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1.
Phytopathology ; 114(1): 119-125, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-37531627

RESUMEN

Macrophomina phaseolina is a plant pathogenic fungus that is frequently described as having a broad host range encompassing more than 500 species. We noticed that citations provided in support of this statement do not actually demonstrate such a broad host range. To elucidate the true documented host range of this fungus, we initiated a literature meta-analysis of 894 publications on M. phaseolina since 1913. We discovered that the first host range summaries did not require Koch's postulates or other experimental demonstrations of pathogenicity. Most of the available early host claims were based on tenuous associations between the fungus and symptoms, sometimes without reporting isolation or morphological examination in vitro. These statements apparently led to a pattern of increasingly exaggerated host range claims, without support from a primary reference, until the claim that M. phaseolina has 500 hosts became common in the early 2000s. At present, the scientific community typically requires Koch's postulates to characterize pathogenicity on a new host. Among all the available literature, we only found primary experimental evidence for M. phaseolina's pathogenicity on 97 hosts; 74 hosts confirmed by Koch's postulates and 23 hosts with all steps from Koch's postulates completed except for recovery of the pathogen from symptomatic tissues. This study demonstrates how scientific concepts can change over time and necessitate changes to historic axioms. We propose that the hyperbole surrounding the host range of M. phaseolina has obscured an accurate depiction of its biology.


Asunto(s)
Ascomicetos , Enfermedades de las Plantas , Enfermedades de las Plantas/microbiología , Ascomicetos/genética , Especificidad del Huésped
2.
Plant Dis ; 2023 May 03.
Artículo en Inglés | MEDLINE | ID: mdl-37134247

RESUMEN

In California, Fusarium wilt of strawberry is widespread and causes significant yield losses. Resistant cultivars with the FW1 gene were protected against Fusarium wilt because all strains of Fusarium oxysporum f. sp. fragariae (Fof) in California were race 1 (i.e., avirulent to FW1-resistant cultivars) (Henry et al. 2017; Pincot, et al. 2018; Henry et al. 2021). In the fall of 2022, severe wilt disease was observed in an organic, summer-planted strawberry field in Oxnard, California. Fusarium wilt symptoms were common and included wilted foliage, deformed and highly chlorotic leaflets, and crown discoloration. The field was planted with Portola, a cultivar with the FW1 gene that is resistant to Fof race 1 (Pincot et al. 2018; Henry et al. 2021). Two samples, each consisting of four plants, were collected from two different locations within the field. Crown extracts from each sample were tested for Fof, Macrophomina phaseolina, Verticillium dahliae, and Phytophthora spp. by recombinase polymerase amplification (RPA) (Steele et al. 2022). Petioles were surface sterilized in 1% sodium hypochlorite for 2 minutes and plated on Komada's medium to select for Fusarium spp. (Henry et al. 2021; Komada, 1975). The RPA results were positive for M. phaseolina in one sample and negative for all four pathogens in the other sample. Salmon-colored, fluffy mycelia grew profusely from petioles of both samples. Colony morphology and non-septate, ellipsoidal microconidia (6.0-13 µm × 2.8-4.0 µm) borne on monophialides resembled F. oxysporum. Single hyphal tip isolation of fourteen cultures (P1-P14) was done to purify single genotypes. None of these pure cultures amplified with Fof-specific qPCR (Burkhardt et al. 2019), confirming the negative result obtained with RPA. Translation elongation factor 1-alpha (EF1α) was amplified using EF1/EF2 primers (O'Donnell et al. 1998) from three isolates. Amplicons were sequenced (GenBank OQ183721) and found through BLAST search to have 100% identity with an isolate of Fusarium oxysporum f. sp. melongenae (GenBank FJ985297). There was at least one nucleotide difference when compared to all known strains of Fof race 1 (Henry et al. 2021). Five isolates (P2, P3, P6, P12, and P13) and an Fof race 1 control isolate (GL1315) were tested for pathogenicity on Fronteras (FW1) and Monterey (fw1; susceptible to race 1). Five plants per isolate × cultivar combination were inoculated by dipping roots in 5 × 106 conidia per mL of 0.1% water agar, or in sterile 0.1% water agar for the negative control, and grown as described by Jenner and Henry (2022). After six weeks, all non-inoculated control plants remained healthy while plants of both cultivars inoculated with the five isolates were severely wilted. Petiole assays yielded colonies identical in appearance to the inoculated isolates. For Fof race 1-inoculated plants, wilt symptoms were observed in Monterey but not in Fronteras. This experiment was repeated with P2, P3, P12, and P13 on another FW1 cultivar, San Andreas, and the same results were observed. To our knowledge, this is the first report of F. oxysporum f. sp. fragariae race 2 in California. Losses to Fusarium wilt are likely to increase until genetic resistance to this strain of Fof race 2 is deployed in commercially viable cultivars.

4.
J Exp Bot ; 73(2): 487-497, 2022 01 13.
Artículo en Inglés | MEDLINE | ID: mdl-34727164

RESUMEN

Signaling via volatile organic compounds (VOCs) has historically been studied mostly by entomologists; however, botanists and mycologists are increasingly aware of the physiological potential of chemical communication in the gas phase. Most research to date focuses on the observed effects of VOCs on different organisms such as differential growth or metabolite production. However, with the increased interest in volatile signaling, more researchers are investigating the molecular mechanisms for these effects. Eight-carbon VOCs are among the most prevalent and best-studied fungal volatiles. Therefore, this review emphasizes examples of eight-carbon VOCs affecting plants and fungi. These compounds display different effects that include growth suppression in both plants and fungi, induction of defensive behaviors such as accumulation of mycotoxins, phytohormone signaling cascades, and the inhibition of spore and seed germination. Application of '-omics' and other next-generation sequencing techniques is poised to decipher the mechanistic basis of volatiles in plant-fungal communication.


Asunto(s)
Micotoxinas , Compuestos Orgánicos Volátiles , Carbono , Hongos , Plantas
5.
J Fungi (Basel) ; 7(9)2021 Sep 09.
Artículo en Inglés | MEDLINE | ID: mdl-34575780

RESUMEN

Blue mold of apple is caused by several different Penicillium species, among which P. expansum and P. solitum are the most frequently isolated. P. expansum is the most aggressive species, and P. solitum is very weak when infecting apple fruit during storage. In this study, we report complete genomic analyses of three different Penicillium species: P. expansum R21 and P. crustosum NJ1, isolated from stored apple fruit; and P. maximae 113, isolated in 2013 from a flooded home in New Jersey, USA, in the aftermath of Hurricane Sandy. Patulin and citrinin gene cluster analyses explained the lack of patulin production in NJ1 compared to R21 and lack of citrinin production in all three strains. A Drosophila bioassay demonstrated that volatiles emitted by P. solitum SA and P. polonicum RS1 were more toxic than those from P. expansum and P. crustosum strains (R27, R11, R21, G10, and R19). The toxicity was hypothesized to be related to production of eight-carbon oxylipins. Putative lipoxygenase genes were identified in P. expansum and P. maximae strains, but not in P. crustosum. Our data will provide a better understanding of Penicillium spp. complex secondary metabolic capabilities, especially concerning the genetic bases of mycotoxins and toxic VOCs.

6.
J Ind Microbiol Biotechnol ; 48(9-10)2021 Dec 23.
Artículo en Inglés | MEDLINE | ID: mdl-34415032

RESUMEN

White-nose syndrome is an emergent wildlife disease that has killed millions of North American bats. It is caused by Pseudogymnoascus destructans, a cold-loving, invasive fungal pathogen that grows on bat tissues and disrupts normal hibernation patterns. Previous work identified trans-2-hexenal as a fungistatic volatile compound that potentially could be used as a fumigant against P. destructans in bat hibernacula. To determine the physiological responses of the fungus to trans-2-hexenal exposure, we characterized the P. destructans transcriptome in the presence and absence of trans-2-hexenal. Specifically, we analyzed the effects of sublethal concentrations (5 µmol/L, 10 µmol/L, and 20 µmol/L) of gas-phase trans-2-hexenal of the fungus grown in liquid culture. Among the three treatments, a total of 407 unique differentially expressed genes (DEGs) were identified, of which 74 were commonly affected across all three treatments, with 44 upregulated and 30 downregulated. Downregulated DEGs included several probable virulence genes including those coding for a high-affinity iron permease, a superoxide dismutase, and two protein-degrading enzymes. There was an accompanying upregulation of an ion homeostasis gene, as well as several genes involved in transcription, translation, and other essential cellular processes. These data provide insights into the mechanisms of action of trans-2-hexenal as an anti-fungal fumigant that is active at cold temperatures and will guide future studies on the molecular mechanisms by which six carbon volatiles inhibit growth of P. destructans and other pathogenic fungi.


Asunto(s)
Ascomicetos , Quirópteros , Aldehídos , Animales , Ascomicetos/genética , Virulencia
7.
BMC Microbiol ; 20(1): 342, 2020 11 11.
Artículo en Inglés | MEDLINE | ID: mdl-33176679

RESUMEN

BACKGROUND: Members of the genus Aspergillus display a variety of lifestyles, ranging from saprobic to pathogenic on plants and/or animals. Increased genome sequencing of economically important members of the genus permits effective use of "-omics" comparisons between closely related species and strains to identify candidate genes that may contribute to phenotypes of interest, especially relating to pathogenicity. Protein-coding genes were predicted from 216 genomes of 12 Aspergillus species, and the frequencies of various structural aspects (exon count and length, intron count and length, GC content, and codon usage) and functional annotations (InterPro, Gene Ontology, and Kyoto Encyclopedia of Genes and Genomes terms) were compared. RESULTS: Using principal component analyses, the three sets of functional annotations for each strain were clustered by species. The species clusters appeared to separate by pathogenicity on plants along the first dimensions, which accounted for over 20% of the variance. More annotations for genes encoding pectinases and secondary metabolite biosynthetic enzymes were assigned to phytopathogenic strains from species such as Aspergillus flavus. In contrast, Aspergillus fumigatus strains, which are pathogenic to animals but not plants, were assigned relatively more terms related to phosphate transferases, and carbohydrate and amino-sugar metabolism. Analyses of publicly available RNA-Seq data indicated that one A. fumigatus protein among 17 amino-sugar processing candidates, a hexokinase, was up-regulated during co-culturing with human immune system cells. CONCLUSION: Genes encoding hexokinases and other proteins of interest may be subject to future manipulations to further refine understanding of Aspergillus pathogenicity factors.


Asunto(s)
Aspergillus/genética , Factores de Virulencia/genética , Animales , Aspergillus/clasificación , Aspergillus/patogenicidad , Genes Fúngicos/genética , Genoma Fúngico/genética , Hexoquinasa/genética , Humanos , Anotación de Secuencia Molecular , Enfermedades de las Plantas/microbiología
8.
J Fungi (Basel) ; 5(2)2019 Jun 20.
Artículo en Inglés | MEDLINE | ID: mdl-31226781

RESUMEN

Biocontrol of the mycotoxin aflatoxin utilizes non-aflatoxigenic strains of Aspergillus flavus, which have variable success rates as biocontrol agents. One non-aflatoxigenic strain, NRRL 35739, is a notably poor biocontrol agent. Its growth in artificial cultures and on peanut kernels was found to be slower than that of two aflatoxigenic strains, and NRRL 35739 exhibited less sporulation when grown on peanuts. The non-aflatoxigenic strain did not greatly prevent aflatoxin accumulation. Comparison of the transcriptomes of aflatoxigenic and non-aflatoxigenic A. flavus strains AF36, AF70, NRRL 3357, NRRL 35739, and WRRL 1519 indicated that strain NRRL 35739 had increased relative expression of six heat shock and stress response proteins, with the genes having relative read counts in NRRL 35739 that were 25 to 410 times more than in the other four strains. These preliminary findings tracked with current thought that aflatoxin biocontrol efficacy is related to the ability of a non-aflatoxigenic strain to out-compete aflatoxigenic ones. The slower growth of NRRL 35739 might be due to lower stress tolerance or overexpression of stress response(s). Further study of NRRL 35739 is needed to refine our understanding of the genetic basis of competitiveness among A. flavus strains.

9.
Mycotoxin Res ; 35(4): 329-340, 2019 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-31025195

RESUMEN

1-Octen-3-ol is one of the most abundant volatile compounds associated with fungi and functions as a germination and growth inhibitor in several species. By investigating its effect on the biosynthesis of patulin, a mycotoxin made by Penicillium expansum, it was found that a sub-inhibitory level of volatile 1-octen-3-ol increased accumulation of patulin on a medium that normally suppresses the mycotoxin. Transcriptomic sequencing and comparisons of control and treated P. expansum grown on potato dextrose agar (PDA; patulin permissive) or secondary medium agar (SMA; patulin suppressive) revealed that the expression of gox2, a gene encoding a glucose oxidase, was significantly affected, decreasing 10-fold on PDA and increasing 85-fold on SMA. Thirty other genes, mostly involved in transmembrane transport, oxidation-reduction, and carbohydrate metabolism were also differently expressed on the two media. Transcription factors previously found to be involved in regulation of patulin biosynthesis were not significantly affected despite 1-octen-3-ol increasing patulin production on SMA. Further study is needed to determine the relationship between the upregulation of patulin biosynthesis genes and gox2 on SMA, and to identify the molecular mechanism by which 1-octen-3-ol induced this effect.


Asunto(s)
Medios de Cultivo/química , Octanoles/farmacología , Patulina/biosíntesis , Penicillium/efectos de los fármacos , Penicillium/metabolismo , Vías Biosintéticas , Perfilación de la Expresión Génica , Glucosa Oxidasa/genética , Penicillium/genética , Volatilización
10.
J Ind Microbiol Biotechnol ; 46(7): 977-991, 2019 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-30923972

RESUMEN

Inhibition of spore germination offers an attractive and effective target for controlling fungal species involved in food spoilage. Mushroom alcohol (1-octen-3-ol) functions as a natural self-inhibitor of spore germination for many fungi and, therefore, provides a useful tool for probing the molecular events controlling the early stages of fungal growth. In Penicillium spp., the R and S enantiomers of 1-octen-3-ol delayed spore germination and sporulation in four species of Penicillium involved in soils of fruit and grains, but to different degrees. Because of its well-annotated genome, we used Penicillium chrysogenum to perform a comprehensive comparative transcriptomic analysis of cultures treated with the two enantiomers. Altogether, about 80% of the high-quality reads could be mapped to 11,396 genes in the reference genome. The top three active pathways were metabolic (978 transcripts), biosynthesis of secondary metabolites (420 transcripts), and microbial metabolism in diverse environments (318 transcripts). When compared to the control, treatment with (R)-(-)-1-octen-3-ol affected the transcription levels of 91 genes, while (S)-(+)-1-octen-3-ol affected only 41 genes. Most of the affected transcripts were annotated and predicted to be involved in transport, establishment of localization, and transmembrane transport. Alternative splicing and SNPs' analyses indicated that, compared to the control, the R enantiomer had greater effects on the gene expression pattern of Penicillium chrysogenum than the S enantiomer. A qRT-PCR analysis of 28 randomly selected differentially expressed genes confirmed the transcriptome data. The transcriptomic data have been deposited in NCBI SRA under the accession number SRX1065226.


Asunto(s)
Octanoles/metabolismo , Penicillium chrysogenum/metabolismo , Expresión Génica , Octanoles/química , Penicillium/efectos de los fármacos , Penicillium chrysogenum/genética , Estereoisomerismo , Transcriptoma
11.
Chin J Nat Med ; 17(2): 131-144, 2019 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-30797419

RESUMEN

Anemone flaccida Fr. Schmidt is a perennial medicinal herb that contains pentacyclic triterpenoid saponins as the major bioactive constituents. In China, the rhizomes are used as treatments for a variety of ailments including arthritis. However, yields of the saponins are low, and little is known about the plant's genetic background or phytohormonal responsiveness. Using one-quarter of the 454 pyrosequencing information from the Roche GS FLX Titanium platform, we performed a transcriptomic analysis to identify 157 genes putatively encoding 26 enzymes involved in the synthesis of the bioactive compounds. It was revealed that there are two biosynthetic pathways of triterpene saponins in A. flaccida. One pathway depends on ß-amyrin synthase and is similar to that found in other plants. The second, subsidiary ("backburner") pathway is catalyzed by camelliol C synthase and yields ß-amyrin as minor byproduct. Both pathways used cytochrome P450-dependent monooxygenases (CYPs) and family 1 uridine diphosphate glycosyltransferases (UGTs) to modify the triterpenoid backbone. The expression of CYPs and UGTs were quite different in roots treated with the phytohormones methyl jasmonate, salicylic acid and indole-3-acetic acid. This study provides the first large-scale transcriptional dataset for the biosynthetic pathways of triterpene saponins and their phytohormonal responsiveness in the genus Anemone.


Asunto(s)
Anemone/genética , Vías Biosintéticas/efectos de los fármacos , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Reguladores del Crecimiento de las Plantas/farmacología , Saponinas/metabolismo , Triterpenos/metabolismo , Anemone/efectos de los fármacos , Anemone/metabolismo , Vías Biosintéticas/genética , Sistema Enzimático del Citocromo P-450/genética , Sistema Enzimático del Citocromo P-450/metabolismo , Perfilación de la Expresión Génica , Glicosiltransferasas/genética , Glicosiltransferasas/metabolismo , Ácido Oleanólico/análogos & derivados , Ácido Oleanólico/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Medicinales , Rizoma/efectos de los fármacos , Rizoma/genética , Rizoma/metabolismo
12.
Saudi J Biol Sci ; 25(8): 1577-1584, 2018 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-30581320

RESUMEN

Rice ragged stunt virus (RRSV) is a very important virus that infects rice and causes serious yield losses in Asian countries and other major rice planting areas. Thus, it is urgent to establish an efficient and practical approach for identification and diagnosis in the field. Our results indicated that reverse transcription loop-mediated isothermal amplification (RT-LAMP) reactions are more efficient and sensitive than RT-PCR for RRSV detection. The optimal LAMP conditions were as follows: 0.4-1.2 µM internal primers, 0.2-0.25 µM external primers, 0.8 µM loop primers, and incubation at 62 °C or 63 °C for 30 min. Furthermore, the RT-LAMP primers specifically targeted RRSV virus and resulted in typical waterfall-like bands by gel electrophoresis and sigmoidal amplification curves. The primers could not be used to amplify other common plant viruses including Papaya ringspot virus (PRSV), Rice yellow stunt virus (RYSV), Sorghum mosaic virus (SrMV), Cactus virus X (CVX), Melon yellow spot virus (MYSV) and Southern rice black-streaked dwarf virus (SRBSDV). Ten-fold serial dilutions of RRSV cDNA indicated that RT-LAMP is much faster and at least ten times more sensitive than RT-PCR in detecting the virus. The waterfall-like product bands could be observed within one hour. In the field study, about 77% samples were identified as RRSV. RT-LAMP has many benefits over RT-PCR such as low cost and high accuracy, sensitivity, and specificity. This technology meets the requirements for rapid diagnosis of plant virus diseases in the field to best guide management practices for growers.

13.
Int J Mol Sci ; 19(10)2018 Oct 11.
Artículo en Inglés | MEDLINE | ID: mdl-30314311

RESUMEN

Drought stress is a global problem, and the lack of water is a key factor that leads to agricultural shortages. MicroRNAs play a crucial role in the plant drought stress response; however, the microRNAs and their targets involved in drought response have not been well elucidated. In the present study, we used Illumina platform (https://www.illumina.com/) and combined data from miRNA, RNA, and degradome sequencing to explore the drought- and organ-specific miRNAs in orchardgrass (Dactylis glomerata L.) leaf and root. We aimed to find potential miRNA⁻mRNA regulation patterns responding to drought conditions. In total, 519 (486 conserved and 33 novel) miRNAs were identified, of which, 41 miRNAs had significant differential expression among the comparisons (p < 0.05). We also identified 55,366 unigenes by RNA-Seq, where 12,535 unigenes were differently expressed. Finally, our degradome analysis revealed that 5950 transcripts were targeted by 487 miRNAs. A correlation analysis identified that miRNA ata-miR164c-3p and its target heat shock protein family A (HSP70) member 5 gene comp59407_c0 (BIPE3) may be essential in organ-specific plant drought stress response and/or adaptation in orchardgrass. Additionally, Gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) analyses found that "antigen processing and presentation" was the most enriched downregulated pathway in adaptation to drought conditions. Taken together, we explored the genes and miRNAs that may be involved in drought adaptation of orchardgrass and identified how they may be regulated. These results serve as a valuable genetic resource for future studies focusing on how plants adapted to drought conditions.


Asunto(s)
Dactylis/fisiología , Sequías , Regulación de la Expresión Génica de las Plantas , MicroARNs/genética , Hojas de la Planta/fisiología , Raíces de Plantas/fisiología , ARN de Planta/genética , Estrés Fisiológico , Adaptación Biológica , Biología Computacional/métodos , Perfilación de la Expresión Génica , Ontología de Genes , Secuenciación de Nucleótidos de Alto Rendimiento , Interferencia de ARN , Estabilidad del ARN , ARN Mensajero , Transcriptoma
14.
J Insect Sci ; 18(5)2018 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-30346622

RESUMEN

Glutathione-S-transferases (GST) comprise a multifunctional protein superfamily, which plays important roles as detoxifiers and antioxidants in insects. The GST in Asian corn borer has not been previously characterized. In this study, we cloned, characterized, and expressed the complete GST genes from the midgut of Asian corn borer. Furthermore, we designed htL4440-OfGST vector to exploit this gene for RNA interference (RNAi) strategy to control this pest. A complete GST cDNA sequence in Asian corn borer was obtained by reverse transcription polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends technology. The gene was 887bp in length and contained a 705bp open reading frame and 5' UTR and 3' UTR lengths of 89 and 93bp, respectively. The putative sequence encoded a putative 234 amino acid residue peptide and had a predicted molecular weight of ~26kDa. The GST protein of Asian corn borer is hydrophilic and may have a 30 amino acid signal peptide with a cleavage site between L30 and K31. A recombination vector pET28a-OfGST was constructed for purification and antibody preparation. Western blotting analysis showed that this protein reached the maximum expression level around 24 h in Asian corn borer larvae fed the plant toxin 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one. A second vector, htL4440-OfGST, was constructed to generate the dsRNA of the GST gene. A larval feeding bioassay showed that the expressed dsRNA significantly reduced the detoxification ability of Asian corn borer larvae and increased mortality rate up to 54%. Our data indicated that GST plays very important roles in detoxifying in Asian corn borer and can be used as an RNAi method to control this pest in the field.


Asunto(s)
Glutatión Transferasa/genética , Control de Insectos/métodos , Proteínas de Insectos/genética , Mariposas Nocturnas/genética , Interferencia de ARN , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Glutatión Transferasa/química , Glutatión Transferasa/metabolismo , Proteínas de Insectos/química , Proteínas de Insectos/metabolismo , Larva/genética , Larva/crecimiento & desarrollo , Larva/metabolismo , Mariposas Nocturnas/crecimiento & desarrollo , Mariposas Nocturnas/metabolismo , Filogenia , ARN Bicatenario/genética
15.
Mol Genet Genomics ; 293(6): 1507-1522, 2018 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-30099586

RESUMEN

Aflatoxins are toxic secondary metabolites produced by members of the genus Aspergillus, most notably A. flavus. Non-aflatoxigenic strains of A. flavus are commonly used for biocontrol of the aflatoxigenic strains to reduce aflatoxins in corn, cotton, peanuts and tree nuts. However, genomic differences between aflatoxigenic strains and non-aflatoxigenic strains have not been reported in detail, though such differences may further elucidate the evolutionary histories of certain biocontrol strains and help guide development of other useful strains. We recently reported the genome and transcriptome sequencing of A. flavus WRRL 1519, a strain isolated from almond that does not produce aflatoxins or cyclopiazonic acid due to deletions in the biosynthetic gene clusters. Continued bioinformatics analyses focused on comparing strain WRRL 1519 to the aflatoxigenic strain NRRL 3357. The genome assembly of strain WRRL 1519 was improved by anchoring 84 of the 127 scaffolds to the putative nuclear chromosomes of strain NRRL 3357. The five largest areas of extrachromosomal mismatches observed between WRRL 1519 and NRRL 3357 were not similar to any of the mismatches that were observed with pairwise comparisons of NRRL 3357 to other non-aflatoxigenic strains NRRL 21882, NRRL 30797 or NRRL 18543. Comparisons of predicted secondary metabolite gene clusters uncovered two other biosynthetic gene clusters in which strain WRRL 1519 had large deletions compared to the homologous clusters in NRRL 3357. Additionally, there was a marked overrepresentation of repetitive sequences in WRRL 1519 compared to other inspected A. flavus strains. This is the first report of detection of a large number of putative retrotransposons in any A. flavus strain, initially suggesting that retrotransposons may contribute to the natural occurrence of genetic variation and biocontrol strains. However, the transposons may not be significantly associated with the chromosomal differences. Future experimentation and continued bioinformatics analyses will potentially illuminate causes of the differences and may reveal whether transposon activity in A. flavus can lead to random natural occurrences of non-aflatoxigenic strains.


Asunto(s)
Aspergillus flavus/genética , Agentes de Control Biológico , Cromosomas Fúngicos/genética , Elementos Transponibles de ADN/genética , Variación Genética , Mapeo Cromosómico , Variaciones en el Número de Copia de ADN , Evolución Molecular , Dosificación de Gen , Especificidad de la Especie
16.
Mycologia ; 110(3): 482-493, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-29969379

RESUMEN

Aflatoxins are toxic secondary metabolites produced by Aspergillus flavus and a few other closely related species of Aspergillus. These highly toxigenic and carcinogenic mycotoxins contaminate global food and feed supplies, posing widespread health risks to humans and domestic animals. Field application of nonaflatoxigenic strains of A. flavus to compete against aflatoxigenic strains has emerged as one of the best management practices for reducing aflatoxins contamination, yielding successful commercial products for corn, cotton seed, and peanuts. In this study, we sequenced the genome and transcriptome of atoxigenic (does not produce aflatoxin or cyclopiazonic acid) A. flavus strain WRRL 1519 isolated from a tree nut orchard to define the genetic characteristics of the strain in relation to aflatoxigenic and other nonaflatoxigenic A. flavus strains. WRRL 1519 strain was similar to other strains in size (38.0 Mb), GC content (47.2%), number of predicted secondary metabolite gene clusters (46), and number of putative proteins (12 121). About 87.4% of the predicted proteome had high shared identity with protein sequences derived from other A. flavus genomes. However, the atoxigenic A. flavus strain WRRL 1519 had deletions, or low shared identity, for many genes in the clusters required for aflatoxins and cyclopiazonic acid (CPA) synthesis. Over half of the aflatoxin synthesis gene cluster was missing, and none of the components of the CPA gene cluster were identified with high sequence similarity. Importantly, the strain appeared to maintain functional sequences of several genes thought to be required for high infectivity. Since the ability to grow on target crop is an important attribute for a successful biocontrol agent, these results indicate that the nonaflatoxigenic A. flavus strain WRRL 1519 would be a good candidate as a biocontrol agent for reducing aflatoxin and CPA accumulation in high-value nut crops.


Asunto(s)
Aspergillus flavus/genética , Genoma Fúngico/genética , Aflatoxinas/análisis , Aflatoxinas/genética , Aspergillus flavus/metabolismo , Composición de Base , Secuencia de Bases , Agentes de Control Biológico , Tamaño del Genoma , Indoles/análisis , Familia de Multigenes/genética , Nueces/microbiología , Proteómica , Metabolismo Secundario/genética , Eliminación de Secuencia , Transcriptoma
17.
Genome Announc ; 5(7)2017 Feb 16.
Artículo en Inglés | MEDLINE | ID: mdl-28209811

RESUMEN

Blue mold is the vernacular name of a common postharvest disease of stored apples, pears, and quince that is caused by several common species of Penicillium This study reports the draft genome sequence of Penicillium expansum strain R21, which was isolated from a red delicious apple in 2011 in Pennsylvania.

18.
J Fungi (Basel) ; 3(1)2017 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-29371531

RESUMEN

Penicillium is a large genus of common molds with over 400 described species; however, identification of individual species is difficult, including for those species that cause postharvest rots. In this study, blue rot fungi from stored apples and pears were isolated from a variety of hosts, locations, and years. Based on morphological and cultural characteristics and partial amplification of the ß-tubulin locus, the isolates were provisionally identified as several different species of Penicillium. These isolates were investigated further using a suite of molecular DNA markers and compared to sequences of the ex-type for cognate species in GenBank, and were identified as P. expansum (3 isolates), P. solitum (3 isolates), P. carneum (1 isolate), and P. paneum (1 isolate). Three of the markers we used (ITS, internal transcribed spacer rDNA sequence; benA, ß-tubulin; CaM, calmodulin) were suitable for distinguishing most of our isolates from one another at the species level. In contrast, we were unable to amplify RPB2 sequences from four of the isolates. Comparison of our sequences with cognate sequences in GenBank from isolates with the same species names did not always give coherent data, reinforcing earlier studies that have shown large intraspecific variability in many Penicillium species, as well as possible errors in some sequence data deposited in GenBank.

19.
Genome Announc ; 4(6)2016 Nov 23.
Artículo en Inglés | MEDLINE | ID: mdl-27881534

RESUMEN

Penicillium sclerotiorum is a distinctive species within the genus Penicillium that usually produces vivid orange to red colonies, sometimes with colorful sclerotia. Here, we report the first draft genome sequence of P. sclerotiorum strain 113, isolated in 2013 in the aftermath of Hurricane Sandy from a flooded home in New Jersey.

20.
Genome Announc ; 4(6)2016 Nov 23.
Artículo en Inglés | MEDLINE | ID: mdl-27881535

RESUMEN

Penicillium solitum is one of the most prevalent species causing postharvest decay of pomaceous fruits during storage. Here, we report the draft genome of P. solitum strain NJ1, received as a transfer of a strain originally identified as P. griseofulvum by classical means.

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