scholarly journals Genomic features and evolution of the conditionally dispensable chromosome in the tangerine pathotype of Alternaria alternata

2019 ◽  
Vol 20 (10) ◽  
pp. 1425-1438 ◽  
Author(s):  
Mingshuang Wang ◽  
Huilan Fu ◽  
Xing‐Xing Shen ◽  
Ruoxin Ruan ◽  
Antonis Rokas ◽  
...  
Keyword(s):  
Alternaria Alternata ◽  
Genomic Features ◽  
Dispensable Chromosome

scholarly journals Genomic features and evolution of the conditionally dispensable chromosome in the tangerine pathotype of Alternaria alternata

2017 ◽  
Author(s):  
Mingshuang Wang ◽  
Huilan Fu ◽  
Xing-Xing Shen ◽  
Ruoxin Ruan ◽  
Nicholas Pun ◽  
...  
Keyword(s):  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Gene Cluster ◽  
Alternaria Alternata ◽  
Deletion Mutant ◽  
Metabolic Process ◽  
Brown Spot ◽  
P Value ◽  
Dispensable Chromosome ◽  
Cdc Genes

AbstractThe tangerine pathotype of the ascomycete fungus Alternaria alternata is the causal agent of citrus brown spot, which can result in significant losses of both yield and marketability for tangerines and tangerine hybrids worldwide. A conditionally dispensable chromosome (CDC), which harbors the host-selective ACT toxin gene cluster, is required for tangerine pathogenicity of A. alternata. To understand the genetic makeup and evolution of the tangerine pathotype CDC, we analyzed the function and evolution of the CDC genes present in the A. alternata Z7 strain. The 1.84Mb long CDC contains 512 predicted protein-coding genes, which are enriched in functional categories associated with ‘metabolic process’ (132 genes, p-value = 0.00192) including ‘oxidation-reduction process’ (48 genes, p-value = 0.00021) and ‘lipid metabolic process’ (11 genes, p-value = 0.04591). Relatively few of the CDC genes can be classified as CAZymes (13), kinases (3) and transporters (20). Differential transcriptome analysis of H2O2 treatment and control conditions revealed that 29 CDC genes were significantly up-regulated and 14 were significantly down-regulated, suggesting that CDC genes may play a role in coping with oxidative stress. Evolutionary analysis of the 512 CDC proteins showed that their evolutionary conservation tends to be restricted within the genus Alternaria and that the CDC genes evolve faster than genes in the essential chromosomes. Interestingly, phylogenetic analysis suggested that the genes of 13 enzymes and one sugar transporter residing in the CDC were likely horizontally transferred from distantly related species. Among these, one carboxylesterase gene was transferred from bacteria but functionally knocking out this gene revealed no obvious biological role. Another 4 genes might have been transferred from Colletotrichum (Sordariomycetes) and 5 were likely transferred as a physically linked cluster of genes from Cryptococcus (Basidiomycota) or Penicillium (Eurotiomycetes). Functionally knocking out the 5-gene cluster resulted in an 80% decrease in asexual spore production in the deletion mutant. These results provide new insights into the function and evolution of CDC genes in Alternaria.Author SummaryMany fungal phytopathogens harbor conditionally dispensable chromosomes (CDCs). CDCs are variable in size, contain many genes involved in virulence, but their evolution remains obscure. In this study, we investigated the origin of the CDC present in the tangerine pathotype of Alternaria alternata Z7 strain. We found that most of the Z7 CDC proteins are highly conserved within the genus Alternaria but poorly conserved outside the genus. We also discovered that a small number of genes originated via horizontal gene transfer (HGT) from distantly related fungi and bacteria. These horizontally transferred genes include a carboxylesterase gene that was likely acquired from bacteria, a cluster of 4 physically linked genes likely transferred from Colletotrichum, and a cluster of 5 physically linked genes likely transferred from Cryptococcus (Basidiomycota) or Penicillium (Eurotiomycetes). To gain insight into the functions of these transferred genes, we knocked out the bacterial carboxylesterase and the 5-gene cluster. Whereas the carboxylesterase deletion mutant showed no obvious phenotype, the 5-gene cluster mutant showed a dramatically reduced production of asexual spores (conidia). The results of our study suggest that Alternaria CDCs are largely comprised from rapidly evolving native genes; although only a few genes were acquired via horizontal gene transfer, some of them appear to be involved in functions critical to the phytopathogenic lifestyle.

scholarly journals A Conditionally Dispensable Chromosome Controls Host-Specific Pathogenicity in the Fungal Plant Pathogen Alternaria alternata

Genetics ◽  
2002 ◽  
Vol 161 (1) ◽  
pp. 59-70 ◽  
Author(s):  
Rieko Hatta ◽  
Kaoru Ito ◽  
Yoshitsugu Hosaki ◽  
Takayoshi Tanaka ◽  
Aiko Tanaka ◽  
...  
Keyword(s):  
Gene Cluster ◽  
Filamentous Fungus ◽  
Plant Pathogen ◽  
Alternaria Alternata ◽  
Japanese Pear ◽  
Pathogenic Variants ◽  
Dispensable Chromosome ◽  
Fungal Plant Pathogen ◽  
Multiple Copies ◽  
Host Specific Toxins

Abstract The filamentous fungus Alternaria alternata contains seven pathogenic variants (pathotypes), which produce host-specific toxins and cause diseases on different plants. Previously, the gene cluster involved in host-specific AK-toxin biosynthesis of the Japanese pear pathotype was isolated, and four genes, named AKT genes, were identified. The AKT homologs were also found in the strawberry and tangerine pathotypes, which produce AF-toxin and ACT-toxin, respectively. This result is consistent with the fact that the toxins of these pathotypes share a common 9,10-epoxy-8-hydroxy-9-methyl-decatrienoic acid structural moiety. In this study, three of the AKT homologs (AFT1-1, AFTR-1, and AFT3-1) were isolated on a single cosmid clone from strain NAF8 of the strawberry pathotype. In NAF8, all of the AKT homologs were present in multiple copies on a 1.05-Mb chromosome. Transformation-mediated targeting of AFT1-1 and AFT3-1 in NAF8 produced AF-toxin-minus, nonpathogenic mutants. All of the mutants lacked the 1.05-Mb chromosome encoding the AFT genes. This chromosome was not essential for saprophytic growth of this pathogen. Thus, we propose that a conditionally dispensable chromosome controls host-specific pathogenicity of this pathogen.

scholarly journals A Sequence Resource of Autosomes and Additional Chromosomes in the Peach Pathotype of Alternaria alternata

2019 ◽  
Vol 32 (10) ◽  
pp. 1273-1276 ◽  
Author(s):  
Koichiro Ushijima ◽  
Mikihiro Yamamoto
Keyword(s):  
Mitochondrial Genome ◽  
Alternaria Alternata ◽  
Sequence Information ◽  
Saprophytic Fungus ◽  
Dispensable Chromosome ◽  
Novel Host

Alternaria alternata is a generally saprophytic fungus. Its genome consists of 10 autosomes, while some strains have one or two additional chromosomes, called a conditionally dispensable chromosome (CDC). A CDC is not required for reproduction but confers host-specific pathogenicity. We sequenced the genome of the peach pathotype of A. alternata using Nanopore and assembled it into 20 sequences. The 10 largest sequences corresponded to 10 gapless sequences of A. solani autosomes, and 1 sequence was a mitochondrial genome. Nine other sequences may be derived from CDCs because of lack of similarity with autosomes of other Alternaria spp. The sequence information could provide novel insights into genomes of Alternaria spp. and on the biosynthesis of a novel host-specific toxin in the peach pathotype of A. alternata.

Spontaneous loss of a conditionally dispensable chromosome from the Alternaria alternata apple pathotype leads to loss of toxin production and pathogenicity

2001 ◽  
Vol 40 (1) ◽  
pp. 65-72 ◽  
Author(s):  
Linda J. Johnson ◽  
Richard D. Johnson ◽  
Hajime Akamatsu ◽  
Achmadi Salamiah ◽  
Hiroshi Otani ◽  
...  
Keyword(s):  
Alternaria Alternata ◽  
Toxin Production ◽  
Dispensable Chromosome

scholarly journals Functional Analysis of a Multicopy Host-Selective ACT-Toxin Biosynthesis Gene in the Tangerine Pathotype of Alternaria alternata Using RNA Silencing

2008 ◽  
Vol 21 (12) ◽  
pp. 1591-1599 ◽  
Author(s):  
Y. Miyamoto ◽  
A. Masunaka ◽  
T. Tsuge ◽  
M. Yamamoto ◽  
K. Ohtani ◽  
...  
Keyword(s):  
Alternaria Alternata ◽  
Rna Silencing ◽  
Toxin Production ◽  
Brown Spot ◽  
Plasmid Construct ◽  
Dispensable Chromosome ◽  
Alternaria Brown Spot ◽  
Multiple Copies ◽  
Commercially Important ◽  
Serious Disease

Alternaria brown spot, caused by the tangerine pathotype of Alternaria alternata, is a serious disease of commercially important tangerines and their hybrids. The pathogen produces host-selective ACT toxin, and several genes (named ACTT) responsible for ACT-toxin biosynthesis have been identified. These genes have many paralogs, which are clustered on a small, conditionally dispensable chromosome, making it difficult to disrupt entire functional copies of ACTT genes using homologous recombination-mediated gene disruption. To overcome this problem, we attempted to use RNA silencing, which has never been employed in Alternaria spp., to knock down the functional copies of one ACTT gene with a single silencing event. ACTT2, which encodes a putative hydrolase and is present in multiple copies in the genome, was silenced by transforming the fungus with a plasmid construct expressing hairpin ACTT2 RNAs. The ACTT2 RNA-silenced transformant (S-7-24-2) completely lost ACTT2 transcripts and ACT-toxin production as well as pathogenicity. These results indicated that RNA silencing may be a useful technique for studying the role of ACTT genes responsible for host-selective toxin biosynthesis in A. alternata. Further, this technique may be broadly applicable to the analysis of many genes present in multiple copies in fungal genomes that are difficult to analyze using recombination-mediated knockdowns.

DNA transposon fossils present on the conditionally dispensable chromosome controlling AF-toxin biosynthesis and pathogenicity of Alternaria alternata

2006 ◽  
Vol 72 (4) ◽  
pp. 210-219 ◽  
Author(s):  
Rieko Hatta ◽  
Akihisa Shinjo ◽  
Sheila Ruswandi ◽  
Keiji Kitani ◽  
Mikihiro Yamamoto ◽  
...  
Keyword(s):  
Alternaria Alternata ◽  
Dna Transposon ◽  
Dispensable Chromosome

Case Report. Keratomycosis due to Alternaria alternata in a diabetic patient - Fallbericht. Keratomykose durch Alternaria alternata bei einem Diabetiker

Mycoses ◽  
2002 ◽  
Vol 45 (11-12) ◽  
pp. 512-514
Author(s):  
Loranne Vella Zahra ◽  
D. Mallia ◽  
J. Grech Hardie ◽  
A. Bezzina ◽  
T. Fenech
Keyword(s):  
Case Report ◽  
Diabetic Patient ◽  
Alternaria Alternata

Crossreactivity Between Curvularia lunata and Alternaria alternata

2006 ◽  
Vol 18 (06) ◽  
pp. 224-229
Author(s):  
Naveen Arora ◽  
Bhanu Singh ◽  
Ratna Gupta ◽  
Susheela Sridhara ◽  
Raphael Panzani
Keyword(s):  
Alternaria Alternata ◽  
Curvularia Lunata
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