: 3,651,544 bp, contig 2: 1,355,460 bp, and contig 3: 3,471,056 bp), with a 66.81% GC content, housing 7,550 protein-coding genes. Notably, no plasmids were detected. Phylogenetic analysis places PN-1 in close relation to B. arboris AU14372, B. arboris LMG24066, and B. arboris MEC_B345. Average nucleotide identity (ANI) values confirm the PN-1 classification as B. arboris. Comparative analysis with seven other B. arboris strains identified 4,628 core genes in B. arboris PN-1. The pan-genome of B. arboris appears open but may approach closure. Whole-genome sequencing revealed 265 carbohydrate-active enzymes and identified 9 gene clusters encoding secondary metabolites. This comprehensive investigation enhances our understanding of B. arboris genomes, paving the way for their potential as effective biocontrol agents against fungal plant pathogens in the future.

Vineyard microclimate alterations induced by black inter-row mulch through transcriptome reshaped the flavoromics of cabernet sauvignon grapes.

BACKGROUND: Weed control is essential for agricultural floor management in vineyards and the inter-row mulching is an eco-friendly practice to inhibit weed growth via filtering out photosynthetically active radiation. Besides weed suppression, inter-row mulching can influence grapevine growth and the accumulation of metabolites in grape berries. However, the complex interaction of multiple factors in the field challenges the understanding of molecular mechanisms on the regulated metabolites. In the current study, black geotextile inter-row mulch (M) was applied for two vintages (2016-2017) from anthesis to harvest. Metabolomics and transcriptomics analysis were conducted in two vintages, aiming to provide insights into metabolic and molecular responses of Cabernet Sauvignon grapes to M in a semi-arid climate. RESULTS: Upregulation of genes related to photosynthesis and heat shock proteins confirmed that M weakened the total light exposure and grapes suffered heat stress, resulting in lower sugar-acid ratio at harvest. Key genes responsible for enhancements in phenylalanine, glutamine, ornithine, arginine, and C6 alcohol concentrations, and the downward trend in ε-viniferin, anthocyanins, flavonols, terpenes, and norisoprenoids in M grapes were identified. In addition, several modules significantly correlated with the metabolic biomarkers through weighted correlation network analysis, and the potential key transcription factors regulating the above metabolites including VviGATA11, VviHSFA6B, and VviWRKY03 were also identified. CONCLUSION: This study provides a valuable overview of metabolic and transcriptomic responses of M grapes in semi-arid climates, which could facilitate understanding the complex regulatory network of metabolites in response to microclimate changes.

Impact of silver nanoparticles on secondary metabolite composition and toxicity in anise (Pimpinella anisum L.) callus culture.

BACKGROUND: There are numerous challenges associated with producing desired amounts of secondary metabolites (SMs), which are mostly unique and cannot be chemically synthesized. Many studies indicate that nanoparticles (NPs) can boost the production of SMs. Still, the precise manner in which NPs induce metabolic changes remains unidentified. This study examines the influence of eco-friendly silver NPs (AgNPs) on the chemical makeup and toxicity of Pimpinella anisum L. (anise). RESULTS: AgNPs were introduced into anise callus cultures at different concentrations (0, 1.0, 5.0, 10, and 20 mg/L). The induced oxidative stress was tracked over intervals of 7, 14, 28, and 35 days. Chemical composition evaluations were carried out on the 35th day. Within the first 14 days, plant stress was evident, though the plant adapted to the stress later on. Notably, the plant showed high tolerance at 1 mg/L and 5 mg/L concentrations despite increased toxicity levels. However, relatively high toxicity levels were identified at 10 and 20 mg/L. The AgNP-induced stress significantly impacted anise SMs, particularly affecting fatty acid content. In the 10 and 20 mg/L AgNP groups, essential metabolites, including palmitic and linoleic acid, showed a significant increase. Polyunsaturated (omega) and monounsaturated fatty acids, vital for the food and pharmaceutical industries, saw substantial growth in the 1 and 5 mg/L AgNP groups. For the first time, vanillyl alcohol and 4-Hydroxybenzoic acid were detected along with various phenolic compounds, such as t-anethole, Salicylic acid, and Thiamazole. CONCLUSION: AgNPs can function as an elicitor to efficiently generate essential SMs such as omegas and phenolic compounds in anise callus culture. This study explores the application of AgNPs as plant elicitors in anise SM production, offering invaluable insight into potential uses.

A comparison between the role of enniatins and deoxynivalenol in Fusarium virulence on different tissues of common wheat.

BACKGROUND: Fusarium graminearum and Fusarium avenaceum are two of the most important causal agents of Fusarium head blight (FHB) of wheat. They can produce mycotoxins that accumulate in infected wheat heads, including deoxynivalenol (DON) and enniatins (ENNs), produced by F. graminearum and F. avenaceum, respectively. While the role of DON as a virulence factor in F. graminearum toward wheat is well known, ENNs in F. avenaceum has been poorly explored. Results obtained to-date indicate that ENNs may confer an advantage to F. avenaceum only on particular hosts. RESULTS: In this study, with the use of ENN-producing and ENN non-producing F. avenaceum strains, the role of ENNs on F. avenaceum virulence was investigated on the root, stem base and head of common wheat, and compared with the role of DON, using DON-producing and DON non-producing F. graminearum strains. The DON-producing F. graminearum strain showed a significantly higher ability to cause symptoms and colonise each of the tested tissues than the non-producing strain. On the other hand, the ability to produce ENNs increased initial symptoms of the disease and fungal biomass accumulation, measured by qPCR, only in wheat heads, and not in roots or stem bases. LC-MS/MS analysis was used to confirm the presence of ENNs and DON in the different strains, and results, both in vitro and in wheat heads, were consistent with the genetics of each strain. CONCLUSION: While the key role of DON on F. graminearum virulence towards three different wheat tissues was noticeable, ENNs seemed to have a role only in influencing F. avenaceum virulence on common wheat heads probably due to an initial delay in the appearance of symptoms.

Exogenous application of sulfur-rich thiourea (STU) to alleviate the adverse effects of cobalt stress in wheat.

Heavy metal stress affects crop growth and yields as wheat (Triticum aestivum L.) growth and development are negatively affected under heavy metal stress. The study examined the effect of cobalt chloride (CoCl2) stress on wheat growth and development. To alleviate this problem, a pot experiment was done to analyze the role of sulfur-rich thiourea (STU) in accelerating the defense system of wheat plants against cobalt toxicity. The experimental treatments were, i) Heavy metal stress (a) control and (b) Cobalt stress (300 µM), ii) STU foliar applications; (a) control and (b) 500 µM single dose was applied after seven days of stress, and iii) Wheat varieties (a) FSD-2008 and (b) Zincol-2016. The results revealed that cobalt stress decreased chlorophyll a by 10%, chlorophyll b by 16%, and carotenoids by 5% while foliar application of STU increased these photosynthetic pigments by 16%, 15%, and 15% respectively under stress conditions as in contrast to control. In addition, cobalt stress enhances hydrogen peroxide production by 11% and malondialdehyde (MDA) by 10%. In comparison, STU applications at 500 µM reduced the production of these reactive oxygen species by 5% and by 20% by up-regulating the activities of antioxidants. Results have revealed that the activities of SOD improved by 29%, POD by 25%, and CAT by 28% under Cobalt stress. Furthermore, the foliar application of STU significantly increased the accumulation of osmoprotectants as TSS was increased by 23% and proline was increased by 24% under cobalt stress. Among wheat varieties, FSD-2008 showed better adaptation under Cobalt stress by showing enhanced photosynthetic pigments and antioxidant activities compared to Zincol-2016. In conclusion, the foliar-applied STU can alleviate the negative impacts of Cobalt stress by improving plant physiological attributes and upregulating the antioxidant defense system in wheat.