Tag-free fluorometric aptasensor for detection of chromium(VI) in foods via SYBR Green I signal amplification and aptamer structure transition.

BACKGROUND: In response to growing concerns regarding heavy metal contamination in food, particularly chromium (Cr)(VI) contamination, this study presented a simple, sensitive and practical method for Cr(VI) detection. RESULTS: A magnetic separation-based capture-exponential enrichment ligand system evolution (SELEX) method was used to identify and characterize DNA aptamers with a high affinity for Cr(VI). An aptamer, Cr-15, with a dissociation constant (Kd) of 4.42 ± 0.44 µmol L-1 was obtained after only eight rounds of selection. Further innovative methods combining molecular docking, dynamic simulation and thermodynamic analysis revealed that CrO4 2- could bind to the 19th and 20th guanine bases of Cr-15 via hydrogen bonds. Crucially, a label-free fluorometric aptasensor based on SYBR Green I was successfully constructed to detect CrO4 2-, achieving a linear detection range of 60-300 nmol L-1 with a lower limit of detection of 44.31 nmol L-1. Additionally, this aptasensor was able to quantitatively detect CrO4 2- in grapes and broccoli within 40 min, with spike recovery rates ranging from 89.22% to 108.05%. The designed fluorometric aptasensor exhibited high selectivity and could detect CrO4 2- in real samples without sample processing or target pre-enrichment. CONCLUSION: The aptasensor demonstrated its potential as a reliable tool for monitoring Cr(VI) contamination in fruit and vegetable products. © 2024 Society of Chemical Industry.

Phenotype and signaling pathway analysis to explore the interaction between tomato plants and TYLCV in different organs.

Tomato yellow leaf curl disease (TYLCD), caused by Tomato yellow leaf curl virus (TYLCV), is one of the most destructive diseases in tomato cultivation. By comparing the phenotypic characteristics and virus quantities in the susceptible variety 'Cooperation 909 Red Tomatoes' and the resistant variety 'Huamei 204' after inoculation with TYLCV infectious clones, our study discovered that the root, stem and leaf growth of the susceptible variety 'Cooperation 909 Red Tomatoes' were severely hindered and the resistant variety 'Huamei 204' showed growth inhibition only in roots. TYLCV accumulation in roots were significantly higher than in leaves. Further, we examined the expression of key genes in the SA and JA signalling pathways in leaves, stems and roots and found the up-regulation of SA-signalling genes in all organs of the susceptible variety after inoculation with TYLCV clones. Interestingly, SlJAZ2 in roots of the resistant variety was significantly down-regulated upon TYLCV infection. Further, we silenced the SlNPR1 and SlCOI1 genes individually using virus induced gene silencing system in tomato plants. We found that viruses accumulated to a higher level in SlNPR1 silenced plants than wild type plants, and the virus quantity in roots was significantly increased in SlCOI1 silenced plants. These results provide new insights for advancing research in understanding tomato-TYLCV interaction.

Advances in colorimetric aptasensors for heavy metal ion detection utilizing nanomaterials: a comprehensive review.

Heavy metal ion contamination poses significant environmental and health risks, necessitating rapid and efficient detection methods. In the last decade, colorimetric aptasensors have emerged as powerful tools for heavy metal ion detection, owing to their notable attributes such as high specificity, facile synthesis, adaptability to modifications, long-term stability, and heightened sensitivity. This comprehensive overview summarizes the key developments in this field over the past ten years. It discusses the principles, design strategies, and innovative techniques employed in colorimetric aptasensors using nanomaterials. Recent advancements in enhancing sensitivity, selectivity, and on-site applicability are highlighted. The review also presents application studies of successful heavy metal ion detection using colorimetric aptasensors, underlining their potential for environmental monitoring and health protection. Finally, future directions and challenges in the continued evolution of these aptasensors are outlined.

Improving aptamer performance: key factors and strategies.

Aptamers are functional single-stranded oligonucleotide fragments isolated from randomized libraries by Systematic Evolution of Ligands by Exponential Enrichment (SELEX), exhibiting excellent affinity and specificity toward targets. Compared with traditional antibody reagents, aptamers display many desirable properties, such as low variation and high flexibility, and they are suitable for artificial and large-scale synthesis. These advantages make aptamers have a broad application potential ranging from biosensors, bioimaging to therapeutics and other areas of application. However, the overall performance of aptamer pre-selected by SELEX screening is far from being satisfactory. To improve aptamer performance and applicability, various post-SELEX optimization methods have been developed in the last decade. In this review, we first discuss the key factors that influence the performance or properties of aptamers, and then we summarize the key strategies of post-SELEX optimization which have been successfully used to improve aptamer performance, such as truncation, extension, mutagenesis and modification, splitting, and multivalent integration. This review shall provide a comprehensive summary and discussion of post-SELEX optimization methods developed in recent years. Moreover, by discussing the mechanism of each approach, we highlight the importance of choosing the proper method to perform post-SELEX optimization.

Physiological and transcriptome profiling revealed defense networks during Cladosporium fulvum and tomato interaction at the early stage.

Tomato leaf mold caused by Cladosporium fulvum (C. fulvum) is a serious fungal disease which results in huge yield losses in tomato cultivation worldwide. In our study, we discovered that ROS (reactive oxygen species) burst was triggered by C. fulvum treatment in tomato leaves. RNA-sequencing was used to identify differentially expressed genes (DEGs) induced by C. fulvum inoculation at the early stage of invasion in susceptible tomato plants. Gene ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases were used to annotate functions of DEGs in tomato plants. Based on our comparative analysis, DEGs related to plant-pathogen interaction pathway, plant hormone signal transduction pathway and the plant phenylpropanoid pathway were further analyzed. Our results discovered that a number of core defense genes against fungal invasion were induced and plant hormone signal transduction pathways were impacted by C. fulvum inoculation. Further, our results showed that SA (salicylic acid) and ABA (abscisic acid) contents were accumulated while JA (jasmonic acid) content decreased after C. fulvum inoculation in comparison with control, and quantitative real-time PCR to detect the relative expression of genes involved in SA, ABA and JA signaling pathway further confirmed our results. Together, results will contribute to understanding the mechanisms of C. fulvum and tomato interaction in future.

Structural characterization of a polysaccharide from Abelmoschus esculentus L. Moench (okra) and its hypoglycemic effect and mechanism on type 2 diabetes mellitus.

A novel acidic polysaccharide named AeP-P-1 was prepared from Abelmoschus esculentus L. Moench (okra). AeP-P-1 is a heteropolysaccharide with a molecular weight of 3.02 × 103 kDa and is composed of L-rhamnose, D-galactose, and D-galacturonic acid in the ratio 1.87 : 3.58 : 1.00. Structural characterization based on methylation and 1D/2D NMR analyses indicated that AeP-P-1 is composed of T-linked-Rhap, T-linked-Galp, 1,2,4-linked-Rhap, 1,4-linked-Galp, 1,6-linked-Galp, and 1,3,4-linked-Galp in a molar ratio of 2.42 : 3.36 : 6.46 : 13.31 : 3.12 : 1, respectively. The hypoglycemic effect and mechanism of AeP-P-1 on type 2 diabetes mellitus were also explored. Firstly, AeP-P-1 can reduce blood lipids and liver and kidney damage caused by T2DM. Finally, AeP-P-1 induces the phosphorylation of GSK3ß, maintains the activity of glycogen synthase (GCS), and promotes glycogen synthesis by regulating the expression of insulin/PI3K/Akt pathway proteins. These results indicated that AeP-P-1 could be developed as a potential ingredient in immunostimulatory agents.

First Report of Enterobacter cloacae Causing Stem, Leaf and Fruit Rot on Tomato in China.

Tomato (Solanum lycopersicum L.), as one of the most economically important and highly nutritious vegetable crops across the world, is widely cultivated in China, one of the largest tomato-concuming countries in the world (Ye et al., 2020; Wang and Liu, 2021). At present, major bacterial diseases in tomato include bacterial speck disease, tomato bacterial wilt and bacterial canker, all of which affect the tomato production around the world (Rosli et al., 2021; Peritore-Galve et al., 2021; Wang et al., 2022). In April 2022, a new bacterial disease was discovered on leaves, stems and fruits of tomato in a farmer's greenhouse located in Longfeng District in DaQing (125°07`-125°15`E, 46°28`-46°32`N), Heilongjiang Province, China. This field had tomato disease incidences approximately 50%. Apparent brown discolorations were found on fruits, leaves and stems in tomato plants. Symptoms were similar to fungal brown spots caused by Phytophthora infestans of tomato (Zhi et al.,2021; Liu et al.,2021) (Supplementary Figure S1). To isolate and identify the pathogen, the tissues of infected fruits, leaves and stems with typical symptoms were excised from diseased plants separately, and were disinfected with 75% ethanol for 10 s followed by 2% NaClO for 3 min and then washed five to eight times with sterile water (Wang et al., 2017). Afterwards, the samples were plated on nutrient agar (NA) solid medium and incubated. After incubation at 30°C for 2-3 days, bacterial colonies were isolated, then purified on nutrient agar (NA) solid medium at least twice by a streak plate method (Dou et al., 2019; Li et al, 2021; Zhao et al., 2022). White colonies grew on the NA medium after incubating for 2 days, showing round, opaque and smooth, which was similar to characteristics described as Enterobacter cloacae (García-González et al., 2018; Li et al, 2021). To further confirm the speculation on the identity of the isolated bacterium, the fragments of 16S rRNA were amplified and sequenced. The sequence of 16S rRNA was uploaded into GeneBank with accession numbers (OP077195.1). BLAST analysis of the sequence showed 97.68% identity with one corresponding sequence of E. cloacae in GeneBank (namely MK937637.1). Furthermore, a phylogenetic tree based on the sequence of 16S rRNA gene revealed that the isolate was grouped in the same clade as E. cloacae (Supplementary Figure S2). Based on Koch postulates to test pathogenicity of isolated bacteria, bacteria were inoculated on 30 day-old healthy tomato plants with three leaves stages, and the re-isolation of bacteria were carried out after 2 days of inoculation. To confirm pathogenicity, the isolates were cultured on LB medium at 30℃ for 2 days to prepare suspensions and adjusted to an optical density (OD) of 0.2 at A600, with a final concentration of 1ⅹ108 CFU/ml. Eight potted tomato plants were sprayed with bacteria suspensions, and eight control potted plants were sprayed with sterile distilled water. These seedlings were incubated in a chamber at 30°C with a 12 h light/dark photoperiod, with 85% relative humidity. After 2 days, inoculated tomato seedlings showed irregular small spots in leaves and brown necrosis at blade tips, and 8 to 10 days later, the leaves of tomato plants browned and died. The symptoms were the same with those of the initial diseased leaves of tomato plants (Supplementary Figure S1). No symptoms were observed on the control leaves (Supplementary Figure S3). Pathogenicity tests were repeated three biological times with same results. Meanwhile, the bacteria strains were re-isolated from symptomatic inoculated seedlings and confirmed as E. cloacae by culture and sequence methods as above. In China, there are no detailed records about the causal agent of this disease on tomato in a published paper in Chinese and English. To our knowledge, this is the first report of Enterobacter leaf brown necrosis caused by E. cloacae on tomato in China. Those results are of great significance for the production and management of tomato in greenhouse and control of the disease.

Physiological and transcriptomic analyses revealed gene networks involved in heightened resistance against tomato yellow leaf curl virus infection in salicylic acid and jasmonic acid treated tomato plants.

Tomato yellow leaf curl virus (TYLCV), a member of the genus Begomovirus of the Geminiviridae family, causes leaf curl disease of tomato that significantly affects tomato production worldwide. SA (salicylic acid), JA (jasmonic acid) or the JA mimetic, COR (coronatine) applied exogenously resulted in improved tomato resistance against TYLCV infection. When compared to mock treated tomato leaves, pretreatment with the three compounds followed by TYCLV stem infiltration also caused a greater accumulation of H2O2. We employed RNA-Seq (RNA sequencing) to identify DEGs (differentially expressed genes) induced by SA, JA, COR pre-treatments after Agro-inoculation of TYLCV in tomato. To obtain functional information on these DEGs, we annotated genes using gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) databases. Based on our comparative analysis, differentially expressed genes related to cell wall metabolism, hormone signaling and secondary metabolism pathways were analyzed in compound treated samples. We also found that TYLCV levels were affected in SlNPR1 and SlCOI1 silenced plants. Interestingly, compared to the mock treated samples, SA signaling was hyper-activated in SlCOI1 silenced plants which resulted in a significant reduction in viral titer, whereas in SINPR1 silencing tomato plants, there was a 19-fold increase in viral load. Our results indicated that SA, JA, and COR had multiple impacts on defense modulation at the early stage of TYLCV infection. These results will help us better understand SA and JA induced defenses against viral invasion and provide a theoretical basis for breeding viral resistance into commercial tomato accessions.

CRISRP/Cas9-Mediated Targeted Mutagenesis of Tomato Polygalacturonase Gene (SlPG) Delays Fruit Softening.

Polygalacturonase (PG) gene has been documented as a key candidate for the improvement of fruit firmness, which is a target trait for tomato production because it facilitates transportation and storage. To reduce the expression of the PG gene, most of the elite commercial tomato varieties were obtained by RNA interference technology. However, this approach of producing commercialized tomatoes by integration of the exogenous gene is controversial. In this work, CRISPR/Cas9 technology was used to induce the targeted mutagenesis of the SlPG gene to delay the softening of tomato fruit. Results showed that the SlPG gene was frameshift mutated by 4 bp deletion, 10 bp deletion, and 1 bp insertion, which generated premature translation termination codons. Compared with wild-type (WT), homozygous T1-generation tomato plants exhibited late fruit softening under natural conditions. Consistent with this phenomenon, the firmness value of WT fruit was lower in slpg mutant fruit, and the physiological loss of water was higher. Collectively, these data demonstrate that the mutation of the SlPG gene delays tomato fruit softening. More importantly, 8 out of 20 transgene-free tomato plants, which were homozygous for null alleles of SlPG, were separated in the T3-generation of line slpgT2-#2. This transgene-free slpg may provide materials for more in-depth research of SlPG functions and the molecular mechanism of fruit softening in tomatoes.

Rheological properties of polysaccharides from Pholiota nameko with different temperature extraction: Concentration, pH, temperature, and saltion.

Cold and hot water extracted polysaccharides (CW-PNPs and HW-PNPs) were isolated from Pholiota nameko. The rheological properties of PNPs were investigated by steady shear and oscillatory rheological measurements. The PNPs exhibited typical non-Newtonian and shear-thinning behavior, which are affected by PNP concentration, temperature, pH value, salt ion, and concentration. Specifically, the apparent viscosity of the two PNPs solutions at concentration of 1% (w/w) was shown as HW-PNPs > CW-PNPs. The apparent viscosity of PNPs decreases under acidic and alkaline conditions and when the temperature rises; K+ and Na+ cause the apparent viscosity of CW-PNPs to decrease, while Ca2+ and Al3+ are opposite. The addition of four different salt ions all caused the apparent viscosity of the HW-PNPs to decrease. The results of dynamic rheological experiments show that G' and G″ showed slightly frequency dependency with G' exceeding G″ throughout the accessible range of frequency for CW-PNPs and HW-PNPs.

Selection and identification of a DNA aptamer for fluorescent detection of netilmicin.

Netilmicin (NET) is an antibiotic widely used in healthcare and agriculture, but it can accumulate in the environment to threat human health. Netilmicin (NET) is an antibiotic used for veterinary purposes, for human therapy and for agricultural purposes. Therefore, there is a need to develop high-sensitive measuring methods to detect NET. Aptamer-based detecting methods are highly sensitive, inexpensive, and portable. In this study, we developed an aptamer-based fluorescence method to detect and quantify NET. NET was first conjugated to magnetic beads by amidation reaction and then NET-coated beads were used as the stationary phase to isolate aptamers by systematic evolution of ligands by exponential enrichment (SELEX) screening method. After ten rounds of SELEX screening, 32 aptamers with NET-binding affinity were obtained and the candidate aptamer APT-21 was finally chosen by comprehensively comparing their secondary structure characters and NET-binding affinity. APT-21 bound to NET with high affinity (Kd = 194.1 nmol/L) and high specificity that it displayed low cross-binding activities on 7 different structural analogs. We also developed a fluorometric assay using SYBR Green I (SG-I) and the APT-21. Key experimental parameters were optimized, including buffer system, SG-I and APT-21 reaction time, SG-I concentration, and aptamer concentration, to improve the detecting sensitivity. Our results suggest that the low limit of detection (LOD) of this method reached a low level of 1.95 nM and it also exhibited a good linear range up to 200 nM. Moreover, we successfully applied our method to detect the NET spiked in tap water and river water with good recoveries in the range from 97% to 111%. In conclusion, our current study isolated a NET-specific aptamer and developed an aptamer-based quantification method, which is promising to apply to detect NET in environmental samples.

Oxytetracycline and Streptomycin Resistance Genes in Xanthomonas arboricola pv. pruni, the Causal Agent of Bacterial Spot in Peach.

Xanthomonas arboricola pv. pruni (Xap) causes bacterial spot, a major worldwide disease of Prunus species. Very few chemical management options are available for this disease and frequent applications of oxytetracycline (OTC) in the United States peach orchards have raised concerns about resistance development. During 2017-2020, 430 Xap strains were collected from ten peach orchards in South Carolina. Seven OTC-resistant (OTC R ) Xap strains were found in 2017 and 2020 from four orchards about 20-270 km apart. Interestingly, the seven strains were also resistant to streptomycin (STR). Six strains grew on media amended with ≤100 µg/mL OTC, while one strain, R1, grew on ≤250 µg/mL OTC. Genome sequence analysis of four representative OTC R strains revealed a 14-20 kb plasmid carrying tetC, tetR, and strAB in each strain. These three genes were transferable to Xanthomonas perforans via conjugation, and they were PCR confirmed in all seven OTC R Xap strains. When tetC and tetR were cloned and expressed together in a sensitive strain, the transconjugants showed resistance to ≤100 µg/mL OTC. When tetC was cloned and expressed alone in a sensitive strain, the transconjugants showed resistance to ≤250 µg/mL OTC. TetC and tetR expression was inducible by OTC in all six wild-type strains resistant to ≤100 µg/mL OTC. However, in the R1 strain resistant to ≤250 µg/mL OTC, tetR was not expressed, possibly due to the presence of Tn3 in the tetR gene, and in this case tetC was constitutively expressed. These data suggest that tetC confers OTC resistance in Xap strains, and tetR regulates the level of OTC resistance conferred by tetC. To our knowledge, this is the first report of OTC resistance in plant pathogenic xanthomonads.

Structural characterization and prebiotic potential of an acidic polysaccharide from Imperial Chrysanthemum.

A novel water-soluble polysaccharide, named ICP-1, was isolated and purified by Sephadex G-200 after extracting the crude polysaccharide (ICP) from Imperial Chrysanthemum. The structural characterization of ICP-1 was determined by physical and chemical methods, FT-IR, NMR, SEM, HPGPC, periodate oxidation, Smith degradation, methylation and Congo red test. Then, acid production and proliferation of lactic acid bacteria and the tolerance tests of simulated gastrointestinal fluid were measured to investigate the activity of prebiotic potential. The results showed that ICP-1 was an acidic hetero-polysaccharide with an average molecular weight of 2.98 × 103 kDa and a specific optical rotation of +155°. The glycosyl residues of ICP-1 were composed of (1→), (1→4) and (1→6) glucose, (1→5) arabinose, (1→4) galacturonic acid and (1→3,6) mannose. Besides, ICP-1 can speed up the acid production of lactic acid bacteria and promote the growth and proliferation of lactic acid bacteria effectively.

Structure, antioxidant property and protection on PC12 of a polysaccharide isolated and screened from Abelmoschus esculentus L.Moench (okra).

AeP-P-2, a pectic polysaccharide, was extracted from the fruit pod of okra. It composed of rhamnose (Rha), arabinose (Ara), glucose (Glc), galactose (Gal) and galacturonic acid (GalA) with the ratio of 4.75:2.01:1.00:4.91:7.24. The main structural feature of AeP-P-2 are 1,4-linked galacturonan units (homogalacturonan backbone) and (1 → 2) and (1 → 2,4) linked Rha (rhamnogalacturonan I region). And the other side chains contained →1)-linked Ara, (1 → 5)-linked Ara, (1 → 4)-linked Glc, (1 → 6)-linked Gal, (1 → 4)-linked Rha, (1 → 2,4)-linked Rha, →1)-linked Ara and →1)-linked Gal. When the concentration of AeP-P-2 was 3.2 mg/mL, the scavenging rates on DPPH·, ABTS, O2-· and ·OH reached to 61.88%, 87.10%, 52.17% and 60.32%, respectively. AeP-P-2 also could protect PC12 cells from the damage of H2O2 and reduce apoptosis caused by oxidative damage by decreasing the level of ROS. The findings indicated that okra was a functional vegetable and AeP-P-2 was worth studying and developing into antioxidant component.

Effect of steam explosion pretreatment on the structure and bioactivity of Ampelopsis grossedentata polysaccharides.

Steam explosion (SE) was a friendly environmentally pretreatment method. In this study, the effect of steam explosion (SE) pretreatment on structure and α-glucosidase inhibitory activity of Ampelopsis grossedentata polysaccharides was evaluated. Two novel polysaccharides (AGP and AGP-SE) were extracted, isolated, purified and analyzed by NMR, FT-IR and methylation. The results indicated that AGP mainly consisted of Rha, Xyl, Glc, and Ara with a molecular weight of 2.74 × 103 kDa and AGP-SE mainly consisted of Man, Ara, and Gal with a molecular weight of 2.14 × 103 kDa. Furthermore, the backbone of AGP and AGP-SE were mainly composed of 5)-Araf-(1→, -Glcp-(1→, 6)-Glcp-(1→, 6)-Galp-(1→, 3,6)-Manp-(1→, and 2,3,6)-Glcp-(1→. Finally, we demonstrated that all polysaccharides exhibited obviously α-glucosidase inhibition activity and mixed type inhibition. AGP-SE had better α-glucosidase inhibition activity and the binding affinity KD on α-glucosidase by using Surface Plasmon Resonance (SPR) than AGP. Overall, SE pretreatment is an effective method for extracting polysaccharide and provides a new idea into the improvement of biological activity.

Identify immune-related genes of adzuki bean weevil (Callosobruchus chinensis) in response to bacteria challenge by transcriptome analysis.

BACKGROUND: Callosobruchus chinensis is one of the important postharvest pests in legume growing areas. Bacterial pesticide is a potential alternative method to control storage pests. However, the effect of these pathogen bacteria on storage pests, and the molecular mechanisms of insect response remain to be to investigated. RESULTS: Using the next generation sequencing technology, we established a transcriptomic library for C. chinensis larvae in response to Escherichia coli. Total of 355 differential expressed genes (DEGs) were identified, which 178 DEGs were upregulated, and 177 DEGs were downregulated compared to control group. To validate the RNA-seq analysis, 20 DEGs and 14 immune-related genes were selected to perform quantitative polymerase chain reaction (RT-qPCR). These immune-related genes were involved in recognition (peptidoglycan recognition proteins), signal transduction (fibrinogen-related proteins, serine proteinases and NF-κB), and execution effectors (phenoloxidase, defensin, attacin, and antimicrobial peptide). In addition, genes that encode digestive and respiratory enzymes were altered in C. chinensis larvae in response to infection. Some genes that involved in juvenile hormone and insulin pathway appeared to express differentially, suggesting that pathogen infection might lead to developmental arrest. Furthermore, iron homeostasis and chitin metabolism appeared significantly altered after infection. CONCLUSION: In this study, we characterized the immune response of C. chinensis larvae in response to E. coli using RNA-seq, from pathogen recognition, signal transduction, to execution. Some other identified genes were involved in iron homeostasis, respiration, and digestion. A better understanding of molecular response of beetle to pathogen will facilitate us to develop an available strategy to control storage pests.

Enzymatic characterization and validation of gene expression of phosphoglucomutase from Cordyceps militaris.

The purification and characterization of PGM (Phosphoglucomutase) from Cordyceps militaris (C. militaris) was investigated. PGM was purified using a combination of ultrafiltration, salting-out and ion exchange chromatography resulting in 4.23-fold enhancement of activity with a recovery of 20.01%. Molecular mass was 50.01 kDa by SDS-PAGE. The optimal activity was achieved at pH 7.5 and 30 °C with NADPH as substrate. The results showed that SDS, DTT Li+, Cu2+, Na+, Mn2+ and Al3+ were effective PGM inhibitors; whereas glycerol, Zn2+, Mg2+, Ca2+, Fe2+ and Fe3+ could enhance the activity of PGM, and the Km and Vmax values were 11.62 mmol/L and 416.67 U/mL, respectively. At the same time, qRT-PCR was used to test the changes of mRNA transcription level of PGM gene encoding under two fermentation conditions: basic medium and optimized medium. The relative quantitative results of PGM target genes resulting in 2.60-fold enhancement than the control group.

Apoplastic Cell Death-Inducing Proteins of Filamentous Plant Pathogens: Roles in Plant-Pathogen Interactions.

Filamentous pathogens, such as phytopathogenic oomycetes and fungi, secrete a remarkable diversity of apoplastic effector proteins to facilitate infection, many of which are able to induce cell death in plants. Over the past decades, over 177 apoplastic cell death-inducing proteins (CDIPs) have been identified in filamentous oomycetes and fungi. An emerging number of studies have demonstrated the role of many apoplastic CDIPs as essential virulence factors. At the same time, apoplastic CDIPs have been documented to be recognized by plant cells as pathogen-associated molecular patterns (PAMPs). The recent findings of extracellular recognition of apoplastic CDIPs by plant leucine-rich repeat-receptor-like proteins (LRR-RLPs) have greatly advanced our understanding of how plants detect them and mount a defense response. This review summarizes the latest advances in identifying apoplastic CDIPs of plant pathogenic oomycetes and fungi, and our current understanding of the dual roles of apoplastic CDIPs in plant-filamentous pathogen interactions.

Inhibition of mitochondrial respiration under hypoxia and increased antioxidant activity after reoxygenation of Tribolium castaneum.

Regulating the air in low-oxygen environments protects hermetically stored grains from storage pests damage. However, pests that can tolerate hypoxic stress pose a huge challenge in terms of grain storage. We used various biological approaches to determine the fundamental mechanisms of Tribolium castaneum to cope with hypoxia. Our results indicated that limiting the available oxygen to T. castaneum increased glycolysis and inhibited the Krebs cycle, and that accumulated pyruvic acid was preferentially converted to lactic acid via anaerobic metabolism. Mitochondrial aerobic respiration was markedly suppressed for beetles under hypoxia, which also might have led to mitochondrial autophagy. The enzymatic activity of citrate synthase decreased in insects under hypoxia but recovered within 12 h, which suggested that the beetles recovered from the hypoxia. Moreover, hypoxia-reperfusion resulted in severe oxidative damage to insects, and antioxidant levels increased to defend against the high level of reactive oxygen species. In conclusion, our findings show that mitochondria were the main target in T. castaneum in response to low oxygen. The beetles under hypoxia inhibited mitochondrial respiration and increased antioxidant activity after reoxygenation. Our research advances the field of pest control and makes it possible to develop more efficient strategies for hermetic storage.