RESUMEN
Elicited pumpkin was evaluated as a potential daily consumption product able to modulate the gut microbiota. An in vitro dynamic colonic fermentation performance with microbiota from obese volunteers was used. Prebiotic effects were observed after the pumpkin treatment. Bifidobacterium abundance was maintained during the treatment period whereas Lactobacillus increased in the transversal and descending colon. Conversely, Enterobacteriaceae and Clostridium groups were more stable, although scarce decreasing trends were observed for same species. Increments of Lactobacillus acidophilus and Limosilactobacillus fermentum (old Lactobacillus fermentum) were observed in the whole colonic tract after the treatment period. However, modulatory effects were mainly observed in the transversal and descending colon. Diverse bacteria species were increased, such as Akkermansia muciniphila, Bacteroides dorei, Cloacibacillus porcorum, Clostridium lactatifermentans, Ruminococcus albus, Ruminococcus lactaris, Coprococcus catus, Alistipes shahii or Bacteroides vulgatus. The prebiotic effect of the elicited pumpkin was provided by the fiber of the pumpkin, suggesting a release of pectin molecules in the transversal and distal colonic tract through low cellulosic fiber degradation, explaining the increases in the total propionic and butyric acid in these colonic sections. Also, a possible modulatory role of carotenoids from the sample was suggested since carotenes were found in the descending colon. Hence, the results of this research highlighted pumpkin as a natural product able to modulate the microbiota towards a healthier profile.
Asunto(s)
Cucurbita , Fibras de la Dieta , Disbiosis , Microbioma Gastrointestinal , Microbioma Gastrointestinal/efectos de los fármacos , Cucurbita/química , Cucurbita/microbiología , Humanos , Disbiosis/microbiología , Fibras de la Dieta/farmacología , Prebióticos , Fermentación , Masculino , Adulto , Femenino , Colon/microbiología , Colon/metabolismo , Colon/efectos de los fármacosRESUMEN
Cover crops, a soil conservation practice, can contribute to reducing disease pressure caused by Pseudomonas syringae, considered one of the most important bacterial plant pathogens. We recently demonstrated that the phyllosphere (leaf surface) bacterial community structure changed when squash (Cucurbita pepo) was grown with a rye (Secale cereale) cover crop treatment, followed by a decrease of angular leaf spot disease symptoms on squash caused by P. syringae pv. lachrymans. Application of biocontrol agents is a known agricultural practice to mitigate crop losses due to microbial disease. In this study, we tested the hypothesis that some phyllosphere bacteria promoted when squash is grown on cover crops could be isolated and used as a biocontrol agent to decrease angular leaf spot symptoms. We grew squash during a 2-year field experiment using four agricultural practices: bare soil, cover crops, chemically terminated cover crops, and plastic cover. We sampled squash leaves at three different dates each year and constructed a collection of cultivable bacterial strains isolated from squash leaves and rye cover crop material. Each isolated strain was identified by 16S rRNA gene sequencing and used in in vitro (Petri dish) pathogen growth and in vivo (greenhouse) symptom control assays. Four bacterial isolates belonging to the genera Pseudarthrobacter, Pseudomonas, Delftia, and Rhizobium were shown to inhibit P. syringae pv. lachrymans growth and angular leaf spot symptom development. Strikingly, the symptom control efficacy of all strains was stronger on older leaves. This study sheds light on the importance of bacterial isolation from cover crop sources to promote disease control. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
Asunto(s)
Cucurbita , Enfermedades de las Plantas , Hojas de la Planta , Pseudomonas syringae , Secale , Cucurbita/microbiología , Enfermedades de las Plantas/microbiología , Enfermedades de las Plantas/prevención & control , Secale/microbiología , Pseudomonas syringae/fisiología , Pseudomonas syringae/patogenicidad , Hojas de la Planta/microbiología , Productos Agrícolas/microbiología , Bacterias/clasificación , Bacterias/aislamiento & purificación , Bacterias/genética , Bacterias/crecimiento & desarrolloRESUMEN
Fungi, bacteria, and viruses cause highly devastating diseases in species of the Cucurbitaceae family. Powdery mildew, a fungal disease, is one of the most important diseases of cucurbits. The pathogen, Podosphaera xanthii, is the most common causal agent of powdery mildew disease within cucurbits. The aim of this study was to investigate the effectiveness of the combined formulations of two biological agents, B. subtilis and B. thuringiensis, in combating powdery mildew disease, which represents a significant threat to C. pepo cultivation in Kayseri, Türkiye. The efficacy of six different treatments in controlling the disease agent P. xanthii was evaluated in susceptible zucchini genotypes. It was found that full-dose bacteria dilution application, before and after powdery mildew infection, as well as three- and five-fold bacteria dilutions application significantly prevented (1-2 scale value) powdery mildew disease on infected zucchini plants than the control application. There was a decrease in vegetative growth in the control-treated crops while plant growth increased significantly in bacterial-treated crops. Also, our findings showed that combined formulations made from Bacillus subtilis (61.29e and 3.3a strains) and Bacillus thuringiensis (2B3-1 and 2B2-2 strains) significantly increased the synthesis of plant defense enzymes such as DPPH, antioxidant, proline production, total phenolic substance, and total flavonoid content. The application of B + PM resulted in the highest enzyme contents, quantified as follows: 22.91 mg AAE/g antioxidant, 2.01 mg/g KU proline, 10.03 mg GAE/g TPC, and 7.756 mg CE/g TFC. These enzymes may have played vital roles in triggering zucchini defense mechanisms, thereby significantly preventing powdery disease in the bacteria-treated crops.
Asunto(s)
Bacillus thuringiensis , Cucurbita , Cucurbita/microbiología , Bacillus subtilis , Antioxidantes , ProlinaRESUMEN
The predicted repertoire of type III secretion system effectors (T3SEs) in Erwinia tracheiphila, causal agent of cucurbit bacterial wilt, is much larger than in xylem pathogens in the closely related genera Erwinia and Pantoea. The genomes of strains BHKY and SCR3, which represent distinct E. tracheiphila clades, encode at least 6 clade-specific and 12 shared T3SEs. The strains expressed the majority of the T3SE genes examined in planta. Among the shared T3SE genes, eop1 was expressed most highly in both strains in squash (Cucurbita pepo) and muskmelon (Cucumis melo) but the clade-specific gene avrRpm2 was expressed 40- to 900-fold more than eop1 in BHKY. The T3SEs AvrRpm2, Eop1, SrfC, and DspE contributed to BHKY virulence on squash and muskmelon, as shown using combinatorial mutants involving six T3SEs, whereas OspG and AvrB4 contributed to BHKY virulence only on muskmelon, demonstrating host-specific virulence functions. Moreover, Eop1 was functionally redundant with AvrRpm2, SrfC, OspG, and AvrB4 in BHKY, and BHKY mutants lacking up to five effector genes showed similar virulence to mutants lacking only two genes. The T3SEs OspG, AvrB4, and DspE contributed additively to SCR3 virulence on muskmelon and were not functionally redundant with Eop1. Rather, loss of eop1 and avrB4 restored wild-type virulence to the avrB4 mutant, suggesting that Eop1 suppresses a functionally redundant effector in SCR3. These results highlight functional differences in effector inventories between two E. tracheiphila clades, provide the first evidence of OspG as a phytopathogen effector, and suggest that Eop1 may be a metaeffector influencing virulence. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.
Asunto(s)
Cucurbita , Erwinia , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Cucurbita/microbiología , Erwinia/genética , Erwinia/metabolismo , Enfermedades de las Plantas/microbiología , Sistemas de Secreción Tipo III/genética , XilemaRESUMEN
The aim of this study was to uncover the molecular mechanism through which fungicide resistance develops in Podosphaera xanthii, a fungi that causes powdery mildew in hull-less pumpkin. Treatments of inoculated P. xanthii were carried out on leaves of hull-less pumpkin and subsequently treated with kinds of triazole fungicide for seven generations. Resistant strains of P. xanthii thus obtained were evaluated for their resistance levels. The resistance levels of the fungi to four fungicides of were high except that of the propiconazole-resistant strain, which showed moderate resistance. The F7 generations of five resistant strains thus obtained were cultured continuously for five generations without fungicide induction, and their resistance level were found to be relatively stable. The DNA of the sensitive strain and the five kinds of resistant strains were extracted by the sodium dodecyl sulfate (SDS) method and its internal transcribed spacer (ITS) region was amplified by using ITS1/ITS4 primer and specific primer F/R and they were sequenced respectively. The DNA sequence comparison of resistant and sensitive strains showed that the base pairs of tebuconazole-resistant strains and flusilazole-resistant strains were mutated, with mutation rates of 4.8% and 1.6%, respectively. The base pairs of the other three resistant strains did not change.
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Antifúngicos/farmacología , Ascomicetos/genética , Farmacorresistencia Fúngica/efectos de los fármacos , Enfermedades de las Plantas/microbiología , Triazoles/farmacología , Ascomicetos/fisiología , Cucurbita/genética , Cucurbita/microbiología , Farmacorresistencia Fúngica/genética , Enfermedades de las Plantas/genética , Hojas de la Planta/genética , Hojas de la Planta/microbiología , Silanos/farmacologíaRESUMEN
To increase agriculture production, accurate and fast detection of plant disease is required. Expert advice is needed to detect disease in plants, nutrition deficiencies or any other abnormalities caused by extreme weather conditions. But this process is very tedious, costly, and takes more time. In this paper, hyperspectral imaging and machine learning were used to detect different stages (early, middle, and critical stage) of the powderly mildew disease (PMD) in squash plants. An unmanned aerial vehicle (UAV) was used to collect the data from the field and Locality Preserving Discriminative Broad Learning (LPDBL) was used to distinguish the diseased and healthy plants. In addition, the ability to detect the diseased plant by the proposed method was evaluated using 10 different spectral vegetation indices (VIs). The results show the proposed method detected the disease accurately in the early, middle, and critical stages of the squash plant. The proposed method's performance is compared with six different PMDs under indoor laboratory test and UAV-based field test conditions. The comparison's results show that the LPDBL provides better accuracy in detecting disease in the squash plant.
Asunto(s)
Cucurbita/microbiología , Aprendizaje Automático , Enfermedades de las Plantas/microbiología , Dispositivos Aéreos No Tripulados , Agricultura/métodos , Cucurbita/crecimiento & desarrollo , Análisis Discriminante , Procesamiento de Imagen Asistido por Computador/métodos , Hojas de la Planta/microbiologíaRESUMEN
Powdery mildew (PM) disease, caused by the obligate biotrophic fungal pathogen Podosphaera xanthii, is the most reported and destructive disease on cultivated Cucurbita species all over the world. Recently, the appearance of highly aggressive P. xanthii isolates has led to PM outbreaks even in resistant crops, making disease management a very difficult task. To challenge this, breeders rely on genetic characteristics for PM control. Analysis of commercially available intermediate resistance courgette (Cucurbita pepo L. var. cylindrica) varieties using cytological, molecular, and biochemical approaches showed that the plants were under a primed state and induced systemic acquired resistance (SAR) responses, exhibiting enhanced callose production, upregulation of salicylic acid (SA) defense signaling pathway genes, and accumulation of SA and defense metabolites. Additionally, the intermediate resistant varieties showed an altered epigenetic landscape in histone marks that affect transcriptional activation. We demonstrated that courgette plants had enriched H3K4me3 marks on SA-BINDING PROTEIN 2 and YODA (YDA) genes of the Pm-0 interval introgression, a genomic region that confers resistant to Cucurbits against P. xanthii. The open chromatin of SA-BINDING PROTEIN 2 and YDA genes was consistent with genes' differential expression, induced SA pathway, altered stomata characteristics, and activated SAR responses. These findings demonstrate that the altered epigenetic landscape of the intermediate resistant varieties modulates the activation of SA-BINDING PROTEIN 2 and YDA genes leading to induced gene transcription that primes courgette plants.
Asunto(s)
Ascomicetos/patogenicidad , Cucurbita/genética , Cucurbita/microbiología , Resistencia a la Enfermedad/genética , Enfermedades de las Plantas/genética , Productos Agrícolas/genética , Productos Agrícolas/microbiología , Regulación de la Expresión Génica de las Plantas , Genes de Plantas , Variación Genética , GenotipoRESUMEN
A novel acidophilic actinobacterium, designated strain NEAU-YB345T, was isolated from a pumpkin root collected from Mudanjiang, Heilongjiang Province, northeast PR China. Based on 16S rRNA gene sequence similarity and chemotaxonomic and morphological properties, the isolate was assigned to the genus Streptacidiphilus, with the high 16S rRNA gene sequence similarities to Streptacidiphilus melanogenes JCM 16224T (99.2 %), Streptacidiphilus anmyonensis JCM 16223T (99.1â%) and Streptacidiphilus jiangxiensis JCM 12277T (98.7â%). Its cell wall contained ll-diaminopimelic acid as the major diamino acid. Rhamnose, ribose, glucose and galactose were the detected sugars from the whole-cell hydrolysates. The phospholipid profile consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannoside and an unidentified phospholipid. The menaquinones were MK-9(H8) and MK-9(H6). Major fatty acids were C16â:â0, iso-C16â:â0, iso-C15â:â0 and anteiso-C15â:â0. Phylogenetic analysis using 16S rRNA gene and whole-genome sequences placed the strain in distinct clades but within the genus Streptacidiphilus. The DNA G+C content was 71.2 mol%. Based on DNA-DNA relatedness and physiological and biochemical data, the isolate could be distinguished from its closest relatives. Therefore, strain NEAU-YB345T represents a novel species of the genus Streptacidiphilus, for which the name Streptacidiphilus fuscans sp. nov. is proposed. The type strain is NEAU-YB345T (=CCTCC AA 2020030T=JCM 33976T).
Asunto(s)
Actinobacteria/aislamiento & purificación , Cucurbita/microbiología , Raíces de Plantas/microbiología , Actinobacteria/genética , Actinobacteria/crecimiento & desarrollo , Actinobacteria/ultraestructura , Secuencia de Bases , ADN Bacteriano/genética , Genoma Bacteriano , Filogenia , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , Especificidad de la EspecieRESUMEN
Sub-Saharan region is often characterized by food and nutrition insecurity especially "hidden hunger" which results from inadequate micronutrients in diets. African indigenous leafy vegetables (AILVs) can represent a valid food source of micronutrients, but they often go to waste resulting in post-harvest losses. In an attempt to prolong AILVs shelf-life while enhancing their nutritional quality, fermentation was studied from a microbiological and nutritional point of view. Pumpkin leaves (Cucurbita sp.) were spontaneously fermented using the submerged method with 3% NaCl and 3% sucrose. Controls were set up, consisting of leaves with no additions. During fermentation, samples of both treatments were taken at 0, 24, 48, 72 and 168 h to monitor pH and characterize the microbial population through culture-based and molecular-based analyses. Variations between fresh and treated leaves in B-group vitamins, carotenoids, polyphenols, and phytic acid were evaluated. Data revealed that the treatment with addition of NaCl and sucrose hindered the growth of undesired microorganisms; in controls, unwanted microorganisms dominated the bacterial community until 168 h, while in treated samples Lactobacillaceae predominated. Furthermore, the content in folate, ß-carotene and lutein increased in treated leaves compared to the fresh ones, while phytic acid diminished indicating an amelioration in the nutritional value of the final product. Thus, fermentation could help in preserving Cucurbita sp. leaves, avoiding contamination of spoilage microorganisms and enhancing the nutritional values.
Asunto(s)
Cucurbita/química , Alimentos Fermentados/análisis , Hojas de la Planta/química , Verduras/química , Carotenoides/análisis , Carotenoides/metabolismo , Cucurbita/microbiología , Fermentación , Alimentos Fermentados/microbiología , Seguridad Alimentaria , Lactobacillaceae/metabolismo , Valor Nutritivo , Hojas de la Planta/microbiología , Verduras/microbiología , Vitaminas/análisis , Vitaminas/metabolismoRESUMEN
KEY MESSAGE: Powdery mildew resistance in zucchini is controlled by one major dominant locus, CpPM10.1. CpPM10.1 was fine mapped. The expression of candidate gene Cp4.1LG10g02780 in resistant individuals was significantly upregulated after inoculation with the powdery mildew. Powdery mildew (PM) is one of the most destructive fungal diseases, reducing the productivity of Cucurbita crops globally. PM influences the photosynthesis, growth and development of infected zucchini and seriously reduces fruit yield and quality. In the present study, the zucchini inbred line 'X10' had highly stable PM resistance, and the inbred line 'Jin234' was highly susceptible to PM in the seedling stage and adult stages. Genetic analysis revealed that PM resistance in 'X10' is controlled by one major dominant locus. Based on the strategy of QTL-seq combined with linkage analysis and developed molecular markers, the major locus was found to be located in a 382.9-kb candidate region on chromosome 10; therefore, the major locus was named CpPM10.1. Using 1,400 F2 individuals derived from a cross between 'X10' and 'JIN234' and F2:3 offspring of the recombinants, the CpPM10.1 locus was defined in a region of approximately 20.9 kb that contained 5 coding genes. Among them, Cp4.1LG10g02780 contained a conserved domain (RPW8), which controls resistance to a broad range of PM pathogens. Cp4.1LG10g02780 also had nonsynonymous SNPs between the resistant 'X10' and susceptible 'Jin234.' Furthermore, the expression of Cp4.1LG10g02780 was strongly positively involved in PM resistance in the key period of inoculation. Further allelic diversity analysis in zucchini germplasm resources indicated that PM resistance was associated with two SNPs in the Cp4.1LG10g02780 RPW8 domain. This study not only provides highly stable PM resistance gene resources for cucurbit crops but also lays the foundation for the functional analysis of PM resistance and resistance breeding in zucchini.
Asunto(s)
Ascomicetos/fisiología , Mapeo Cromosómico/métodos , Cromosomas de las Plantas/genética , Cucurbita/genética , Resistencia a la Enfermedad/inmunología , Enfermedades de las Plantas/inmunología , Proteínas de Plantas/metabolismo , Cucurbita/crecimiento & desarrollo , Cucurbita/microbiología , Resistencia a la Enfermedad/genética , Regulación de la Expresión Génica de las Plantas , Enfermedades de las Plantas/genética , Enfermedades de las Plantas/microbiología , Proteínas de Plantas/genéticaRESUMEN
Essential oils are gaining interest as environmentally friendly alternatives to synthetic fungicides for management of seedborne pathogens. Here, seven essential oils were initially tested in vivo for disinfection of squash seeds (Cucurbita maxima) naturally contaminated by Stagonosporopsis cucurbitacearum, Alternaria alternata, Fusarium fujikuro, Fusarium solani, Paramyrothecium roridum, Albifimbria verrucaria, Curvularia spicifera, and Rhizopus stolonifer. The seeds were treated with essential oils from Cymbopogon citratus, Lavandula dentata, Lavandula hybrida, Melaleuca alternifolia, Laurus nobilis, and Origanum majorana (#1 and #2). Incidence of S. cucurbitacearum was reduced, representing a range between 67.0% in L. nobilis to 84.4% in O. majorana #2. Treatments at 0.5 mg/mL essential oils did not affect seed germination, although radicles were shorter than controls, except with C. citratus and O. majorana #1 essential oils. Four days after seeding, seedling emergence was 20%, 30%, and 10% for control seeds and seeds treated with C. citratus essential oil (0.5 mg/mL) and fungicides (25 g/L difenoconazole plus 25 g/L fludioxonil). S. cucurbitacearum incidence was reduced by ~40% for plantlets from seeds treated with C. citratus essential oil. These data show the effectiveness of this essential oil to control the transmission of S. cucurbitacearum from seeds to plantlets, and thus define their potential use for seed decontamination in integrated pest management and organic agriculture.
Asunto(s)
Cucurbita/microbiología , Aceites Volátiles/farmacología , Aceites de Plantas/farmacología , Semillas/efectos de los fármacos , Alternaria/efectos de los fármacos , Alternaria/patogenicidad , Ascomicetos/patogenicidad , Cucurbita/efectos de los fármacos , Curvularia/efectos de los fármacos , Curvularia/patogenicidad , Fungicidas Industriales/química , Fungicidas Industriales/farmacología , Fusarium/efectos de los fármacos , Fusarium/patogenicidad , Hypocreales/efectos de los fármacos , Hypocreales/patogenicidad , Aceites Volátiles/química , Enfermedades de las Plantas/microbiología , Enfermedades de las Plantas/prevención & control , Aceites de Plantas/química , Rhizopus/efectos de los fármacos , Rhizopus/patogenicidad , Semillas/microbiologíaRESUMEN
Podosphaera xanthii is the main causal agent of cucurbit powdery mildew and a limiting factor of crop productivity. The lifestyle of this fungus is determined by the development of specialized parasitic structures inside epidermal cells, termed haustoria, that are responsible for the acquisition of nutrients and the release of effectors. A typical function of fungal effectors is the manipulation of host immunity, for example the suppression of pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI). Chitin is a major component of fungal cell walls, and chitin oligosaccharides are well-known PAMP elicitors. In this work, we examined the role of PHEC27213, the most highly expressed, haustorium-specific effector candidate of P. xanthii. According to different computational predictions, the protein folding of PHEC27213 was similar to that of lytic polysaccharide monooxygenases (LPMOs) and included a conserved histidine brace; however, PHEC27213 had low sequence similarity with LPMO proteins and displayed a putative chitin-binding domain that was different from the canonical carbohydrate-binding module. Binding and enzymatic assays demonstrated that PHEC27213 was able to bind and catalyse colloidal chitin, as well as chitooligosaccharides, acting as an LPMO. Furthermore, RNAi silencing experiments showed the potential of this protein to prevent the activation of chitin-triggered immunity. Moreover, proteins with similar features were found in other haustorium-forming fungal pathogens. Our results suggest that this protein is a new fungal LPMO that catalyses chitooligosaccharides, thus contributing to the suppression of plant immunity during haustorium development. To our knowledge, this is the first mechanism identified in the haustorium to suppress chitin signalling.
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Ascomicetos/enzimología , Quitina/análogos & derivados , Quitina/inmunología , Cucurbita/microbiología , Oxigenasas de Función Mixta/metabolismo , Enfermedades de las Plantas/microbiología , Ascomicetos/genética , Ascomicetos/fisiología , Quitosano , Cucurbita/inmunología , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Oxigenasas de Función Mixta/genética , Modelos Moleculares , Simulación del Acoplamiento Molecular , Oligosacáridos , Moléculas de Patrón Molecular Asociado a Patógenos/inmunología , Enfermedades de las Plantas/inmunología , Inmunidad de la Planta , Transducción de SeñalRESUMEN
KEY MESSAGE: Two QTL mapping approaches were used to identify a total of six QTL associated with Phytophthora root and crown rot resistance in a biparental squash population. Phytophthora root and crown rot, caused by the soilborne oomycete pathogen Phytophthora capsici, leads to severe yield losses in squash (Cucurbita pepo). To identify quantitative trait loci (QTL) involved in resistance to this disease, we crossed a partially resistant squash breeding line with a susceptible zucchini cultivar and evaluated over 13,000 F2 seedlings in a greenhouse screen. Bulked segregant analysis with whole genome resequencing (BSA-Seq) resulted in the identification of five genomic regions-on chromosomes 4, 5, 8, 12, and 16-featuring significant allele frequency differentiation between susceptible and resistant bulks in each of two independent replicates. In addition, we conducted linkage mapping using a population of 176 F3 families derived from individually genotyped F2 individuals. Variation in disease severity among these families was best explained by a four-QTL model, comprising the same loci identified via BSA-Seq on chromosomes 4, 5, and 8 as well as an additional locus on chromosome 19, for a combined total of six QTL identified between both methods. Loci, whether those identified by BSA-Seq or linkage mapping, were of small-to-moderate effect, collectively accounting for 28-35% and individually for 2-10% of the phenotypic variance explained. However, a multiple linear regression model using one marker in each BSA-Seq QTL could predict F2:3 disease severity with only a slight drop in cross-validation accuracy compared to genomic prediction models using genome-wide markers. These results suggest that marker-assisted selection could be a suitable approach for improving Phytophthora crown and root rot resistance in squash.
Asunto(s)
Mapeo Cromosómico/métodos , Cucurbita/genética , Resistencia a la Enfermedad/genética , Genoma de Planta , Phytophthora/fisiología , Raíces de Plantas/genética , Polimorfismo de Nucleótido Simple , Cromosomas de las Plantas/genética , Cucurbita/microbiología , Resistencia a la Enfermedad/inmunología , Marcadores Genéticos , Genómica , Fenotipo , Fitomejoramiento , Enfermedades de las Plantas/genética , Enfermedades de las Plantas/microbiología , Raíces de Plantas/microbiología , Sitios de Carácter CuantitativoRESUMEN
Podosphaera xanthii is the main causal agent of powdery mildew in cucurbits and, arguably, the most important fungal pathogen of cucurbit crops. Here, we present the first reference genome assembly for P. xanthii. We performed a hybrid genome assembly, using reads from Illumina NextSeq550 and PacBio Sequel S3. The short and long reads were assembled into 1,727 scaffolds with an N50 size of 163,173 bp, resulting in a 142-Mb genome size. The combination of homology-based and ab initio predictions allowed the prediction of 14,911 complete genes. Repetitive sequences comprised 76.2% of the genome. Our P. xanthii genome assembly improves considerably the molecular resources for research on P. xanthii-cucurbit interactions and provides new opportunities for further genomics, transcriptomics, and evolutionary studies in powdery mildew fungi.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
Asunto(s)
Ascomicetos , Biología Computacional , Cucurbita , Genoma de Planta , Ascomicetos/genética , Cucurbita/microbiología , Enfermedades de las Plantas/genética , Enfermedades de las Plantas/microbiologíaRESUMEN
Erwinia tracheiphila is a bacterial plant pathogen that causes a fatal wilt infection in some cucurbit crop plants. Wilt symptoms are thought to be caused by systemic bacterial colonization through xylem that impedes sap flow. However, the genetic determinants of within-plant movement are unknown for this pathogen species. Here, we find that E. tracheiphila has horizontally acquired an operon with a microbial expansin (exlx) gene adjacent to a glycoside hydrolase family 5 (gh5) gene. Plant inoculation experiments with deletion mutants in the individual genes (Δexlx and Δgh5) and the full operon (Δexlx-gh5) resulted in decreased severity of wilt symptoms, decreased mortality rate, and impaired systemic colonization compared to the Wt strain. Co-inoculation experiments with Wt and Δexlx-gh5 rescued the movement defect of the mutant strain, suggesting that expansin and GH5 function extracellularly. Together, these results show that expansin-GH5 contributes to systemic movement through xylem, leading to rapid wilt symptom development and higher rates of plant death. The presence of expansin genes in diverse species of bacterial and fungal wilt-inducing pathogens suggests that microbial expansin proteins may be an under-appreciated virulence factor for many pathogen species.
Asunto(s)
Cucurbita/genética , Cucurbita/microbiología , Erwinia/genética , Erwinia/patogenicidad , Enfermedades de las Plantas/genética , Enfermedades de las Plantas/microbiología , Proteínas de Plantas/genética , Interacciones Microbiota-Huesped , Operón/genética , Virulencia , Factores de Virulencia , XilemaRESUMEN
Outbreaks of gummy stem blight (GSB), an emerging seed pumpkin disease, have increased in number and have become more widespread in recent years. Previously we reported that Stagonosporopsis cucurbitacearum (Sc.) is the dominant fungal cause of pumpkin seedling GSB in Northeast China, where it has greatly reduced crop yields in that region. Here, high-throughput whole-genome sequencing and assembly of the Sc. genome were conducted toward revealing pathogenic molecular regulatory mechanisms involved in fungal growth and development. Zq-1 as representative Sc. strain, DNA of Zq-1was prepared for genomic sequencing, we obtained 5.24 Gb of high-quality genomic sequence data via PacBio RS II sequencing. After sequence data was processed to filter out low quality reads, a hierarchical genome-assembly process was employed that generated a genome sequence of 35.28 Mb in size. A total of 9844 genes were predicted, including 237 non-coding RNAs, 1024 genes encoding proteins with signal peptides, 2066 transmembrane proteins and 756 secretory proteins.Transcriptional identification revealed 54 differentially expressed secretory proteins. Concurrently, 605, 130 and 2869 proteins were matched in the proprietary databases Carbohydrate-Active EnZymes database (CAZyme), Transporter Classification Database (TCDB) and Pathogen-Host Interactions database (PHI), respectively. And 96 and 36 DEGs were identified form PHI database and CAZyme database, respectively. In addition, contig00011.93 was an up-regulated DEG involving ATP-binding cassette metabolism in the procession of infection. In order to test relevance of gene predictions to GSB, DEGs with potential pathogenic relevance were revealed through transcriptome data analysis of Sc. strains pre- and post-infection of pumpkin. Interestingly, Sc. and Leptosphaeria maculans (Lm.) exhibited relatively similar with genome lengths, numbers of protein-coding genes and other characteristics. This work provides a foundation for future exploration of additional Sc. gene functions toward the development of more effective GSB control strategies.
Asunto(s)
Ascomicetos/genética , Ascomicetos/patogenicidad , Cucurbita/microbiología , Genoma Fúngico/genética , Enfermedades de las Plantas/microbiología , Ascomicetos/crecimiento & desarrollo , China , Producción de Cultivos , Interacciones Huésped-Patógeno/genética , Secuenciación Completa del GenomaRESUMEN
Verticillium dahliae is a significant pathogen in cucurbit cropping systems for which there are limited control options outside of soil fumigation. Endophytes, fungi and bacteria that live within plant hosts without impacting the host negatively, have exhibited antagonism to V. dahliae. The objectives of this study were to survey potential V. dahliae-antagonistic endophytes from roots of 'Cinnamon Girl' pumpkin (Cucurbita pepo) grown under either polyethylene (PE), an experimental polylactic acid/ poly(hydroxalkanoate) (PLA/PHA) mulch, Weed Guard Plus, or no mulch, as well as from 'Sugar Baby' watermelon (Citrullus lanatus), and 'Tetsukabuto' squash (C. maxima x C. moschata). Four selected endophytes were screened for antagonism against V. dahliae in the laboratory, greenhouse, and field. A total of 777 isolates of potential fungal endophytes were recovered from pumpkin, watermelon, and squash roots between 2015 and 2016 of which 198 isolates were identified down to the genus level. Of those isolates, frequency of isolation was greatest for Dichotomopilus/Chaetomium spp. (5%), Cladosporium spp. (15.2 %), Clonostachys spp. (5.6 %), Epicoccum spp. (22.2 %), and Fusarium spp. (24.7 %). All five genera only weakly associated with roots grown under a particular mulch treatment (Cramer's V = 0.22) or cucurbit host (Cramer's V = 0.1925). In a laboratory culture plate assay, V. dahliae isolate JAW-113 was plated against one of four prospective endophytes (Dichotomopilus sp., Epicoccum sp., Microdochium sp., or Schizothecium sp.). The area under the Verticillium culture growth curve (AUVGC) was significantly highest (P < 0.0001) when V. dahliae was by Schizothecium sp. or Dichotomopilus sp. In a greenhouse study using a Mason jar assay with V. dahliae amended potting mix, pumpkin plant vigor, plant fresh weight, root fresh weight, and root dry weight were significantly higher (P < 0.05) for plants inoculated with Dichotomopilus sp., Epicoccum sp., Microdochium sp., and Schizothecium sp. compared to plants without endophyte inoculation. Subsequent field trials in 2017 and 2018 showed no significant differences in foliar disease severity or fruit yield, regardless of whether plants were inoculated with an endophyte or not. However, recovery of V. dahliae colony forming units from pumpkin stem sap was significantly lower (P < 0.0001) for plants inoculated with either Dichotomopilus sp. or Schizothecium sp. in 2017 or Dichotomopilus sp. in 2018.
Asunto(s)
Ascomicetos/fisiología , Cucurbita/crecimiento & desarrollo , Cucurbita/microbiología , Endófitos/fisiología , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/microbiología , Endófitos/aislamiento & purificación , Fusarium , Enfermedades de las Plantas/microbiología , Microbiología del Suelo , Verticillium , WashingtónRESUMEN
The environment is the key factor that influences the host-parasite relationship. Elevated CO2 levels resulting from various anthropogenic sources may directly affect the surroundings around pathogens and plants. It is hypothesized that plants may respond differently to pathogens in the environment containing an elevated concentration of CO2. To test the hypothesis an experiment was conducted to examine the effects of intermittent exposures of elevated levels of CO2 viz., 400, 500 and 600 ppm (5 hr/day on alternate days) on the development of Sphaerotheca fuliginea causing powdery mildew disease on five cucurbits species using open-top chambers. The elevated levels of CO2 acted as a growth promoter and significantly enhanced the plant growth of all five cucurbit species. Inoculation with the fungus incited specific mildew symptoms on the leaves and decreased the plant growth and biomass production of the cucurbits tested except bitter gourd. The intermittent exposures with elevated levels of CO2 aggravated the disease development. As a result, severe mildew developed on all five cucurbits, including bitter gourd, which expressed tolerance to the pathogen. Fungus colonization in terms of the number of conidia/cm2 leaf surface was significantly greater on the plants exposed to 500 or 600 ppm CO2. The stomata and trichome density and stomatal pore width were increased in the leaves of CO2 exposed plants. The CO2 exposures also accelerated the photosynthesis rate, but transpiration, stomatal conductance, salicylic acid and total phenols were decreased; fungus inoculation caused the effects just reverse of CO2. Interaction between S. fuliginea and CO2 was found synergistic at 500 ppm, whereas with rest of the concentrations it was near to additive.
Asunto(s)
Ascomicetos/crecimiento & desarrollo , Ascomicetos/patogenicidad , Dióxido de Carbono/efectos adversos , Cucurbita/crecimiento & desarrollo , Cucurbita/microbiología , Exposición a Riesgos Ambientales/efectos adversos , Interacciones Huésped-Patógeno/fisiología , Cucurbita/metabolismo , Interacciones Huésped-Patógeno/efectos de los fármacos , Fenoles/metabolismo , Fotosíntesis/efectos de los fármacos , Hojas de la Planta/crecimiento & desarrollo , Hojas de la Planta/metabolismo , Estomas de Plantas/metabolismo , Ácido Salicílico/metabolismo , Tricomas/metabolismoRESUMEN
Phytophthora capsici Leonian, the causal agent of foliar blight, root rot, fruit rot and crown rot syndromes in squash (Cucurbita moschata), is a devastating pathogen worldwide. Resistance to Phytophthora crown rot in University of Florida breeding line #394-1-27-12 (C. moschata) is conferred by three independent dominant genes (R1R2R3). Availability of DNA markers linked to R1R2R3 genes would allow efficient breeding for Phytophthora crown rot resistance through marker-assisted selection (MAS). The goal of the current study was to identify quantitative trait loci (QTLs) associated with resistance to Phytophthora crown rot in an F2 population (n = 168) derived from a cross between #394-1-27-12 (R) and Butter Bush (S) using QTL-seq bulk segregant analysis. Whole-genome resequencing of the resistant (n = 20) and susceptible (n = 20) bulk segregants revealed ~900,000 single nucleotide polymorphisms distributed across C. moschata genome. Three QTLs significantly (P < 0.05) associated with resistance to Phytophthora crown rot were detected on chromosome 4 (QtlPC-C04), 11 (QtlPC-C11) and 14 (QtlPC-C14). Several markers linked to these QTLs are potential targets for MAS against Phytophthora crown rot in C. moschata. The present study reports the first QTLs associated with Phytophthora crown rot resistance in C. moschata.