Nutrient-deficient Conditions Research Articles

Role of vaccinia virus growth factor in stimulating the mTORC1-CAD axis of the de novo pyrimidine pathway under different nutritional cues.

Our research provides new insights into how VACV alters the mTORC1-CAD signaling axis under different nutritional cues. The identification of how VACV regulates a major enzyme, CAD, within the de novo pyrimidine synthesis pathway, establishes a molecular mechanism for determining how VACV reshapes this essential pathway, necessary for facilitating efficient VACV replication. We further emphasize that, despite nutrient-poor conditions, which typically inhibit mTORC1 activation, VACV can stimulate mTORC1. We identify its early growth factor, VGF, as an important factor for this stimulation of mTORC1 and its downstream effector CAD, revealing a new mechanism for how VACV sustains mTORC1-CAD axis activation under these nutrient deficient conditions. This work provides fresh insights into the molecular mechanisms of mTORC1-CAD regulation, which has the potential to be utilized to enhance VACV as an oncolytic tool, vaccine vector and aid in the development of antiviral drugs.

Using multi-omics to explore the effect of Bacillus velezensis SAAS-63 on resisting nutrient stress in lettuce

To avoid the unreasonable use of chemical fertilizer, an environmentally friendly means of improving soil fertility is required. This study explored the role of the plant growth-promoting rhizosphere bacteria (PGPR) strain Bacillus velezensis SAAS-63 in improving nutrient stress in lettuce. Compared with no inoculation, B. velezensis SAAS-63 inoculants exhibited significantly increased fresh weight, root length, and shoot height under nutrient deficiency, as well as improved antioxidant activities and proline contents. The exogenous addition of B. velezensis SAAS-63 also significantly increased the accumulation of macroelements and micronutrients in lettuce. To elucidate the resistance mechanisms induced by B. velezensis SAAS-63 under nutrient stress, high-throughput sequencing and multi-omics analysis were performed. Inoculation with B. velezensis SAAS-63 altered the microbial community of the rhizosphere and increased the relative abundances of Streptomyces, Actinoallomurus, Verrucomicrobia, and Chloroflexi. It is worth noting that the inoculant SAAS-63 can affect plant rhizosphere metabolism. The inoculant changed the metabolic flow of phenylpropanoid metabolic pathway under nutrient deficiency and promoted phenylalanine to participate more in the synthesis of lignin precursors and coumarin substances by inhibiting the synthesis of flavone and isoflavone, thus improving plant resistance. This study showed that the addition of inoculant SAAS-63 could help plants recruit microorganisms to decompose and utilize trehalose and re-established the carbon metabolism of the plant rhizosphere. Additionally, microbes were found to be closely related to the accumulation of metabolites based on correlation analysis. The results indicated that the addition of PGPRs has an important role in regulating soil rhizosphere microbes and metabolism, providing valuable information for understanding how PGPRs affect complex biological processes and enhance plant adaptation to nutrient deficiency.Key points• Inoculation with SAAS-63 significantly promoted plant growth under nutrient-deficient conditions• Inoculation with SAAS-63 affected rhizosphere microbial diversity and community structure• Inoculation with SAAS-63 affected plant rhizosphere metabolism and induced plants to synthesize substances that resist stressGraphical abstract

Maize functional requirements drive the selection of rhizobacteria under long-term fertilization practices.

Rhizosphere microbiomes are pivotal for crop fitness, but the principles underlying microbial assembly during root-soil interactions across soils with different nutrient statuses remain elusive. We examined the microbiomes in the rhizosphere and bulk soils of maize plants grown under six long-term (≥ 29 yr) fertilization experiments in three soil types across middle temperate to subtropical zones. The assembly of rhizosphere microbial communities was primarily driven by deterministic processes. Plant selection interacted with soil types and fertilization regimes to shape the structure and function of rhizosphere microbiomes. Predictive functional profiling showed that, to adapt to nutrient-deficient conditions, maize recruited more rhizobacteria involved in nutrient availability from bulk soil, although these functions were performed by different species. Metagenomic analyses confirmed that the number of significantly enriched Kyoto Encyclopedia of Genes and Genomes Orthology functional categories in the rhizosphere microbial community was significantly higher without fertilization than with fertilization. Notably, some key genes involved in carbon, nitrogen, and phosphorus cycling and purine metabolism were dominantly enriched in the rhizosphere soil without fertilizer input. In conclusion, our results show that maize selects microbes at the root-soil interface based on microbial functional traits beneficial to its own performance, rather than selecting particular species.

Anaerobic dihydrogen consumption of nutrient-limited aquifer sediment microbial communities examined by stable isotope analysis

ABSTRACT The biogeochemical consequences of dihydrogen (H2) underground storage in porous aquifers are poorly understood. Here, the effects of nutrient limitations on anaerobic H2 oxidation of an aquifer microbial community in sediment microcosms were determined in order to evaluate possible responses to high H2 partial pressures. Hydrogen isotope analyses of H2 yielded isotope depletion in all biotic setups indicating microbial H2 consumption. Carbon isotope analyses of carbon dioxide (CO2) showed isotope enrichment in all H2-supplemented biotic setups indicating H2-dependent consumption of CO2 by methanogens or homoacetogens. Homoacetogenesis was indicated by the detection of acetate and formate. Consumption of CO2 and H2 varied along the differently nutrient-amended setups, as did the onset of methane production. Plotting carbon against hydrogen isotope signatures of CH4 indicated that CH4 was produced hydrogenotrophically and fermentatively. The putative hydrogenotrophic Methanobacterium sp. was the dominant methanogen. Most abundant phylotypes belonged to typical ferric iron reducers, indicating that besides CO2, Fe(III) was an important electron acceptor. In summary, our study provides evidence for the adaptability of subsurface microbial communities under different nutrient-deficient conditions to elevated H2 partial pressures.

Paenibacillus lentimorbus alleviates nutrient deficiency-induced stress in Zea mays by modulating root system architecture, auxin signaling, and metabolic pathways.

Paenibacillus lentimorbus reprograms auxin signaling and metabolic pathways for modulating root system architecture to mitigate nutrient deficiency in maize crops. The arable land across the world is having deficiency and disproportionate nutrients, limiting crop productivity. In this study, the potential of plant growth-promoting rhizobacteria (PGPR) viz., Pseudomonas putida, Paenibacillus lentimorbus, and their consortium was explored for growth promotion in maize (Zea mays) under nutrient-deficient conditions. PGPR inoculation improved the overall health of plants under nutrient-deficient conditions. The PGPR inoculation significantly improved the root system architecture and also induced changes in root cortical aerenchyma. Based on plant growth and physiological parameters inoculation with P. lentimorbus performed better as compared to P. putida, consortium, and uninoculated control. Furthermore, expression of auxin signaling (rum1, rul1, lrp1, rtcs, rtcl) and root hair development (rth)-related genes modulated the root development process to improve nutrient acquisition and tolerance to nutrient-deficient conditions in P. lentimorbus inoculated maize plants. Further, GC-MS analysis indicated the involvement of metabolites including carbohydrates and organic acids due to the interaction between maize roots and P. lentimorbus under nutrient-deficient conditions. These findings affirm that P. lentimorbus enhance overall plant growth by modulating the root system of maize to provide better tolerance to nutrient-deficient condition.

Transcriptomic and metabolomic responses to varying nutrient conditions reveal new insights into pitcher formation in Nepenthes khasiana.

Nepenthes are carnivorous plants that colonize habitats poor in soil nutrients. To survive, Nepenthes develop pitchers capable of capturing and digesting attracted prey. Prey-derived nutrients are then absorbed to support plant growth and reproduction. So far, pitcher formation in Nepenthes is a poorly understood biological process. To shed light on the formation of Nepenthes pitchers, we grew dissected shoot apices of 3-month-old N. khasiana seedlings in Murashige and Skoog (MS) medium of varying strengths viz. full-strength MS (1 MS), quarter-strength MS (1/4 MS), and one-eighth strength MS (1/8 MS), including those lacking nitrogen (N), phosphorus (P), and potassium (K) and in the presence of N-1-naphthylphthalamic acid (NPA). We sequenced the transcriptome and performed gas chromatography-mass spectrometry to determine changes in gene expression patterns and primary metabolite accumulations in response to the varying nutrient conditions. Shoots grown in 1 MS or NPA-containing 1/4 MS and 1/8 MS failed to develop pitchers. Remarkably, pitcher formation is restored when N was removed from 1 MS. Transcriptomic response to nutrient-sufficient and nutrient-deficient conditions are associated with the enrichment of several defence-related genes, including two JA-mediated defence response genes, WRKY51 and WRKY11, respectively. Further, metabolomic response to the varying nutrient conditions identifies glutamic acid as a key metabolite, accumulating at lower and higher levels in shoots with and without pitchers, respectively. Together, our findings suggest that failure to form pitchers may be associated with the suppression of the JA-signalling pathway, whereas the induction of the JA-mediated defence response is linked to pitcher formation in N. khasiana.

Strigolactone GR24-mediated mitigation of phosphorus deficiency through mycorrhization in aerobic rice

Strigolactones (SLs) are a new class of plant hormones that play a significant role in regulating various aspects of plant growth promotion, stress tolerance and influence the rhizospheric microbiome. GR24 is a synthetic SL analog used in scientific research to understand the effects of SL on plants and to act as a plant growth promoter. This study aimed to conduct hormonal seed priming at different concentrations of GR24 (0.1, 0.5, 1.0, 5.0 and 10.0 µM with and without arbuscular mycorrhizal fungi (AMF) inoculation in selected aerobic rice varieties (CR Dhan 201, CR Dhan 204, CR Dhan 205, and CR Dhan 207), Kasalath-IC459373 (P-tolerant check), and IR-36 (P-susceptible check) under phosphorus (P)-deficient conditions to understand the enhancement of growth and priming effects in mycorrhization. Our findings showed that seed priming with 5.0 µM SL GR24 enhanced the performance of mycorrhization in CR Dhan 205 (88.91 %), followed by CR Dhan 204 and 207, and AMF sporulation in CR Dhan 201 (31.98 spores / 10 gm soil) and CR Dhan 207 (30.29 spores / 10 g soil), as well as rice growth. The study showed that the highly responsive variety CR Dhan 207 followed by CR Dhan 204, 205, 201, and Kasalath IC459373 showed higher P uptake than the control, and AMF treated with 5.0 µM SL GR24 varieties CR Dhan 205 followed by CR Dhan 207 and 204 showed the best performance in plant growth, chlorophyll content, and soil functional properties, such as acid and alkaline phosphatase activity, soil microbial biomass carbon (MBC), dehydrogenase activity (DHA), and fluorescein diacetate activity (FDA). Overall, AMF intervention with SL GR24 significantly increased plant growth, soil enzyme activity, and uptake of P compared to the control. Under P-deficient conditions, seed priming with 5.0 µM strigolactone GR24 and AMF inoculum significantly increased selected aerobic rice growth, P uptake, and soil enzyme activities. Application of SLs formulations with AMF inoculum in selected aerobic rice varieties, CR Dhan 207, CR Dhan 204, and CR Dhan 205, will play an important role in mycorrhization, growth, and enhancement of P utilization under P- nutrient deficient conditions.

The role of transglutaminase 2 in regulation of the balance between autophagy and apoptosis in tumor cells

In normal tissue, cellular homeostasis is largely driven by two catabolic pathways: apoptosis and autophagy. Apoptosis, or programmed cell death, is regulated by pro-apoptotic factors, and promotes the removal of problematic cells. Autophagy, which in turn includes three forms: macro-, micro-, and chaperone-mediated autophagy, can promote both cell survival by selectively removing potentially apoptosis-inducing factors and raising the threshold of stress required for the induction of cell death. Recently, evidence has been accumulating suggesting the existence of common molecular pathways between autophagy and apoptosis, as well as the influence of the extracellular matrix on these processes. One of the important enzymes involved in the coordination and regulation of these processes is transglutaminase 2 (TG2). Different types of TG2 activities are involved in maintaining the dynamic balance between extracellular matrix and intracellular autophagy/apoptosis processes, while dysregulation of these processes may contribute to the pathogenesis of various human diseases, including oncogenesis. For example, TG2 can promote the degradation of pro-apoptotic proteins and the survival of renal cell carcinoma cells under nutrient-deficient conditions by modulating the autophagy process. In cells of various tissues deprived of TG2, aggregates of ubiquitinated proteins and damaged mitochondria are observed, which in turn induces proteotoxic stress and cell death. conversely, the transamidase activity of TG2 was observed to inhibit anti-apoptotic signaling in a human leukemic monocytic lymphoma model. In the present review, a number of important functions of TG2 in oncogenesis are described, along with the dual role of TG2 in modulating such opposite processes as cell survival and cell death.

Dynamic transcriptome analysis unravels key regulatory genes of maize root growth and development in response to potassium deficiency

Main conclusionIntegrated root phenotypes and transcriptome analysis have revealed key candidate genes responsible for maize root growth and development in potassium deficiency.Potassium (K) is a vital macronutrient for plant growth, but our understanding of its regulatory mechanisms in maize root system architecture (RSA) and K+ uptake remains limited. To address this, we conducted hydroponic and field trials at different growth stages. K+ deficiency significantly inhibited maize root growth, with metrics like total root length, primary root length, width and maximum root number reduced by 50% to 80% during early seedling stages. In the field, RSA traits exhibited maximum values at the silking stage but continued to decline thereafter. Furthermore, K deprivation had a pronounced negative impact on root morphology and RSA growth and grain yield. RNA-Seq analysis identified 5972 differentially expressed genes (DEGs), including 17 associated with K+ signaling, transcription factors, and transporters. Weighted gene co-expression network analysis revealed 23 co-expressed modules, with enrichment of transcription factors at different developmental stages under K deficiency. Several DEGs and transcription factors were predicted as potential candidate genes responsible for maize root growth and development. Interestingly, some of these genes exhibited homology to well-known regulators of root architecture or development in Arabidopsis, such as Zm00001d014467 (AtRCI3), Zm00001d011237 (AtWRKY9), and Zm00001d030862 (AtAP2/ERF). Identifying these key genes helps to provide a deeper understanding of the molecular mechanisms governing maize root growth and development under nutrient deficient conditions offering potential benefits for enhancing maize production and improving stress resistance through targeted manipulation of RSA traits in modern breeding efforts.

Constitutive basis of root system architecture: uncovering a promising trait for breeding nutrient- and drought-resilient crops

Root system architecture (RSA) plays a pivotal role in efficient uptake of essential nutrients, such as phosphorous (P), nitrogen (N), and water. In soils with heterogeneous nutrient distribution, root plasticity can optimize acquisition and plant growth. Here, we present evidence that a constitutive RSA can confer benefits for sorghum grown under both sufficient and limiting growth conditions. Our studies, using P efficient SC103 and inefficient BTx635 sorghum cultivars, identified significant differences in root traits, with SC103 developing a larger root system with more and longer lateral roots, and enhanced shoot biomass, under both nutrient sufficient and deficient conditions. In addition to this constitutive attribute, under P deficiency, both cultivars exhibited an initial increase in lateral root development; however, SC103 still maintained the larger root biomass. Although N deficiency and drought stress inhibited both root and shoot growth, for both sorghum cultivars, SC103 again maintained the better performance. These findings reveal that SC103, a P efficient sorghum cultivar, also exhibited enhanced growth performance under N deficiency and drought. Our results provide evidence that this constitutive nature of RSA can provide an avenue for breeding nutrient- and drought-resilient crops.

RUNDC1 inhibits autolysosome formation and survival of zebrafish via clasping ATG14-STX17-SNAP29 complex.

Autophagy serves as a pro-survival mechanism for a cell or a whole organism to cope with nutrient stress. Our understanding of the molecular regulation of this fusion event remains incomplete. Here, we identified RUNDC1 as a novel ATG14-interacting protein, which is highly conserved across vertebrates, including zebrafish and humans. By gain and loss of function studies, we demonstrate that RUNDC1 negatively modulates autophagy by blocking fusion between autophagosomes and lysosomes via inhibiting the assembly of the STX17-SNAP29-VAMP8 complex both in human cells and the zebrafish model. Moreover, RUNDC1 clasps the ATG14-STX17-SNAP29 complex via stimulating ATG14 homo-oligomerization to inhibit ATG14 dissociation. This also prevents VAMP8 from binding to STX17-SNAP29. We further identified that phosphorylation of RUNDC1 Ser379 is crucial to inhibit the assembly of the STX17-SNAP29-VAMP8 complex via promoting ATG14 homo-oligomerization. In line with our findings, RunDC1 is crucial for zebrafish in their response to nutrient-deficient conditions. Taken together, our findings demonstrate that RUNDC1 is a negative regulator of autophagy that restricts autophagosome fusion with lysosomes by clasping the ATG14-STX17-SNAP29 complex to hinder VAMP8 binding.

The role of AJB35136 and fdtA genes in biofilm formation by avian pathogenic Escherichia coli

BackgroundInfections caused by avian pathogenic Escherichia coli (APEC) result in significant economic losses in poultry industry. APEC strains are known to form biofilms in various conditions allowing them to thrive even under harsh and nutrient-deficient conditions on different surfaces, and this ability enables them to evade chemical and biological eradication methods. Despite knowing the whole genome sequences of various APEC isolates, little has been reported regarding their biofilm-associated genes. A random transposon mutant library of the wild-type APEC IMT 5155 comprising 1,300 mutants was analyzed for biofilm formation under nutrient deprived conditions using Videoscan technology coupled with fluorescence microscopy. Seven transposon mutants were found to have reproducibly and significantly altered biofilm formation and their mutated genes were identified by arbitrary PCR and DNA sequencing. The intact genes were acquired from the wild-type strain, cloned in pACYC177 plasmid and transformed into the respective altered biofilm forming transposon mutants, and the biofilm formation was checked in comparison to the wild type and mutant strains under the same conditions.ResultsIn this study, we report seven genes i.e., nhaA, fdeC, yjhB, lysU, ecpR, AJB35136 and fdtA of APEC with significant contribution to biofilm formation. Reintroduction of AJB35136 and fdtA, reversed the altered phenotype proving that a significant role being played by these two O-antigen related genes in APEC biofilm formation. Presence of these seven genes across nonpathogenic E. coli and APEC genomes was also analyzed showing that they are more prevalent in the latter.ConclusionsThe study has elucidated the role of these genes in APEC biofilm formation and compared them to adhesion expanding the knowledge and understanding of the economically significant pathogens.

Three consecutive cytosolic glycolysis enzymes modulate autophagic flux.

Autophagy serves as an important recycling route for the growth and survival of eukaryotic organisms in nutrient-deficient conditions. Since starvation induces massive changes in metabolic flux that are coordinated by key metabolic enzymes, specific processing steps of autophagy may be linked with metabolic flux-monitoring enzymes. We attempted to identify carbon metabolic genes that modulate autophagy using VIGS screening of 45 glycolysis- and Calvin-Benson cycle-related genes in Arabidopsis (Arabidopsis thaliana). Here, we report that three consecutive triose-phosphate-processing enzymes involved in cytosolic glycolysis, TPI (triose-phosphate-isomerase), GAPC (glyceraldehyde-3-phosphate dehydrogenase), and PGK (phosphoglycerate kinase), designated TGP, negatively regulate autophagy. Depletion of TGP enzymes causes spontaneous autophagy induction and increases AUTOPHAGY-RELATED 1 (ATG1) kinase activity. TGP enzymes interact with ATG101, a regulatory component of the ATG1 kinase complex. Spontaneous autophagy induction and abnormal growth under insufficient sugar in the TGP mutants are suppressed by crossing with the atg101 mutant. Considering that triose-phosphates are photosynthates transported to the cytosol from active chloroplasts, the TGP enzymes would be strategically positioned to monitor the flow of photosynthetic sugars and modulate autophagy accordingly. Collectively, these results suggest that TGP enzymes negatively control autophagy acting upstream of the ATG1 complex, which is critical for seedling development.

Biomass-derived carbon dots with light conversion and nutrient provisioning capabilities facilitate plant photosynthesis

Carbon dots (CDs)-enabled agriculture has been developing rapidly, but small-scale synthesis and high costs hinder the agricultural application of CDs. Herein, biomass-derived carbon dots (B-CDs) were prepared on a gram-level with low cost, and these B-CDs significantly improved crop photosynthesis. The B-CDs, exhibiting small size and blue fluorescence, were absorbed by crops and enhanced photosynthesis via light-harvesting. Foliar application of B-CDs (10 mg·kg−1) could promote chlorophyll synthesis (30–100 %), Ferredoxin (Fd, 40–80 %), Rubisco enzyme (20–110 %) and upregulated gene expression (20–70 %), resulting in higher net photosynthetic rates (130–300 %), dry biomass (160–300 %) and fresh biomass (80–150 %). Further, the B-CDs could increase crop photosynthesis under nutrient deficient conditions, which was attributed to the release of nutrients from B-CDs. Therefore, the B-CDs enhanced the photosynthesis via enhancing light conversion and nutrient supply. This study provides a promising material capable of enhancing photosynthesis for sustainable agriculture production.

How influential is the role of oligotrophication on the integrity of fish assemblages in the littoral zone?

Food web theory predicts that one of the consequences of oligotrophication is the decline in fisheries following the establishment of nutrient-deficient conditions and low biogenic production. However, emerging evidence suggests that more complex trophic interactions, induced by plankton composition, dietary diversification, temporal and spatial heterogeneity, variations in fish age and size structure can lead to ecosystem responses that deviate from theoretical predictions; especially in the shallow littoral zone. In this study, two end-to-end modelling strategies are used to characterize potential food web structural shifts and overall ecosystem productivity in response to oligotrophication. Our modelling strategy draws upon empirical and theoretical evidence from the Bay of Quinte, a semi-enclosed embayment in northeastern Lake Ontario that has been subjected to phosphorus (P) abatement strategies in the 1970s. We first show that the role of food abundance has been a primary factor shaping fish production, but the fish community gradually responded to the reduced availability of pelagic staples of their diet by displaying greater reliance upon alternative sources, including benthic and other autochthonous (or even allochthonous) food items. Our analysis further suggests that degree of diet overlap between competing trophic guilds can significantly modulate realized biomass levels. The composition of the autotrophic community is another major confounding factor that can induce significant variations from the predicted food web productivity patterns in response to oligotrophication. Overall, our analysis suggests that the proposed reduction of the ambient total phosphorus levels may not necessarily trigger a significant decline in fish biomass in the Bay of Quinte.

Poly(3-hydroxybutyrate) Degradation by Bacillus infantis sp. Isolated from Soil and Identification of phaZ and bdhA Expressing PHB Depolymerase.

Poly(3-hydroxybutyrate) (PHB) is a biodegradable and biocompatible bioplastic. Effective PHB degradation in nutrient-poor environments is required for industrial and practical applications of PHB. To screen for PHB-degrading strains, PHB double-layer plates were prepared and three new Bacillus infantis species with PHB-degrading ability were isolated from the soil. In addition, phaZ and bdhA of all isolated B. infantis were confirmed using a Bacillus sp. universal primer set and established polymerase chain reaction conditions. To evaluate the effective PHB degradation ability under nutrient-deficient conditions, PHB film degradation was performed in mineral medium, resulting in a PHB degradation rate of 98.71% for B. infantis PD3, which was confirmed in 5 d. Physical changes in the degraded PHB films were analyzed. The decrease in molecular weight due to biodegradation was confirmed using gel permeation chromatography and surface erosion of the PHB film was observed using scanning electron microscopy. To the best of our knowledge, this is the first study on B. infantis showing its excellent PHB degradation ability and is expected to contribute to PHB commercialization and industrial composting.

Counteracting action of Bacillus stratosphericus and Staphylococcus succinus strains against deleterious salt effects on Zea mays L.

The salinization of soil is the process of progressive accumulation of salts such as sulfates, sodium, or chlorides into the soil. The increased level of salt has significant effects on glycophyte plants, such as rice, maize, and wheat, which are staple foods for the world's population. Consequently, it is important to develop biotechnologies that improve crops and clean up the soil. Among other remediation methods, there is an environmentally friendly approach to ameliorate the cultivation of glycophyte plants in saline soil, namely, the use of microorganisms tolerant to salt with growth-promoting features. Plant growth-promoting rhizobacteria (PGPR) can improve plant growth by colonizing their roots and playing a vital role in helping plants to establish and grow in nutrient-deficient conditions. Our research aimed to test in vivo halotolerant PGPR, isolated and characterized in vitro in a previous study conducted in our laboratory, inoculating them on maize seedlings to improve their growth in the presence of sodium chloride. The bacterial inoculation was performed using the seed-coating method, and the produced effects were evaluated by morphometric analysis, quantization of ion contents (sodium, potassium), produced biomass, both for epigeal (shoot) and hypogeal (root) organs, and by measuring salt-induced oxidative damage. The results showed an increase in biomass and sodium tolerance and even a reduction of oxidative stress in seedlings pretreated with a PGPR bacterial consortium (Staphylococcus succinus + Bacillus stratosphericus) over the control. Moreover, we observed that salt reduces growth and alters root system traits of maize seedlings, while bacterial treatment improves plant growth and partially restores the root architecture system in saline stress conditions. Therefore, the PGPR seed-coating or seedling treatment could be an effective strategy to enhance sustainable agriculture in saline soils due to the protection of the plants from their inhibitory effect.

Transcriptional Regulation of Autophagy-Related Genes by Sin3 Negatively Modulates Autophagy in Magnaporthe oryzae.

Autophagy is a conserved degradation and recycling pathway in eukaryotes and is important for their normal growth and development. An appropriate status of autophagy is crucial for organisms which is tightly regulated both temporally and continuously. Transcriptional regulation of autophagy-related genes (ATGs) is an important layer in autophagy regulation. However, the transcriptional regulators and their mechanisms are still unclear, especially in fungal pathogens. Here, we identified Sin3, a component of the histone deacetylase complex, as a transcriptional repressor of ATGs and negative regulator of autophagy induction in the rice fungal pathogen Magnaporthe oryzae. A loss of SIN3 resulted in upregulated expression of ATGs and promoted autophagy with an increased number of autophagosomes under normal growth conditions. Furthermore, we found that Sin3 negatively regulated the transcription of ATG1, ATG13, and ATG17 through direct occupancy and changed levels of histone acetylation. Under nutrient-deficient conditions, the transcription of SIN3 was downregulated, and the reduced occupancy of Sin3 from those ATGs resulted in histone hyperacetylation and activated their transcription and in turn promoted autophagy. Thus, our study uncovers a new mechanism of Sin3 in modulating autophagy through transcriptional regulation. IMPORTANCE Autophagy is an evolutionarily conserved metabolic process and is required for the growth and pathogenicity of phytopathogenic fungi. The transcriptional regulators and precise mechanisms of regulating autophagy, as well as whether the induction or repression of ATGs is associated with autophagy level, are still poorly understood in M. oryzae. In this study, we revealed that Sin3 acts as a transcriptional repressor of ATGs to negatively regulate autophagy level in M. oryzae. Under the nutrient-rich conditions, Sin3 inhibits autophagy with a basal level through directly repressing the transcription of ATG1-ATG13-ATG17. Upon nutrient-deficient treatment, the transcriptional level of SIN3 would decrease and dissociation of Sin3 from those ATGs associates with histone hyperacetylation and activates their transcriptional expression and in turn contributes to autophagy induction. Our findings are important as we uncover a new mechanism of Sin3 for the first time to negatively modulate autophagy at the transcriptional level in M. oryzae.

High productivity of fucoxanthin and eicosapentaenoic acid in a marine diatom Chaetoceros gracilis by perfusion culture under high irradiance

For a high production rate of microalgae, a high-cell-density culture is an effective strategy for reducing the light intensity per dry weight in the culture to avoid photoinhibition under high light conditions. However, under high cell density microalgae are exposed to nutrient-deficient conditions, resulting in a reduced biomass production rate. To enhance the production rate of high-value bioactives such as fucoxanthin and eicosatetraenoic acid (EPA) by the diatom Chaetoceros gracilis, a perfusion culture was operated at harvesting rates of 10–40 % under light intensities of 300–2000 μmol m−2 s−1. At a harvesting rate of 20 % under a high light intensity of 2000 μmol m−2 s−1, the dry weight increased, and the areal productivity reached 15.6 ± 1.3 g-dry weight (dw) m−2 d−1, which is comparable to the maximum value previously reported in diatoms. The high biomass production, even at a low harvesting rate of 20 %, could result from sufficient nutrient supply by perfusion culture. At a harvesting rate of 20 %, the EPA areal productivity achieved 183 mg-dw m−2 d−1 even under 2000 μmol m−2 s−1 due to the increase in the dry weight using the perfusion culture. However, the fucoxanthin content decreased under 2000 μmol m−2 s−1. A strong relationship was observed between the specific light intensity per dry weight and fucoxanthin content in C. gracilis. This relationship indicates that the fucoxanthin content does not increase unless the specific light intensity per dry weight is adjusted below 20 μmol g-dw−1 s−1. Thus, perfusion culture proved to be useful to control the biomass-specific light intensity for the effective production of EPA and fucoxanthin in C. gracilis under high light conditions expected for outdoor culture.

Discovery of decreased ferroptosis in male colorectal cancer patients with KRAS mutations

Aberrant tumor metabolism is a hallmark of cancer in which metabolic rewiring can support tumor growth under nutrient deficient conditions. KRAS mutations occur in 35–45% of all colorectal cancer (CRC) cases and are difficult to treat. The relationship between mutant KRAS and aberrant metabolism in CRCs has not been fully explored and could be a target for intervention. We previously acquired non-targeted metabolomics data from 161 tumor tissues and 39 normal colon tissues from stage I-III chemotherapy naïve CRC patients. In this study, we revealed that only in male patients, tumors with KRAS mutations had several altered pathways that suppress ferroptosis, including glutathione biosynthesis, transsulfuration activity, and methionine metabolism. To validate this phenotype, MC38 CRC cells (KRASG13R) were treated with a ferroptosis inducer; RAS-selected lethal (RSL3). RSL3 altered metabolic pathways in the opposite direction to that seen in KRAS mutant tumors from male patients confirming a suppressed ferroptosis metabolic phenotype in these patients. We further validated gene expression data from an additional CRC patient cohort (Gene Expression Omnibus (GEO)), and similarly observed differences in ferroptosis-related genes by sex and KRAS status. Further examination of the relationship between these genes and overall survival (OS) in the GEO cohort showed that KRAS mutant tumors are associated with poorer 5-year OS compared to KRAS wild type tumors, and only in male patients. Additionally, high compared to low expression of GPX4, FTH1, FTL, which suppress ferroptosis, were associated with poorer 5-year OS only in KRAS mutant tumors from male CRC patients. Additionally, low compared to high expression of ACSL4 was associated with poorer OS for this group. Our results show that KRAS mutant tumors from male CRC patients have suppressed ferroptosis, and gene expression changes that suppress ferroptosis associate with adverse outcomes for these patients, revealing a novel potential avenue for therapeutic approaches.