Glucose Accumulation Research Articles

Water deficit drip irrigation promotes citrus sugar accumulation during the late growth stages

Water deficit drip irrigation (WDDI) in citrus orchards was found has a positive effect on fruit quality, particularly enhancing the soluble sugar content during the late period of fruit growth. However, the underlying molecular mechanism remains unclear. In this study, four deficit irrigation levels of D-60%, D-45%, D-30%, and D-15% were set at fruit expansion stage (stage III) and maturation stage (stage IV), respectively, and a fully irrigated treatment was set as the control (CK). Combined analysis of metabolomics and transcriptomics was used to reveal the molecular mechanism of sugar accumulation changes under different water deficit (WD) treatments. The results showed that sugar metabolism was growth stage dependent: stage III is a key period of sucrose metabolism and synthesis, while for stage IV, the accumulation of glucose and fructose increased significantly. Importantly, III-D15% and IV-D30% treatments were identified as optimal strategies for enhancing sugar content of citrus fruits. WDDI during the late growth stages up-regulated the expression of sugar metabolism-related differential expression genes (DEGs), consequently increasing the content of sugar-related differential expression metabolites (DEMs), and ultimately enhancing sugar accumulation in citrus fruits. For III-D15% treatment, DEMs related to sugar metabolism were mainly enriched in ‘carbon metabolism’, with significant increases in Sucrose, ɑ-D-Glucose-6 P and ß-D-Fructose-6 P content observed. SPS showed significant up-regulation, wihle BGLU, GN, TPS11, TPPF and TPPJ were down-regulated. For IV-D30% treatment, most DEMs were significantly enriched in ‘Glycolysis/Gluconeogenesis’. Key DEMs (Sucrose, D-Glucose-6 P, ß-D-Fructose-6 P) and DEGs (SUS, SPS, BGLU, HXK) involved in the metabolism and synthesis of sucrose, fructose and glucose were significantly increased. This study sheds light on the molecular mechanisms of sugar accumulation in citrus fruit under appropriate WDDI, providing valuable guidance for high-quality fruit production.

Deletion of the sugar importer gene OsSWEET1b accelerates sugar starvation-promoted leaf senescence in rice.

Leaf senescence is a combined response of plant cells stimulated by internal and external signals. Sugars acting as signaling molecules or energy metabolites can influence the progression of leaf senescence. Both sugar starvation and accumulation can promote leaf senescence with diverse mechanisms that are reported in different species. Sugars Will Eventually be Exported Transporters (SWEETs) are proposed to play essential roles in sugar transport, but whether they have roles in senescence and the corresponding mechanism are unclear. Here, we functionally characterized a sugar transporter, OsSWEET1b, which transports sugar and promotes senescence in rice (Oryza sativa L.). OsSWEET1b could import glucose and galactose when heterologously expressed in Xenopus oocytes and translocate glucose and galactose from the extracellular apoplast into the intracellular cytosol in rice. Loss of function of OsSWEET1b decreased glucose and galactose accumulation in leaves. ossweet1b mutants showed accelerated leaf senescence under natural and dark-induced conditions. Exogenous application of glucose and galactose complemented the defect of OsSWEET1b deletion-promoted senescence. Moreover, the senescence-activated transcription factor OsWRKY53, acting as a transcriptional repressor, genetically functions upstream of OsSWEET1b to suppress its expression. OsWRKY53-overexpressing plants had attenuated sugar accumulation, exhibiting a similar phenotype as the ossweet1b mutants. Our findings demonstrate that OsWRKY53 downregulates OsSWEET1b to impair its influx transport activity, leading to compromised sugar accumulation in the cytosol of rice leaves where sugar starvation promotes leaf senescence.

Inhibitory effect of thiol compounds on browning precursors and intermediates in sorbitol/glycine system.

Sorbitol as a sweetener is often thought to be unable to participate in the Maillard reaction causing browning. However, browning of a system was found to be significant when sorbitol was mixed with glycine and heated. The thiol compounds glutathione and cysteine were added to the system, and the inhibition mechanism of the two on the browning of the system was studied by combining the changes of precursor substances, intermediate products and browning degree. When the concentration of thiol compounds reached 25 mg mL-1, both could make the browning inhibition of the system more than 80%, and the accumulated glucose concentration was reduced to <35% of the control. The production of 3-deoxyglucosone, a precursor of melanoidin, was significantly reduced. Glutathione and cysteine directly inhibited the production of substrates in the sorbitol/glycine system, reduced glucose accumulation through competitive consumption and captured highly active intermediates through sulfhydryl groups. This has implications for the browning control of food systems containing sugar alcohols. © 2024 Society of Chemical Industry.

A biomimetic nanocarrier facilitates glucose consumption and reactive oxide species accumulation in enzyme therapy for colorectal cancer

Glucose oxidase (GOx)-based enzyme therapeutics are potential alternatives for colorectal cancer (CRC) treatment via glucose consumption and accumulation of hydrogen peroxide (H2O2). Given that H2O2 can be eliminated by cytoprotective autophagy, autophagy inhibitors that can interrupt autolysosome-induced H2O2 elimination are promising combination drugs of GOx. Here, we developed a multifunctional biomimetic nanocarrier for effective co-delivery of an autophagy inhibitor-chloroquine phosphate (CQP) and GOx to exert their synergistic effect by irreversibly upregulating intracellular reactive oxygen species (ROS) levels. Poly (D, l-lactide-co-glycolide) (PLGA) nanoparticles (NPs) were used to encapsulate both GOx and CQP using a W/O/W multi-emulsion method. Calcium phosphate (CaP) was used to “fix” CQP to GOx in the internal water phase, where it served as a pH-sensitive unit to facilitate intracellular drug release. Folic acid-modified red blood cell membranes (FR) were used to camouflage the GOx/CQP/CaP encapsulated PLGA NPs (referred to as PLGA/GCC@FR). In an AOM/DSS-induced CRC mouse model, PLGA/GCC@FR exhibited improved antitumor effects, in which the number of tumor nodes were only a quarter of that in the free drug combination group. The enhanced therapeutic effects of PLGA/GCC@FR were attributed to the prolonged tumor retention which was verified by both dynamic in vivo imaging and drug biodistribution. This multifunctional biomimetic nanocarrier facilitated combined enzyme therapeutics by depleting glucose and augmenting intracellular ROS levels in tumor cells, which exerted a synergistic inhibitory effect on tumor growth. Therefore, this study proposed a novel strategy for the enhancement of combined enzyme therapeutics, which provided a promising method for effective CRC treatment.

Association of Alu APO Gene Marker with Type 2 Diabetic patients of Dimapur District, Nagaland India

ABSTRACT: With Type 2 Diabetes, the body either produces insufficient insulin or rejects it, which leads to an accumulation of glucose in the blood. Type 2 diabetes affects 90% of the population.. Examining the relationship between Type 2 diabetes patients from the tribal tribes of Dimapur District and the Alu APO gene marker was the main goal of this study. Using the use of random sampling, blood samples were taken from 31 Type 2 Diabetes Mellitus patients at Eden Medical Centre in Dimapur and 31 control samples were collected from healthy individuals . Depending on the patient availability, blood samples were taken from both male and female patients. Within a day of collecting the blood, DNA was extracted. PCR and an allele-specific marker (APO) were used for genotyping. After genotyping, results were recorded by visualizing the PCR products in UV transilluminator. With this investigation, we discovered that the female exhibits a high statistical significance in the DD genotype (0.00*). On the other hand, neither genotype is statistically significant in males.

Association of Alu APO Gene Marker with Type 2 Diabetic patients of Dimapur District, Nagaland India

ABSTRACT: With Type 2 Diabetes, the body either produces insufficient insulin or rejects it, which leads to an accumulation of glucose in the blood. Type 2 diabetes affects 90% of the population.. Examining the relationship between Type 2 diabetes patients from the tribal tribes of Dimapur District and the Alu APO gene marker was the main goal of this study. Using the use of random sampling, blood samples were taken from 31 Type 2 Diabetes Mellitus patients at Eden Medical Centre in Dimapur and 31 control samples were collected from healthy individuals . Depending on the patient availability, blood samples were taken from both male and female patients. Within a day of collecting the blood, DNA was extracted. PCR and an allele-specific marker (APO) were used for genotyping. After genotyping, results were recorded by visualizing the PCR products in UV transilluminator. With this investigation, we discovered that the female exhibits a high statistical significance in the DD genotype (0.00*). On the other hand, neither genotype is statistically significant in males.

Effects of Different Forms and Proportions of Nitrogen on the Growth, Photosynthetic Characteristics, and Carbon and Nitrogen Metabolism in Tomato.

Optimal plant growth in many species is achieved when the two major forms of N are supplied at a particular ratio. This study investigated optimal nitrogen forms and ratios for tomato growth using the 'Jingfan 502' tomato variety. Thirteen treatments were applied with varying proportions of nitrate nitrogen (NN), ammonium nitrogen (AN), and urea nitrogen (UN). Results revealed that the combination of AN and UN inhibited tomato growth and photosynthetic capacity. Conversely, the joint application of NN and UN or NN and AN led to a significant enhancement in tomato plant growth. Notably, the T12 (75%UN:25%NN) and T4 (75%NN:25%AN) treatments significantly increased the gas exchange and chlorophyll fluorescence parameters, thereby promoting the accumulation of photosynthetic products. The contents of fructose, glucose, and sucrose were significantly increased by 121.07%, 206.26%, and 94.64% and by 104.39%, 156.42%, and 61.40%, respectively, compared with those in the control. Additionally, AN favored starch accumulation, while NN and UN favored fructose, sucrose, and glucose accumulation. Gene expression related to nitrogen and sugar metabolism increased significantly in T12 and T4, with T12 showing greater upregulation. Key enzyme activity in metabolism also increased notably. In summary, T12 enhanced tomato growth by upregulating gene expression, increasing enzyme activity, and boosting photosynthesis and sugar accumulation. Growers should consider using NN and UN to reduce AN application in tomato fertilization.

FoxO3a Drives the Metabolic Reprogramming in Tamoxifen-Resistant Breast Cancer Cells Restoring Tamoxifen Sensitivity.

Tamoxifen-resistant breast cancer cells (TamR-BCCs) are characterized by an enhanced metabolic phenotype compared to tamoxifen-sensitive cells. FoxO3a is an important modulator of cell metabolism, and its deregulation has been involved in the acquisition of tamoxifen resistance. Therefore, tetracycline-inducible FoxO3a was overexpressed in TamR-BCCs (TamR/TetOn-AAA), which, together with their control cell line (TamR/TetOn-V), were subjected to seahorse metabolic assays and proteomic analysis. FoxO3a was able to counteract the increased oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) observed in TamR by reducing their energetic activity and glycolytic rate. FoxO3a caused glucose accumulation, very likely by reducing LDH activity and mitigated TamR biosynthetic needs by reducing G6PDH activity and hindering NADPH production via the pentose phosphate pathway (PPP). Proteomic analysis revealed a FoxO3a-dependent marked decrease in the expression of LDH as well as of several enzymes involved in carbohydrate metabolism (e.g., Aldolase A, LDHA and phosphofructokinase) and the analysis of cBioPortal datasets of BC patients evidenced a significant inverse correlation of these proteins and FoxO3a. Interestingly, FoxO3a also increased mitochondrial biogenesis despite reducing mitochondrial functionality by triggering ROS production. Based on these findings, FoxO3a inducing/activating drugs could represent promising tools to be exploited in the management of patients who are refractory to antiestrogen therapy.

Adaptive reactions of wheat plants to drought conditions under the influence of salicylic acid

Background. Drought is one of the most important factors affecting plant growth and productivity. The study addressed the perspectives of usage of salicylic acid, a stress protective compound, to increase the adaptive potential of Triticum aestivum L. plants under drought conditions. The effect of salicylic acid on the photosynthetic apparatus of wheat plants under the conditions of drought with a subsequent gradual resumption of watering was investigated. Materials and methods. Plants of the Podolyanka variety of wheat (Triticum aestivum L.) were the objects of our study. Seeds were pre-soaked in a solution of salicylic acid (50 mM) for 3 h. First seeds germinated in an incubator, and on the 3rd day of growth were transplanted into plastic pots (d = 14 cm). Plants were grown on soil substrate, whose humidity was maintained at 60 % of full moisture capacity – the optimal water supply. The model of drought was created by the simultaneous cessation of irrigation (30 % of soil moisture capacity) for 12 days. Upon termination of the drought, soil moisture in the pots was adjusted to 60 % of its full capacity. The control plants were grown from the seeds not treated with salicylic acid under conditions of optimal water supply (60 %). Study samples were taken from the shoots of wheat on the 7th, 9th and 12th days of the drought period and on the first day after the resumption of irrigation (14 days). The concentrations of TBA-active products, chlorophyll, carotenoids, glucose, sucrose and chlorophyllase activity were determined. Results. The influence of salicylic acid on the content of chlorophyll, carotenoids and TBA-active products along with chlorophyllase activity in shoots of wheat under the drought conditions on the early stages of ontogenesis was determined. It was found that both drought and salicylic acid modify the content of chlorophyll and carotenoids in the shoots of Triticum aestivum L., apparently by altering their metabolism. Chlorophyllase plays an important role in the adaptation of photosynthetic apparatus to the drought conditions. Our results suggest that salicylic acid causes an increase in the content of photosynthetic pigments and a decrease in chlorophyllase activity in drought conditions. In addition, salicylate causes the accumulation of glucose and sucrose in the shoot tissues of wheat plants under stressful conditions. Conclusions. Our research suggests participation of salicylic acid in the plants’ adaptation processes under the conditions of moisture deficiency. It was also found that under the effect of salicylic acid the content of TBA-active products decreases in the plant shoots under the conditions of drought. Considering the fact that the content of TBA-active products is an important indicator of lipid peroxidation intensity, the decrease of this index reveals the reduced activity of free radical processes in plant tissues under the effect of salicylic acid. Thus, it can be assumed that SA has a positive effect on plant metabolism under drought conditions.

Effect of Individual Protective Covers on Young ‘Valencia’ Orange (Citrus sinensis) Tree Physiology

Huanglongbing (HLB), an important citrus disease, causes many physiological and anatomical changes such as phloem dysfunction, imbalance in carbohydrate partitioning, decrease in leaf chlorophyll, and nutritional imbalances in the affected trees, ultimately resulting in tree decline. In Florida, HLB is associated with phloem-limited bacteria Candidatus Liberibacter asiaticus (CLas), and it is vectored by the Asian citrus psyllid (Diaphorina citri). No cure for HLB has been found, and most of the HLB management efforts have been focused on vector control or exclusion, improved nutrient management, and the use of HLB-tolerant rootstocks. Individual protective covers (IPCs) are a type of psyllid exclusion tool that is increasingly used by growers for HLB management of newly planted citrus trees. However, no studies have evaluated their influence on citrus tree physiology. This study investigated the effect of IPCs and different rates of insecticides on CLas infection and different physiological attributes, including soluble (glucose, fructose, and sucrose) and nonsoluble (starch) carbohydrates, leaf chlorophyll, and leaf macronutrients and micronutrients over 2.5 years of field growth. The treatments (tree cover and insecticides rate) were applied in newly planted ‘Valencia’ sweet orange (Citrus sinensis) trees grafted on ‘Cleopatra’ (C. reticulata) rootstock. The IPCs prevented CLas transmission and accumulation of foliar starch, sucrose, and glucose commonly associated with HLB. IPC-covered trees had more leaf chlorophyll-a and chlorophyll-b than noncovered trees and more leaf nitrogen (N) and zinc (Zn). Our findings suggest that IPCs effectively prevent CLas infection and maintain the physiological health of young citrus trees under heavy HLB pressure. Therefore, IPCs are recommended as an important component of integrated pest management for this devastating disease.

Circ_0005015 upregulates BACH1 to promote aggressive behaviors in glioblastoma by sponging microRNA-382-5p.

To investigate the potential role and molecular mechanism of circ_0005015 in GBM progression. Circ_0005015, microRNA-382-5p (miR-382-5p), and BTB domain and CNC homolog 1 (BACH1) levels were measured by real-time quantitative polymerase chain reaction (RT-qPCR). Cell proliferation was determined by MTT, colony formation, and EdU assays. Cell apoptosis was analyzed using flow cytometry. Cell migration and invasion were assessed using wound healing and transwell assays. Glucose accumulation and lactate levels were examined by the corresponding kit. RNA pull-down and dual-luciferase reporter assays were performed to confirm the interaction between miR-382-5p and circ_0005015 or BACH1. Protein levels of MMP9, PCNA, and BACH1 were examined using western blot assay. Role of circ_0005015 on tumor growth in vivo was analyzed using a xenograft tumor model. Circ_0005015 content was up-regulated in GBM patients and cells, its knockdown restrained GBM cell proliferation, migration, invasion, glycolysis, and triggered apoptosis. Mechanistically, we found that circ_0005015 could directly interact with miR-382-5p and serve as a miRNA sponge to regulate BACH1 expression. In addition, circ_0005015 knockdown might repress tumor growth in vivo. Circ_0005015 boosted GBM progression via binding to miR-382-5p to up-regulate BACH1, which may offer new effective targets for GBM treatment.

Knockout of the sugar transporter OsSTP15 enhances grain yield by improving tiller number due to increased sugar content in the shoot base of rice (Oryza sativa L.).

Sugar transporter proteins (STPs) play critical roles in regulating plant stress tolerance, growth, and development. However, the role of STPs in regulating crop yield is poorly understood. This study elucidates the mechanism by which knockout of the sugar transporter OsSTP15 enhances grain yield via increasing the tiller number in rice. We found that OsSTP15 is specifically expressed in the shoot base and vascular bundle sheath of seedlings and encodes a plasma membrane-localized high-affinity glucose efflux transporter. OsSTP15 knockout enhanced sucrose and trehalose-6-phosphate (Tre6P) synthesis in leaves and improved sucrose transport to the shoot base by inducing the expression of sucrose transporters. Higher glucose, sucrose, and Tre6P contents were observed at the shoot base of stp15 plants. Transcriptome and metabolome analyses of the shoot base demonstrated that OsSTP15 knockout upregulated the expression of cytokinin (CK) synthesis- and signaling pathway-related genes and increased CK levels. These findings suggest that OsSTP15 knockout represses glucose export from the cytoplasm and simultaneously enhances sugar transport from source leaves to the shoot base by promoting the synthesis of sucrose and Tre6P in leaves. Subsequent accumulation of glucose, sucrose, and Tre6P in the shoot base promotes tillering by stimulating the CK signaling pathway.

Second-generation antipsychotics and metabolic syndrome: a role for mitochondria

Psychosis is a known risk factor for developing metabolic syndrome (MetS). The risk is even greater in patients who are taking second-generation antipsychotics (SGAs). SGAs exacerbate metabolic abnormalities and lead to a 3-fold increased risk of severe weight gain, type 2 diabetes, and cardiovascular disease in patients. Mitochondrial dysfunction is a hallmark of MetS. Mitochondria process glucose and fatty acids into ATP. If these processes are impaired, it can result in dyslipidaemia, hyperglycaemia and an imbalance between nutrient input and energy output. This leads to increased adiposity, insulin resistance and atherosclerosis. It is unclear how SGAs induce MetS and how mitochondria might be involved in this process. It has been found that SGAs impair cellular glucose uptake in liver, dysregulating glucose and fatty acid metabolism which leads to an accumulation of glucose and/or lipids and an increase reactive oxygen species (ROS) which target mitochondrial proteins. This affects complexes of the electron transport chain (ETC) to reduce mitochondrial respiration. While there is a suggestion that SGAs may interact with a variety of processes that disrupt mitochondrial function, some of the results are conflicting, and a clear picture of how SGAs interact with mitochondria in different cell types has not yet emerged. Here, we outline the current evidence showing how SGAs may trigger mitochondrial dysfunction and lead to the development of MetS.

Plant Life with and without Oxygen: A Metabolomics Approach.

Oxygen deficiency is an environmental challenge which affects plant growth, the development and distribution in land and aquatic ecosystems, as well as crop yield losses worldwide. The capacity to exist in the conditions of deficiency or the complete lack of oxygen depends on a number of anatomic, developmental and molecular adaptations. The lack of molecular oxygen leads to an inhibition of aerobic respiration, which causes energy starvation and the acceleration of glycolysis passing into fermentations. We focus on systemic metabolic alterations revealed with the different approaches of metabolomics. Oxygen deprivation stimulates the accumulation of glucose, pyruvate and lactate, indicating the acceleration of the sugar metabolism, glycolysis and lactic fermentation, respectively. Among the Krebs-cycle metabolites, only the succinate level increases. Amino acids related to glycolysis, including the phosphoglycerate family (Ser and Gly), shikimate family (Phe, Tyr and Trp) and pyruvate family (Ala, Leu and Val), are greatly elevated. Members of the Asp family (Asn, Lys, Met, Thr and Ile), as well as the Glu family (Glu, Pro, Arg and GABA), accumulate as well. These metabolites are important members of the metabolic signature of oxygen deficiency in plants, linking glycolysis with an altered Krebs cycle and allowing alternative pathways of NAD(P)H reoxidation to avoid the excessive accumulation of toxic fermentation products (lactate, acetaldehyde, ethanol). Reoxygenation induces the downregulation of the levels of major anaerobically induced metabolites, including lactate, succinate and amino acids, especially members of the pyruvate family (Ala, Leu and Val), Tyr and Glu family (GABA and Glu) and Asp family (Asn, Met, Thr and Ile). The metabolic profiles during native and environmental hypoxia are rather similar, consisting in the accumulation of fermentation products, succinate, fumarate and amino acids, particularly Ala, Gly and GABA. The most intriguing fact is that metabolic alterations during oxidative stress are very much similar, with plant response to oxygen deprivation but not to reoxygenation.

Integrating network analysis and experimental validation to reveal the mechanism of pinocembrin in alleviating high glucose and free fatty acid-induced lipid accumulation in HepG2 cells

Hepatocyte lipid accumulation in type 2 diabetes mellitus (T2DM) promotes the development of metabolic dysfunction-associated steatosis liver disease (MASLD), whereas no specific drug treatment is available. Pinocembrin assists in the treatment of many diseases, however, little is known about its protective effect on hepatic lipid metabolism disorders induced by T2DM. In this study, the ameliorative effects of pinocembrin on T2DM-induced hepatocyte lipid accumulation were investigated by in vitro experiments combined with a comprehensive analysis strategy of network pharmacology and molecular docking. High glucose and free fatty acid co-cultured HepG2 cell line was used. The results indicated that pinocembrin reduced lipid deposition by modulating the release of Cyclooxygenase-2 (COX-2)-mediated inflammatory factors and improving insulin resistance (IR) in HepG2 cells. Overall, the findings of this study suggested that pinocembrin ameliorated lipid accumulation and IR in vitro, and thus may be a potential therapeutic agent for the treatment of T2DM-induced hepatic steatosis.

Substrate and fertigation management modulate microgreens production, quality and resource efficiency

Long-term space missions will require a self-sustaining food production system to meet the crew’s nutritional and health needs. For this purpose, plant-based food production systems with elevated resource efficiency are required, based on advanced agricultural technologies that produce phytonutrient-rich crops. In addition to the resource requirements for crop production on Earth, volume and time efficiency become essential factors to consider for food production in space. Microgreens represent a promising candidate for space farming as they have a high harvest index, short cultivation cycle, and high nutritional potential. However, the development of specific technical protocols for growing microgreens in space is essential since different agronomic inputs, such as substrates and fertigation, can modulate productivity, quality and resource efficiency of microgreens cultivation. The current work examines the effects of different substrates (coconut fiber and cellulose sponge) and nutrient solution (NS) management strategies (quarter strength Hoagland and half strength Hoagland/osmotic water) on the production of two species of microgreens [Raphanus sativus cv. Saxa 2 (Radish); Brassica oleracea var. capitata f. sabauda cv. Vertus (Savoy cabbage)]. The appraisal focused on (i) biomass production and quality, and (ii) sizing of space facilities devoted to the production of phytonutrients required for the astronauts’ wellbeing. In our study, the interaction among species, substrate and NS significantly affected the accumulation of fructose, sucrose, total soluble non-structural carbohydrates and nitrate as well as the daily production of total ascorbic acid and, in turn, the required microgreens serving to supply its adequate daily intake. Species-substrate interaction effects on fresh yield, dry yield, dry matter, anthocyanins, TPC, β-carotene and sulfate content as well as the cultivation surface required to produce the adequate daily intake of ascorbic acid (AscA) were assessed. Substrate-NS interaction modulated the anthocyanins, violaxanthin and sulfate contents independently of species. On the other hand, single factor effects were identified with respect to the accumulation of lutein, chlorophylls, glucose, and starch. Therefore, the management of microgreens cultivation in terms of NS and substrate is an effective tool to meet the phytochemical requirements of the crew.

Identifying Donors for Anaerobic Germination Tolerance and Direct Seeded Rice Cultivation by Exploring Seed and Seedling Traits

Background: Anaerobic conditions in waterlogged soil affect germination rate significantly reducing rice yields. Under wet direct seeded condition, only limited availability of rice genotypes are suitable for anaerobic germination. So, there is an urgent need to identify rice genotypes for enhanced germination even under anoxic stress. Methods: Experiment was conducted in glass house, Department of Crop Physiology, Tamil Nadu Agricultural University, Coimbatore. In this study, 22 rice germplams with three replications were evaluated for seed and seedling traits underlying anaerobic germination tolerance. Main aim of this study is to explore the starch and sugar relation under anoxic stress and identifying tolerant genotypes for direct seeded rice cultivation. Result: Tolerant genotypes had early emergences, higher shoot and root length along with higher starch degradation and sugar accumulation under waterlogged condition. Cluster analysis revealed that Karuppukavuni, Kalanamak, CBMAS 14065 and Kodavilayan were identified as tolerant genotypes and suitable for wet direct seeded rice cultivation. Finally higher starch degradation coupled with higher accumulation of glucose and fructose were the key traits underlying anaerobic germination tolerance in tolerant genoytpes. Shoot length, root length and sucrose contents had higher genotypic coefficient of variance, phenotypic coefficient of variance coupled with high heritability indicating scope for enhancing anaerobic germination tolerance.

CsABF3-activated CsSUT1 pathway is implicated in pre-harvest water deficit inducing sucrose accumulation in citrus fruit

Pre-harvest water deficit (PHWD) plays an important role in sugar accumulation of citrus fruit. However, the mechanism is not known well. Here, it was confirmed that PHWD promoted sucrose accumulation of citrus fruit, but had limited effect on fructose, glucose and total acid. A sucrose transporter, CsSUT1, which localizes to the plasma membrane, was demonstrated to function in sucrose transport induced by PHWD. Compared to wild-type, CsSUT1 overexpression in citrus calli stimulated sucrose, fructose and glucose accumulation, while its silencing in juice sacs reduced sucrose accumulation. Increased sugar accumulation in transgenic lines enhanced plant drought tolerance, and resulted in decreased electrolyte leakage, malondialdehyde and hydrogen peroxide contents, as well as increased superoxide dismutase activity and proline contents. An abscisic acid (ABA)-responsive transcription factor, CsABF3, was found with a same expression pattern with CsSUT1 under PHWD. Yeast one-hybrid, electrophoretic mobility shift assay and dual-luciferase assays all revealed that CsABF3 directly bound with the CsSUT1 promoter by ABA responsive elements. When CsABF3 was overexpressed in citrus calli, the sucrose, fructose and glucose concentration increased correspondingly. Further, transgenic studies demonstrated that CsABF3 could affect sucrose accumulation by regulating CsSUT1. Overall, this study revealed a regulation of CsABF3 promoting CsSUT1 expression and sucrose accumulation in response to PHWD. Our results provide a detail insight into the quality formation of citrus fruit.

The cell functions of phospholipase C-1, Ca2+/H+ exchanger-1, and secretory phospholipase A2 in tolerance to stress conditions and cellulose degradation in Neurospora crassa.

We investigated the cell functions of the Ca2+ signaling genes phospholipase C-1 (plc-1), Ca2+/H+ exchanger (cpe-1), and secretory phospholipase A2 (splA2) for stress responses and cellulose utilization in Neurospora crassa. The Δplc-1, Δcpe-1, and ΔsplA2 mutants displayed increased sensitivity to the alkaline pH and reduced survival during induced thermotolerance. The ΔsplA2 mutant also exhibited hypersensitivity to the DTT-induced endoplasmic reticulum (ER) stress, increased microcrystalline cellulose utilization, increased protein secretion, and glucose accumulation in the culture supernatants. Moreover, the ΔsplA2 mutant could notgrow on microcrystalline cellulose during ER stress. Furthermore, plc-1, cpe-1, and splA2 synthetically regulate the acquisition of thermotolerance induced by heat shock, responses to alkaline pH and ER stress, and utilization of cellulose and other alternate carbon sources in N. crassa. In addition, expression of the alkaline pH regulator, pac-3, and heat shock proteins, hsp60, and hsp80 was reduced in the Δplc-1, Δcpe-1, and ΔsplA2 single and double mutants. The expression of the unfolded protein response (UPR) markers grp-78 and pdi-1 was also significantly reduced in the mutants showing growth defect during ER stress. The increased cellulolytic activities of the ΔsplA2 and Δcpe-1; ΔsplA2 mutants were due to increased cbh-1, cbh-2, and endo-2 expressionin N. crassa. Therefore, plc-1, cpe-1, and splA2 are involved in stress responses and cellulose utilizationin N. crassa.

Transcriptomic-metabolomic analysis of magnesium-stimulated in peel coloration of Satsuma mandarin

Magnesium (Mg) has been found to promote the color change citrus peel, but the underlying mechanism remains unclear. In this study, Mg application treatment significantly increased the Mg content in the peel of Satsuma mandarin fruit during the expansion stage (90–150 days after flowering). Mg fertilizer treatment was also found to significantly reduce chlorophyll (Chl) a content and increase β, β-xanthophyll (β-cryptoxanthin, zeaxanthin, neoxanthin), and abscisic acid (ABA) content in the flavedo during the key period of color change in Satsuma mandarin (165–195 days after flowering). Under Mg fertilizer treatment, Chl biosynthesis genes (CitGGDR, CitCHLH, CitCHLM, CitCHL27, and CitPORA) was down-regulated and that of Chl degradation genes (CitNYC, CitPPH, CitPAO, and CitRCCR) was up-regulated, which resulted in a lower Chl content in the flavedo than the control. Moreover, Mg fertilizer treatment up-regulated carotenoid biosynthesis genes (CitPSY, CitPDS, CitZDS, CitLCYb1, CitLCYb2, CitZEP, CitNCED2, and CitNCED3), leading to the accumulation of β, β-xanthophyll and ABA in the flavedo. Mg fertilizer treatment also promoted sugar (mainly fructose, glucose, and sucrose) accumulation in fruit flavedo, which showed significant negative correlations with Chl, α-carotene, lutein, and β-carotene, but positive correlations with β, β-xanthophyll compositions, and ABA in the flavedo. An analysis integrating transcriptome and metabolome data revealed that Mg may promote the color change of Satsuma mandarin fruit flavedo by regulating various metabolic pathways related to peel coloration, such as sugar accumulation, Chl degradation, carotenoid and ABA biosynthesis, and carbon fixation. The results can explain the regulatory pathways and networks of Mg-induced citrus peel coloration.