Asset Tag: Rot disease

July 19, 2019  |  

A mobile pathogenicity chromosome in Fusarium oxysporum for infection of multiple cucurbit species.

The genome of Fusarium oxysporum (Fo) consists of a set of eleven ‘core’ chromosomes, shared by most strains and responsible for housekeeping, and one or several accessory chromosomes. We sequenced a strain of Fo f.sp. radicis-cucumerinum (Forc) using PacBio SMRT sequencing. All but one of the core chromosomes were assembled into single contigs, and a chromosome that shows all the hallmarks of a pathogenicity chromosome comprised two contigs. A central part of this chromosome contains all identified candidate effector genes, including homologs of SIX6, SIX9, SIX11 and SIX 13. We show that SIX6 contributes to virulence of Forc. Through horizontal chromosome transfer (HCT) to a non-pathogenic strain, we also show that the accessory chromosome containing the SIX gene homologs is indeed a pathogenicity chromosome for cucurbit infection. Conversely, complete loss of virulence was observed in Forc016 strains that lost this chromosome. We conclude that also a non-wilt-inducing Fo pathogen relies on effector proteins for successful infection and that the Forc pathogenicity chromosome contains all the information necessary for causing root rot of cucurbits. Three out of nine HCT strains investigated have undergone large-scale chromosome alterations, reflecting the remarkable plasticity of Fo genomes.

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July 7, 2019  |  

Evolution of novel wood decay mechanisms in Agaricales revealed by the genome sequences of Fistulina hepatica and Cylindrobasidium torrendii.

Wood decay mechanisms in Agaricomycotina have been traditionally separated in two categories termed white and brown rot. Recently the accuracy of such a dichotomy has been questioned. Here, we present the genome sequences of the white-rot fungus Cylindrobasidium torrendii and the brown-rot fungus Fistulina hepatica both members of Agaricales, combining comparative genomics and wood decay experiments. C. torrendii is closely related to the white-rot root pathogen Armillaria mellea, while F. hepatica is related to Schizophyllum commune, which has been reported to cause white rot. Our results suggest that C. torrendii and S. commune are intermediate between white-rot and brown-rot fungi, but at the same time they show characteristics of decay that resembles soft rot. Both species cause weak wood decay and degrade all wood components but leave the middle lamella intact. Their gene content related to lignin degradation is reduced, similar to brown-rot fungi, but both have maintained a rich array of genes related to carbohydrate degradation, similar to white-rot fungi. These characteristics appear to have evolved from white-rot ancestors with stronger ligninolytic ability. F. hepatica shows characteristics of brown rot both in terms of wood decay genes found in its genome and the decay that it causes. However, genes related to cellulose degradation are still present, which is a plesiomorphic characteristic shared with its white-rot ancestors. Four wood degradation-related genes, homologs of which are frequently lost in brown-rot fungi, show signs of pseudogenization in the genome of F. hepatica. These results suggest that transition toward a brown-rot lifestyle could be an ongoing process in F. hepatica. Our results reinforce the idea that wood decay mechanisms are more diverse than initially thought and that the dichotomous separation of wood decay mechanisms in Agaricomycotina into white rot and brown rot should be revisited. Copyright © 2015 Elsevier Inc. All rights reserved.

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July 7, 2019  |  

Population genomics reveals additive and replacing horizontal gene transfers in the emerging pathogen Dickeya solani.

Dickeya solani is an emerging pathogen that causes soft rot and blackleg diseases in several crops including Solanum tuberosum, but little is known about its genomic diversity and evolution.We combined Illumina and PacBio technologies to complete the genome sequence of D. solani strain 3337 that was used as a reference to compare with 19 other genomes (including that of the type strain IPO2222(T)) which were generated by Illumina technology. This population genomic analysis highlighted an unexpected variability among D. solani isolates since it led to the characterization of two distinct sub-groups within the D. solani species. This approach also revealed different types of variations such as scattered SNP/InDel variations as well as replacing and additive horizontal gene transfers (HGT). Infra-species (between the two D. solani sub-groups) and inter-species (between D. solani and D. dianthicola) replacing HGTs were observed. Finally, this work pointed that genetic and functional variation in the motility trait could contribute to aggressiveness variability in D. solani.This work revealed that D. solani genomic variability may be caused by SNPs/InDels as well as replacing and additive HGT events, including plasmid acquisition; hence the D. solani genomes are more dynamic than that were previously proposed. This work alerts on precautions in molecular diagnosis of this emerging pathogen.

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July 7, 2019  |  

Genome sequence of Pseudomonas chlororaphis strain PA23.

Pseudomonas chlororaphis strain PA23 is a plant-beneficial bacterium that is able to suppress disease caused by the fungal pathogen Sclerotinia sclerotiorum through a process known as biological control. Here we present a 7.1-Mb assembly of the PA23 genome. Copyright © 2014 Loewen et al.

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July 7, 2019  |  

Genome Sequence of Pseudomonas brassicacearum DF41.

Pseudomonas brassicacearum DF41, a Gram-negative soil bacterium, is able to suppress the fungal pathogen Sclerotinia sclerotiorum through a process known as biological control. Here, we present a 6.8-Mb assembly of its genome, which is the second fully assembled genome of a P. brassicacearum strain.

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July 7, 2019  |  

Draft genome sequence of the rhizobacterium Pseudomonas chlororaphis PCL1601, displaying biocontrol against soilborne phytopathogens.

In this study, we present the draft genome sequence of the bacterial strain Pseudomonas chlororaphis PCL1601. This bacterium was isolated from the rhizosphere of healthy avocado trees and displayed antagonistic and biological control activities against different soilborne phytopathogenic fungi and oomycetes. Copyright © 2017 Vida et al.

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July 7, 2019  |  

Genome sequence of the fungal strain 14919 producing 3-hydroxy-3-methylglutaryl–coenzyme A reductase inhibitor FR901512.

Fungal strain 14919 was originally isolated from a soil sample collected at Mt. Kiyosumi, Chiba Prefecture, Japan. It produces FR901512, a potent and strong 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor. The genome sequence of fungal strain 14919 was determined and annotated to improve the productivity of FR901512. Copyright © 2017 Itoh et al.

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July 7, 2019  |  

Comparative genomics of maize ear rot pathogens reveals expansion of carbohydrate-active enzymes and secondary metabolism backbone genes in Stenocarpella maydis.

Stenocarpella maydis is a plant pathogenic fungus that causes Diplodia ear rot, one of the most destructive diseases of maize. To date, little information is available regarding the molecular basis of pathogenesis in this organism, in part due to limited genomic resources. In this study, a 54.8 Mb draft genome assembly of S. maydis was obtained with Illumina and PacBio sequencing technologies, and analyzed. Comparative genomic analyses with the predominant maize ear rot pathogens Aspergillus flavus, Fusarium verticillioides, and Fusarium graminearum revealed an expanded set of carbohydrate-active enzymes for cellulose and hemicellulose degradation in S. maydis. Analyses of predicted genes involved in starch degradation revealed six putative a-amylases, four extracellular and two intracellular, and two putative ?-amylases, one of which appears to have been acquired from bacteria via horizontal transfer. Additionally, 87 backbone genes involved in secondary metabolism were identified, which represents one of the largest known assemblages among Pezizomycotina species. Numerous secondary metabolite gene clusters were identified, including two clusters likely involved in the biosynthesis of diplodiatoxin and chaetoglobosins. The draft genome of S. maydis presented here will serve as a useful resource for molecular genetics, functional genomics, and analyses of population diversity in this organism. Copyright © 2017 British Mycological Society. Published by Elsevier Ltd. All rights reserved.

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July 7, 2019  |  

Draft genomes of the fungal pathogen Phellinus noxius in Hong Kong

The fungal pathogen Phellinus noxius is the underlying cause of brown root rot, a disease with causing tree mortality globally, causing extensive damage in urban areas and crop plants. This disease currently has no cure, and despite the global epidemic, little is known about the pathogenesis and virulence of this pathogen. Using Ion Torrent PGM, Illumina MiSeq and PacBio RSII sequencing platforms with various genome assembly methods, we produced the draft genome sequences of four P. noxius strains isolated from infected trees in Hong Kong to further understand the pathogen and identify the mechanisms behind the aggressive nature and virulence of this fungus. The resulting genomes ranged from 30.8Mb to 31.8Mb in size, and of the four sequences, the YTM97 strain was chosen to produce a high-quality Hong Kong strain genome sequence, resulting in a 31Mb final assembly with 457 scaffolds, an N50 length of 275,889 bp and 96.2% genome completeness. RNA-seq of YTM97 using Illumina HiSeq400 was performed for improved gene prediction. AUGUSTUS and Genemark-ES prediction programs predicted 9,887 protein-coding genes which were annotated using GO and Pfam databases. The encoded carbohydrate active enzymes revealed large numbers of lignolytic enzymes present, comparable to those of other white-rot plant pathogens. In addition, P. noxius also possessed larger numbers of cellulose, xylan and hemicellulose degrading enzymes than other plant pathogens. Searches for virulence genes was also performed using PHI-Base and DFVF databases revealing a host of virulence-related genes and effectors. The combination of non-specific host range, unique carbohydrate active enzyme profile and large amount of putative virulence genes could explain the reasons behind the aggressive nature and increased virulence of this plant pathogen. The draft genome sequences presented here will provide references for strains found in Hong Kong. Together with emerging research, this information could be used for genetic diversity and epidemiology research on a global scale as well as expediting our efforts towards discovering the mechanisms of pathogenicity of this devastating pathogen.

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July 7, 2019  |  

Comparative genomics of early-diverging mushroom-forming fungi provides insights into the origins of lignocellulose decay capabilities.

Evolution of lignocellulose decomposition was one of the most ecologically important innovations in fungi. White-rot fungi in the Agaricomycetes (mushrooms and relatives) are the most effective microorganisms in degrading both cellulose and lignin components of woody plant cell walls (PCW). However, the precise evolutionary origins of lignocellulose decomposition are poorly understood, largely because certain early-diverging clades of Agaricomycetes and its sister group, the Dacrymycetes, have yet to be sampled, or have been undersampled, in comparative genomic studies. Here, we present new genome sequences of ten saprotrophic fungi, including members of the Dacrymycetes and early-diverging clades of Agaricomycetes (Cantharellales, Sebacinales, Auriculariales, and Trechisporales), which we use to refine the origins and evolutionary history of the enzymatic toolkit of lignocellulose decomposition. We reconstructed the origin of ligninolytic enzymes, focusing on class II peroxidases (AA2), as well as enzymes that attack crystalline cellulose. Despite previous reports of white rot appearing as early as the Dacrymycetes, our results suggest that white-rot fungi evolved later in the Agaricomycetes, with the first class II peroxidases reconstructed in the ancestor of the Auriculariales and residual Agaricomycetes. The exemplars of the most ancient clades of Agaricomycetes that we sampled all lack class II peroxidases, and are thus concluded to use a combination of plesiomorphic and derived PCW degrading enzymes that predate the evolution of white rot.

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July 7, 2019  |  

Complete genome anatomy of the emerging potato pathogen Dickeya solani type strain IPO 2222(T).

Several species of the genus Dickeya provoke soft rot and blackleg diseases on a wide range of plants and crops. Dickeya solani has been identified as the causative agent of diseases outbreaks on potato culture in Europe for the last decade. Here, we report the complete genome of the D. solani IPO 2222(T). Using PacBio and Illumina technologies, a unique circular chromosome of 4,919,833 bp was assembled. The G?+?C content reaches 56% and the genomic sequence contains 4,059 predicted proteins. The ANI values calculated for D. solani IPO 2222(T) vs. other available D. solani genomes was over 99.9% indicating a high genetic homogeneity within D. solani species.

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July 7, 2019  |  

Complete genome sequence of Rothia aeria type strain JCM 11412, isolated from air in the Russian space laboratory Mir.

Here, we present the complete genome sequence of Rothia aeria type strain JCM 11412, isolated from air in the Russian space laboratory Mir. Recently, there has been an increasing number of reports on infections caused by R. aeria The genomic information will enable researchers to identify the pathogenicity of this organism. Copyright © 2016 Nambu et al.

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July 7, 2019  |  

Draft genome sequence of the phytopathogenic fungus Ganoderma boninense, the causal agent of basal stem rot disease on oil palm.

Ganoderma boninense is the dominant fungal pathogen of basal stem rot (BSR) disease on Elaeis guineensis We sequenced the nuclear genome of mycelia using both Illumina and Pacific Biosciences platforms for assembly of scaffolds. The draft genome comprised 79.24?Mb, 495 scaffolds, and 26,226 predicted coding sequences. Copyright © 2018 Utomo et al.

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