The potential of Burkholderia gladioli KRS027 in plant growth promotion and biocontrol against Verticillium dahliae revealed by dual transcriptome of pathogen and host.

Verticillium dahliae is a destructive, soil-borne pathogen that causes significant losses on numerous important dicots. Recently, beneficial microbes inhabiting the rhizosphere have been exploited and used to control plant diseases. In the present study, Burkholderia gladioli KRS027 demonstrated excellent inhibitory effects against Verticillium wilt in cotton seedlings. Plant growth and development was promoted by affecting the biosynthesis and signaling pathways of brassinosteroids (BRs), gibberellins (GAs), and auxins, consequently promoting stem elongation, shoot apical meristem, and root apical tissue division in cotton. Furthermore, based on the host transcriptional response to V. dahliae infection, it was found that KRS027 modulates the plants to maintain cell homeostasis and respond to other pathogen stress. Moreover, KRS027 induced disruption of V. dahliae cellular structures, as evidenced by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses. Based on the comparative transcriptomic analysis between KRS027 treated and control group of V. dahliae, KRS027 induced substantial alterations in the transcriptome, particularly affecting genes encoding secreted proteins, small cysteine-rich proteins (SCRPs), and protein kinases. In addition, KRS027 suppressed the growth of different clonal lineages of V. dahliae strains through metabolites, and volatile organic compounds (VOCs) released by KRS027 inhibited melanin biosynthesis and microsclerotia development. These findings provide valuable insights into an alternative biocontrol strategy for Verticillium wilt, demonstrating that the antagonistic bacterium KRS027 holds promise as a biocontrol agent for promoting plant growth and managing disease occurrence.

Glycosylation editing: an innovative therapeutic opportunity in precision oncology.

Cancer is still one of the most arduous challenges in the human society, even though humans have found many ways to try to conquer it. With our incremental understandings on the impact of sugar on human health, the clinical relevance of glycosylation has attracted our attention. The fact that altered glycosylation profiles reflect and define different health statuses provide novel opportunities for cancer diagnosis and therapeutics. By reviewing the mechanisms and critical enzymes involved in protein, lipid and glycosylation, as well as current use of glycosylation for cancer diagnosis and therapeutics, we identify the pivotal connection between glycosylation and cellular redox status and, correspondingly, propose the use of redox modulatory tools such as cold atmospheric plasma (CAP) in cancer control via glycosylation editing. This paper interrogates the clinical relevance of glycosylation on cancer and has the promise to provide new ideas for laboratory practice of cold atmospheric plasma (CAP) and precision oncology therapy.

Insights into the biocontrol and plant growth promotion functions of Bacillus altitudinis strain KRS010 against Verticillium dahliae.

BACKGROUND: Verticillium wilt, caused by the fungus Verticillium dahliae, is a soil-borne vascular fungal disease, which has caused great losses to cotton yield and quality worldwide. The strain KRS010 was isolated from the seed of Verticillium wilt-resistant Gossypium hirsutum cultivar "Zhongzhimian No. 2." RESULTS: The strain KRS010 has a broad-spectrum antifungal activity to various pathogenic fungi as Verticillium dahliae, Botrytis cinerea, Fusarium spp., Colletotrichum spp., and Magnaporthe oryzae, of which the inhibition rate of V. dahliae mycelial growth was 73.97% and 84.39% respectively through confrontation test and volatile organic compounds (VOCs) treatments. The strain was identified as Bacillus altitudinis by phylogenetic analysis based on complete genome sequences, and the strain physio-biochemical characteristics were detected, including growth-promoting ability and active enzymes. Moreover, the control efficiency of KRS010 against Verticillium wilt of cotton was 93.59%. After treatment with KRS010 culture, the biomass of V. dahliae was reduced. The biomass of V. dahliae in the control group (Vd991 alone) was 30.76-folds higher than that in the treatment group (KRS010+Vd991). From a molecular biological aspect, KRS010 could trigger plant immunity by inducing systemic resistance (ISR) activated by salicylic acid (SA) and jasmonic acid (JA) signaling pathways. Its extracellular metabolites and VOCs inhibited the melanin biosynthesis of V. dahliae. In addition, KRS010 had been characterized as the ability to promote plant growth. CONCLUSIONS: This study indicated that B. altitudinis KRS010 is a beneficial microbe with a potential for controlling Verticillium wilt of cotton, as well as promoting plant growth.

Transcriptome analysis of Gossypium hirsutum cultivar Zhongzhimian No.2 uncovers the gene regulatory networks involved in defense against Verticillium dahliae.

BACKGROUND: Cotton is globally important crop. Verticillium wilt (VW), caused by Verticillium dahliae, is the most destructive disease in cotton, reducing yield and fiber quality by over 50% of cotton acreage. Breeding resistant cotton cultivars has proven to be an efficient strategy for improving the resistance of cotton to V. dahliae. However, the lack of understanding of the genetic basis of VW resistance may hinder the progress in deploying elite cultivars with proven resistance. RESULTS: We planted the VW-resistant Gossypium hirsutum cultivar Zhongzhimian No.2 (ZZM2) in an artificial greenhouse and disease nursery. ZZM2 cotton was subsequently subjected to transcriptome sequencing after Vd991 inoculation (6, 12, 24, 48, and 72 h post-inoculation). Several differentially expressed genes (DEGs) were identified in response to V. dahliae infection, mainly involved in resistance processes, such as flavonoid and terpenoid quinone biosynthesis, plant hormone signaling, MAPK signaling, phenylpropanoid biosynthesis, and pyruvate metabolism. Compared to the susceptible cultivar Junmian No.1 (J1), oxidoreductase activity and reactive oxygen species (ROS) production were significantly increased in ZZM2. Furthermore, gene silencing of cytochrome c oxidase subunit 1 (COX1), which is involved in the oxidation-reduction process in ZZM2, compromised its resistance to V. dahliae, suggesting that COX1 contributes to VW resistance in ZZM2. CONCLUSIONS: Our data demonstrate that the G. hirsutum cultivar ZZM2 responds to V. dahliae inoculation through resistance-related processes, especially the oxidation-reduction process. This enhances our understanding of the mechanisms regulating the ZZM2 defense against VW.

Functional analysis of the mating type genes in Verticillium dahliae.

BACKGROUND: Populations of the plant pathogenic fungus Verticillium dahliae display a complex and rich genetic diversity, yet the existence of sexual reproduction in the fungus remains contested. As pivotal genes, MAT genes play a crucial role in regulating cell differentiation, morphological development, and mating of compatible cells. However, the functions of the two mating type genes in V. dahliae, VdMAT1-1-1, and VdMAT1-2-1, remain poorly understood. RESULTS: In this study, we confirmed that the MAT loci in V. dahliae are highly conserved, including both VdMAT1-1-1 and VdMAT1-2-1 which share high collinearity. The conserved core transcription factor encoded by the two MAT loci may facilitate the regulation of pheromone precursor and pheromone receptor genes by directly binding to their promoter regions. Additionally, peptide activity assays demonstrated that the signal peptide of the pheromone VdPpg1 possessed secretory activity, while VdPpg2, lacked a predicted signal peptide. Chemotactic growth assays revealed that V. dahliae senses and grows towards the pheromones FO-a and FO-α of Fusarium oxysporum, as well as towards VdPpg2 of V. dahliae, but not in response to VdPpg1. The findings herein also revealed that VdMAT1-1-1 and VdMAT1-2-1 regulate vegetative growth, carbon source utilization, and resistance to stressors in V. dahliae, while negatively regulating virulence. CONCLUSIONS: These findings underscore the potential roles of VdMAT1-1-1 and VdMAT1-2-1 in sexual reproduction and confirm their involvement in various asexual processes of V. dahliae, offering novel insights into the functions of mating type genes in this species.

Characterization of the Endophytic Bacillus subtilis KRS015 Strain for Its Biocontrol Efficacy Against Verticillium dahliae.

Endophytes play important roles in promoting plant growth and controlling plant diseases. Verticillium wilt is a vascular wilt disease caused by Verticillium dahliae, a widely distributed soilborne pathogen that causes significant economic losses on cotton each year. In this study, an endophyte KRS015, isolated from the seed of the Verticillium wilt-resistant Gossypium hirsutum 'Zhongzhimian No. 2', was identified as Bacillus subtilis by morphological, phylogenetic, physiological, and biochemical analyses. The volatile organic compounds (VOCs) produced by KRS015 or its cell-free fermentation extract had significant antagonistic effects on various pathogenic fungi, including V. dahliae. KRS015 reduced Verticillium wilt index and colonization of V. dahliae in treated cotton seedlings significantly; the disease reduction rate was ∼62%. KRS015 also promoted plant growth, potentially mediated by the growth-related cotton genes GhACL5 and GhCPD-3. The cell-free fermentation extract of KRS015 triggered a hypersensitivity response, including reactive oxygen species (ROS) and expression of resistance-related plant genes. VOCs from KRS015 also inhibited germination of conidia and the mycelial growth of V. dahliae, and were mediated by growth and development-related genes such as VdHapX, VdMcm1, Vdpf, and Vel1. These results suggest that KRS015 is a potential agent for controlling Verticillium wilt and promoting growth of cotton.

The Effect of Preventing Oxidative Stress and Its Mechanisms in the Extract from Sonchus brachyotus DC. Based on the Nrf2-Keap1-ARE Signaling Pathway.

As the organ with the largest contact area with the outside world, the intestine is home to a large number of microorganisms and carries out the main functions of food digestion, absorption, and metabolism. Therefore, there is a very active metabolism of substances and energy in the gut, which is easily attacked by oxygen free radicals. What is more, oxidative stress can gradually and slowly cause very serious damage to the gut. Hence, maintaining redox balance is essential for maintaining environmental balance in the gut. Our previous studies have demonstrated that the extract of Sonchus brachyotus DC. (SBE) has been shown to be capable of repairing oxidative damage, while it has not been demonstrated that it can prevent oxidative stress or how it develops. In this work, we investigated the prevention of oxidative stress and its mechanism in SBE based on the H2O2-induced oxidative damage model in Caco-2 cells; the results indicate that SBE can reduce the contents of ROS and MDA and increase the activities of SOD and CAT in preventing oxidative stress. Then, at the mRNA and protein level, SBE can up-regulate and down-regulate the expression of related genes (NFE2L2, KEAP1, HMOX1, NQO1, SOD1, CAT, and GPX1) and proteins involved in the Nrf2-Keap1-ARE signaling pathway. In conclusion, SBE plays a preventive role in oxidative stress through the Nrf2-Keap1-ARE signaling pathway.

Genome-wide identification and analysis of a cotton secretome reveals its role in resistance against Verticillium dahliae.

BACKGROUND: The extracellular space between the cell wall and plasma membrane is a battlefield in plant-pathogen interactions. Within this space, the pathogen employs its secretome to attack the host in a variety of ways, including immunity manipulation. However, the role of the plant secretome is rarely studied for its role in disease resistance. RESULTS: Here, we examined the secretome of Verticillium wilt-resistant Gossypium hirsutum cultivar Zhongzhimian No.2 (ZZM2, encoding 95,327 predicted coding sequences) to determine its role in disease resistance against the wilt causal agent, Verticillium dahliae. Bioinformatics-driven analyses showed that the ZZM2 genome encodes 2085 secreted proteins and that these display disequilibrium in their distribution among the chromosomes. The cotton secretome displayed differences in the abundance of certain amino acid residues as compared to the remaining encoded proteins due to the localization of these putative proteins in the extracellular space. The secretome analysis revealed conservation for an allotetraploid genome, which nevertheless exhibited variation among orthologs and comparable unique genes between the two sub-genomes. Secretome annotation strongly suggested its involvement in extracellular stress responses (hydrolase activity, oxidoreductase activity, and extracellular region, etc.), thus contributing to resistance against the V. dahliae infection. Furthermore, the defense response genes (immunity marker NbHIN1, salicylic acid marker NbPR1, and jasmonic acid marker NbLOX4) were activated to varying degrees when Nicotina benthamiana leaves were agro-infiltrated with 28 randomly selected members, suggesting that the secretome plays an important role in the immunity response. Finally, gene silencing assays of 11 members from 13 selected candidates in ZZM2 displayed higher susceptibility to V. dahliae, suggesting that the secretome members confer the Verticillium wilt resistance in cotton. CONCLUSIONS: Our data demonstrate that the cotton secretome plays an important role in Verticillium wilt resistance, facilitating the development of the resistance gene markers and increasing the understanding of the mechanisms regulating disease resistance.

Functional Characterization of Verticillium dahliae Race 3-Specific Gene VdR3e in Virulence and Elicitation of Plant Immune Responses.

Verticillium dahliae is a soilborne fungal pathogen that causes disease on many economically important crops. Based on the resistance or susceptibility of differential cultivars in tomato, isolates of V. dahliae are divided into three races. Avirulence (avr) genes within the genomes of the three races have also been identified. However, the functional role of the avr gene in race 3 isolates of V. dahliae has not been characterized. In this study, bioinformatics analysis showed that VdR3e, a cysteine-rich secreted protein encoded by the gene characterizing race 3 in V. dahliae, was likely obtained by horizontal gene transfer from the fungal genus Bipolaris. We demonstrate that VdR3e causes cell death by triggering multiple defense responses. In addition, VdR3e localized at the periphery of the plant cell and triggered immunity depending on its subcellular localization and the cell membrane receptor BAK1. Furthermore, VdR3e is a virulence factor and shows differential pathogenicity in race 3-resistant and -susceptible hosts. These results suggest that VdR3e is a virulence factor that can also interact with BAK1 as a pathogen-associated molecular pattern (PAMP) to trigger immune responses. IMPORTANCE Based on the gene-for-gene model, research on the function of avirulence genes and resistance genes has had an unparalleled impact on breeding for resistance in most crops against individual pathogens. The soilborne fungal pathogen, Verticillium dahliae, is a major pathogen on many economically important crops. Currently, avr genes of the three races in V. dahliae have been identified, but the function of avr gene representing race 3 has not been described. We investigated the characteristics of VdR3e-mediated immunity and demonstrated that VdR3e acts as a PAMP to activate a variety of plant defense responses and induce plant cell death. We also demonstrated that the role of VdR3e in pathogenicity was host dependent. This is the first study to describe the immune and virulence functions of the avr gene from race 3 in V. dahliae, and we provide support for the identification of genes mediating resistance against race 3.

Unlocking antagonistic potential of Bacillus amyloliquefaciens KRS005 to control gray mold.

To establish a safe, efficient, and simple biocontrol measure for gray mold disease caused by Botrytis cinerea, the basic characteristics and antifungal activity of KRS005 were studied from multiple aspects including morphological observation, multilocus sequence analysis and typing (MLSA-MLST), physical-biochemical assays, broad-spectrum inhibitory activities, control efficiency of gray mold, and determination of plant immunity. The strain KRS005, identified as Bacillus amyloliquefaciens, demonstrated broad-spectrum inhibitory activities against various pathogenic fungi by dual confrontation culture assays, of which the inhibition rate of B. cinerea was up to 90.3%. Notably, through the evaluation of control efficiency, it was found that KRS005 fermentation broth could effectively control the occurrence of tobacco leaves gray mold by determining the lesion diameter and biomass of B. cinerea on tobacco leaves still had a high control effect after dilution of 100 folds. Meanwhile, KRS005 fermentation broth had no impact on the mesophyll tissue of tobacco leaves. Further studies showed that plant defense-related genes involved in reactive oxygen species (ROS), salicylic acid (SA), and jasmonic acid (JA)-related signal pathways were significantly upregulated when tobacco leaves were sprayed with KRS005 cell-free supernatant. In addition, KRS005 could inhibit cell membrane damage and increase the permeability of B. cinerea. Overall, KRS005, as a promising biocontrol agent, would likely serve as an alternative to chemical fungicides to control gray mold.

Thioredoxin VdTrx1, an unconventional secreted protein, is a virulence factor in Verticillium dahliae.

Understanding how plant pathogenic fungi adapt to their hosts is of critical importance to securing optimal crop productivity. In response to pathogenic attack, plants produce reactive oxygen species (ROS) as part of a multipronged defense response. Pathogens, in turn, have evolved ROS scavenging mechanisms to undermine host defense. Thioredoxins (Trx) are highly conserved oxidoreductase enzymes with a dithiol-disulfide active site, and function as antioxidants to protect cells against free radicals, such as ROS. However, the roles of thioredoxins in Verticillium dahliae, an important vascular pathogen, are not clear. Through proteomics analyses, we identified a putative thioredoxin (VdTrx1) lacking a signal peptide. VdTrx1 was present in the exoproteome of V. dahliae cultured in the presence of host tissues, a finding that suggested that it plays a role in host-pathogen interactions. We constructed a VdTrx1 deletion mutant ΔVdTrx1 that exhibited significantly higher sensitivity to ROS stress, H2O2, and tert-butyl hydroperoxide (t-BOOH). In vivo assays by live-cell imaging and in vitro assays by western blotting revealed that while VdTrx1 lacking the signal peptide can be localized within V. dahliae cells, VdTrx1 can also be secreted unconventionally depending on VdVps36, a member of the ESCRT-II protein complex. The ΔVdTrx1 strain was unable to scavenge host-generated extracellular ROS fully during host invasion. Deletion of VdTrx1 resulted in higher intracellular ROS levels of V. dahliae mycelium, displayed impaired conidial production, and showed significantly reduced virulence on Gossypium hirsutum, and model plants, Arabidopsis thaliana and Nicotiana benthamiana. Thus, we conclude that VdTrx1 acts as a virulence factor in V. dahliae.

Insights into the Biocontrol Function of a Burkholderia gladioli Strain against Botrytis cinerea.

Pathogenic fungi are the main cause of yield loss and postharvest loss of crops. In recent years, some antifungal microorganisms have been exploited and applied to prevent and control pathogenic fungi. In this study, an antagonistic bacteria KRS027 isolated from the soil rhizosphere of a healthy cotton plant from an infected field was identified as Burkholderia gladioli by morphological identification, multilocus sequence analysis, and typing (MLSA-MLST) and physiobiochemical examinations. KRS027 showed broad spectrum antifungal activity against various phytopathogenic fungi by secreting soluble and volatile compounds. KRS027 also has the characteristics of plant growth promotion (PGP) including nitrogen fixation, phosphate, and potassium solubilization, production of siderophores, and various enzymes. KRS027 is not only proven safe by inoculation of tobacco leaves and hemolysis test but also could effectively protect tobacco and table grapes against gray mold disease caused by Botrytis cinerea. Furthermore, KRS027 can trigger plant immunity by inducing systemic resistance (ISR) activated by salicylic acid- (SA), jasmonic acid- (JA), and ethylene (ET)-dependent signaling pathways. The extracellular metabolites and volatile organic compounds (VOCs) of KRS027 affected the colony extension and hyphal development by downregulation of melanin biosynthesis and upregulation of vesicle transport, G protein subunit 1, mitochondrial oxidative phosphorylation, disturbance of autophagy process, and degrading the cell wall of B. cinerea. These results demonstrated that B. gladioli KRS027 would likely become a promising biocontrol and biofertilizer agent against fungal diseases, including B. cinerea, and would promote plant growth. IMPORTANCE Searching the economical, eco-friendly and efficient biological control measures is the key to protecting crops from pathogenic fungi. The species of Burkholderia genus are widespread in the natural environment, of which nonpathogenic members have been reported to have great potential for biological control agents and biofertilizers for agricultural application. Burkholderia gladioli strains, however, need more study and application in the control of pathogenic fungi, plant growth promotion, and induced systemic resistance (ISR). In this study, we found that a B. gladioli strain KRS027 has broad spectrum antifungal activity, especially in suppressing the incidence of gray mold disease caused by Botrytis cinerea, and can stimulate plant immunity response via ISR activated by salicylic acid- (SA), jasmonic acid- (JA), and ethylene (ET)-dependent signaling pathways. These results indicate that B. gladioli KRS027 may be a promising biocontrol and biofertilizer microorganism resource in agricultural applications.

Cyclosporine A-induced gingival overgrowth in renal transplant patients accompanied by epithelial-to-mesenchymal transition.

OBJECTIVE: To investigate the association between the prevalence of cyclosporin A-induced gingival overgrowth and the expression of the epithelial-to-mesenchymal transition factors in the gingival tissues of renal transplant patients. BACKGROUND: Gingival overgrowth (GO) is a frequent complication in organ transplant patients treated with the immunosuppressant cyclosporin A (CsA). The epithelial-to-mesenchymal transition (EMT) is considered a factor contributing to CsA-induced GO. However, current knowledge on this topic is sparse. METHODS: Sixty-three renal transplant patients were divided into two groups according to the occurrence of GO: those with gingival overgrowth (GO+ group) and those without gingival overgrowth (GO- group). Data on age, sex, and use of immunosuppressant and calcium channel blocker medications, serum creatinine values, peak concentrations of blood CsA, and gingival hyperplasia scores were recorded to identify clinically pathogenic factors. Gingival tissues from five patients with CsA-induced GO and five healthy subjects were selected for histomorphological observation with hematoxylin-eosin staining, Masson staining, and immunohistochemical staining. The mRNA expression of EMT factors was detected with reverse transcription-quantitative PCR. RESULTS: The use of CsA significantly increased the prevalence of GO in renal transplant patients. The expression of α-SMA, SMAD4, and TGM2 was upregulated and that of E-cadherin was downregulated in the gingival tissues of patients with CsA-induced GO compared with those of the corresponding controls. CONCLUSION: Treatment with CsA is closely related to the occurrence of GO in renal transplant patients and EMT plays an important role in CsA-induced gingival tissue hyperplasia.

Genome Resource for the Verticillium Wilt Resistant Gossypium hirsutum Cultivar Zhongzhimian No. 2.

Verticillium wilt, caused by the fungal pathogen Verticillium dahliae, is the major cause of disease-related yield losses in cotton (Gossypium hirsutum). Despite these losses, the major cultivars of G. hirsutum remain highly susceptible to Verticillium wilt. The lack of understanding on the genetic basis for Verticillium wilt resistance may further hinder progress in deploying elite cultivars with proven resistance, such as the wilt resistant G. hirsutum cultivar Zhongzhimian No. 2. To help remedy this knowledge gap, we sequenced the whole genome of Zhongzhimian No. 2 and assembled it from a combination of PacBio long reads, Illumina short reads, and high-throughput chromosome conformation capture technologies. The final assembly of the genome was 2.33 Gb, encoding 95,327 predicted coding sequences. The GC content was 34.39% with 99.2% of the bases anchored to 26 pseudo-chromosomes that ranged from 53.8 to 127.7 Mb. This resource will help gain a detailed understanding of the genomic features governing high yield and Verticillium wilt resistance in this cultivar. Comparative genomics will be particularly helpful, since there are several published genomes of other Gossypium species. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

Sleep deprivation affects sex hormones secretion by regulating the expression of the circadian clock gene in the hypothalamus and pituitary via the PI3K/Akt signaling pathway in pregnant rats.

Sleep deprivation (SD) has many deleterious health effects and occurs in more than 70% of pregnant women. However, the changes in sex hormones and relevant mechanisms after SD have not been well clarified. The aim of the present study was to explore the effects of SD on the secretion of sex hormones and the underlying mechanisms. Twelve pregnant Wistar rats were divided into control (CON, n = 6) and SD (n = 6) groups. Pregnant rats in the SD group were deprived of sleep for 18 h, and allowed free rest for 6 h, and then the above procedures were repeated until delivery. The CON group lived in a 12 h light/dark light cycle environment. Estradiol (E2) and progesterone (P4) levels were detected by enzyme-linked immunosorbent assay (ELISA), and the expression of circadian clock genes, Bmal1, Clock and Per2, in hypothalamus and pituitary gland tissues were evaluated by immunohistochemistry (IHC) and reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The PI3K and Akt phosphorylation levels in the hypothalamic and pituitary tissues were determined by Western blot. The results showed that, compared with the CON group, the SD group exhibited significantly reduced serum E2 and P4 levels, down-regulated Bmal1, Clock and Per2 expression, as well as decreased phosphorylation levels of PI3K and Akt. But there was no significant difference of the total PI3K and Akt protein expression levels between the two groups. These results suggest that SD might affect the expression of the circadian clock genes in the hypothalamus and pituitary via PI3K/Akt pathway, and subsequently regulate the secretion of sex hormones in the pregnant rats, which hints the important roles of SD-induced changes of serum sex hormone levels in the pregnant rats.

A polyketide synthase from Verticillium dahliae modulates melanin biosynthesis and hyphal growth to promote virulence.

BACKGROUND: During the disease cycle, plant pathogenic fungi exhibit a morphological transition between hyphal growth (the phase of active infection) and the production of long-term survival structures that remain dormant during "overwintering." Verticillium dahliae is a major plant pathogen that produces heavily melanized microsclerotia (MS) that survive in the soil for 14 or more years. These MS are multicellular structures produced during the necrotrophic phase of the disease cycle. Polyketide synthases (PKSs) are responsible for catalyzing production of many secondary metabolites including melanin. While MS contribute to long-term survival, hyphal growth is key for infection and virulence, but the signaling mechanisms by which the pathogen maintains hyphal growth are unclear. RESULTS: We analyzed the VdPKSs that contain at least one conserved domain potentially involved in secondary metabolism (SM), and screened the effect of VdPKS deletions in the virulent strain AT13. Among the five VdPKSs whose deletion affected virulence on cotton, we found that VdPKS9 acted epistatically to the VdPKS1-associated melanin pathway to promote hyphal growth. The decreased hyphal growth in VdPKS9 mutants was accompanied by the up-regulation of melanin biosynthesis and MS formation. Overexpression of VdPKS9 transformed melanized hyphal-type (MH-type) into the albinistic hyaline hyphal-type (AH-type), and VdPKS9 was upregulated in the AH-type population, which also exhibited higher virulence than the MH-type. CONCLUSIONS: We show that VdPKS9 is a powerful negative regulator of both melanin biosynthesis and MS formation in V. dahliae. These findings provide insight into the mechanism of how plant pathogens promote their virulence by the maintenance of vegetative hyphal growth during infection and colonization of plant hosts, and may provide novel targets for the control of melanin-producing filamentous fungi.

A secreted ribonuclease effector from Verticillium dahliae localizes in the plant nucleus to modulate host immunity.

The arms race between fungal pathogens and plant hosts involves recognition of fungal effectors to induce host immunity. Although various fungal effectors have been identified, the effector functions of ribonucleases are largely unknown. Herein, we identified a ribonuclease secreted by Verticillium dahliae (VdRTX1) that translocates into the plant nucleus to modulate immunity. The activity of VdRTX1 causes hypersensitive response (HR)-related cell death in Nicotiana benthamiana and cotton. VdRTX1 possesses a signal peptide but is unlikely to be an apoplastic effector because its nuclear localization in the plant is necessary for cell death induction. Knockout of VdRTX1 significantly enhanced V. dahliae virulence on tobacco while V. dahliae employs the known suppressor VdCBM1 to escape the immunity induced by VdRTX1. VdRTX1 homologs are widely distributed in fungi but transient expression of 24 homologs from other fungi did not yield cell death induction, suggesting that this function is specific to the VdRTX1 in V. dahliae. Expression of site-directed mutants of VdRTX1 in N. benthamiana leaves revealed conserved ligand-binding sites that are important for VdRTX1 function in inducing cell death. Thus, VdRTX1 functions as a unique HR-inducing effector in V. dahliae that contributes to the activation of plant immunity.

The secretome of Verticillium dahliae in collusion with plant defence responses modulates Verticillium wilt symptoms.

Verticillium dahliae is a notorious soil-borne pathogen that enters hosts through the roots and proliferates in the plant water-conducting elements to cause Verticillium wilt. Historically, Verticillium wilt symptoms have been explained by vascular occlusion, due to the accumulation of mycelia and plant biomacromolecule aggregation, and also by phytotoxicity caused by pathogen-secreted toxins. Beyond the direct cytotoxicity of some members of the secretome, this review systematically discusses the roles of the V. dahliae secretome in vascular occlusion, including the deposition of polysaccharides as an outcome of plant cell wall destruction, the accumulation of fungal mycelia, and modulation of plant defence responses. By modulating plant defences and hormone levels, the secretome manipulates the vascular environment to induce Verticillium wilt. Thus, the secretome of V. dahliae colludes with plant defence responses to modulate Verticillium wilt symptoms, and thereby bridges the historical concepts of both toxin production by the pathogen and vascular occlusion as the cause of wilting symptoms.

Verticillium dahliae CFEM proteins manipulate host immunity and differentially contribute to virulence.

BACKGROUND: Verticillium dahliae is a fungal pathogen that causes a vascular wilt on many economically important crops. Common fungal extracellular membrane (CFEM) domain proteins including secreted types have been implicated in virulence, but their roles in this pathogen are still unknown. RESULTS: Nine secreted small cysteine-rich proteins (VdSCPs) with CFEM domains were identified by bioinformatic analyses and their differential suppression of host immune responses were evaluated. Two of these proteins, VdSCP76 and VdSCP77, localized to the plant plasma membrane owing to their signal peptides and mediated broad-spectrum suppression of all immune responses induced by typical effectors. Deletion of either VdSCP76 or VdSCP77 significantly reduced the virulence of V. dahliae on cotton. Furthermore, VdSCP76 and VdSCP77 suppressed host immunity through the potential iron binding site conserved in CFEM family members, characterized by an aspartic acid residue in seven VdSCPs (Asp-type) in contrast with an asparagine residue (Asn-type) in VdSCP76 and VdSCP77. V. dahliae isolates carrying the Asn-type CFEM members were more virulent on cotton than those carrying the Asp-type. CONCLUSIONS: In the iron-insufficient xylem, V. dahliae is likely to employ the Asp-type CFEM members to chelate iron, and Asn-type CFEM members to suppress immunity, for successful colonization and propagation in host plants.

Impact of advanced maternal age on maternal and neonatal outcomes in preterm birth.

OBJECTIVES: The aim of this study was to investigate the influence of advanced maternal age on the maternal and neonatal outcomes of preterm pregnancies. MATERIAL AND METHODS: The characteristics of patients admitted to the Department of Obstetrics and Gynecology, The First Affiliated Hospital of Fujian Medical University between January 2015 and March, 2019 were retrospectively reviewed. The maternal and neonatal outcomes were compared between advanced maternal age group (≥ 35 years) and younger age group (18-34 years). Statistical analysis was performed by applying the SPSS software. RESULTS: The study population consisted of 986 pregnancies with preterm delivery and 1094 liveborn preterm infants. Multivariate analyses demonstrated that mothers of advanced age were more likely to suffer iatrogenic preterm birth, placenta previa, preeclampsia, gestational diabetes mellitus and postpartum hemorrhage, but less likely to suffer multiple gestation. In terms of neonatal outcomes, advanced maternal age was associated with a decreased rate of low birthweight in an adjusted model without multiple gestation. However, with multiple gestation included in the adjusted model, advanced maternal age was only associated with an increased rate of hyperbilirubinemia. CONCLUSIONS: Advanced maternal age was a risk factor for adverse pregnancy outcomes including iatrogenic preterm birth, placenta previa, preeclampsia, gestational diabetes mellitus, postpartum hemorrhage, and a protective factor for multiple gestation. Regarding neonatal outcomes, advanced maternal age was related to a decreased rate of low birthweight or an increased rate of hyperbilirubinemia depending on the adjustment for multiple gestation.