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

The 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 worldwide. A conditionally dispensable chromosome (CDC), which harbours the host‐selective ACT toxin g...

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Autores principales: Wang, Mingshuang, Fu, Huilan, Shen, Xing‐Xing, Ruan, Ruoxin, Rokas, Antonis, Li, Hongye
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6792136/
https://www.ncbi.nlm.nih.gov/pubmed/31297970
http://dx.doi.org/10.1111/mpp.12848
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author Wang, Mingshuang
Fu, Huilan
Shen, Xing‐Xing
Ruan, Ruoxin
Rokas, Antonis
Li, Hongye
author_facet Wang, Mingshuang
Fu, Huilan
Shen, Xing‐Xing
Ruan, Ruoxin
Rokas, Antonis
Li, Hongye
author_sort Wang, Mingshuang
collection PubMed
description The 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 worldwide. A conditionally dispensable chromosome (CDC), which harbours 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 isolated and sequenced the CDCs of the A. alternata Z7 strain and analysed the function and evolution of their genes. The A. alternata Z7 strain has two CDCs (~1.1 and ~0.8 Mb, respectively), and the longer Z7 CDC contains all but one contig of the shorter one. Z7 CDCs contain 254 predicted protein‐coding genes, which are enriched in functional categories associated with ‘metabolic process’ (55 genes, P = 0.037). Relatively few of the CDC genes can be classified as carbohydrate‐active enzymes (CAZymes) (4) and transporters (19) and none as kinases. Evolutionary analysis of the 254 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, likely due to fewer selective constraints. Interestingly, phylogenetic analysis suggested that four of the 25 genes responsible for the ACT toxin production were likely transferred from Colletotrichum (Sordariomycetes). Functional experiments showed that two of them are essential for the virulence of the tangerine pathotype of A. alternata. These results provide new insights into the function and evolution of CDC genes in Alternaria.
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spelling pubmed-67921362019-10-21 Genomic features and evolution of the conditionally dispensable chromosome in the tangerine pathotype of Alternaria alternata Wang, Mingshuang Fu, Huilan Shen, Xing‐Xing Ruan, Ruoxin Rokas, Antonis Li, Hongye Mol Plant Pathol Original Articles The 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 worldwide. A conditionally dispensable chromosome (CDC), which harbours 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 isolated and sequenced the CDCs of the A. alternata Z7 strain and analysed the function and evolution of their genes. The A. alternata Z7 strain has two CDCs (~1.1 and ~0.8 Mb, respectively), and the longer Z7 CDC contains all but one contig of the shorter one. Z7 CDCs contain 254 predicted protein‐coding genes, which are enriched in functional categories associated with ‘metabolic process’ (55 genes, P = 0.037). Relatively few of the CDC genes can be classified as carbohydrate‐active enzymes (CAZymes) (4) and transporters (19) and none as kinases. Evolutionary analysis of the 254 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, likely due to fewer selective constraints. Interestingly, phylogenetic analysis suggested that four of the 25 genes responsible for the ACT toxin production were likely transferred from Colletotrichum (Sordariomycetes). Functional experiments showed that two of them are essential for the virulence of the tangerine pathotype of A. alternata. These results provide new insights into the function and evolution of CDC genes in Alternaria. John Wiley and Sons Inc. 2019-07-11 /pmc/articles/PMC6792136/ /pubmed/31297970 http://dx.doi.org/10.1111/mpp.12848 Text en © 2019 The Authors. Molecular Plant Pathology published by British Society for Plant Pathology and John Wiley & Sons Ltd This is an open access article under the terms of the http://creativecommons.org/licenses/by-nc/4.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
spellingShingle Original Articles
Wang, Mingshuang
Fu, Huilan
Shen, Xing‐Xing
Ruan, Ruoxin
Rokas, Antonis
Li, Hongye
Genomic features and evolution of the conditionally dispensable chromosome in the tangerine pathotype of Alternaria alternata
title Genomic features and evolution of the conditionally dispensable chromosome in the tangerine pathotype of Alternaria alternata
title_full Genomic features and evolution of the conditionally dispensable chromosome in the tangerine pathotype of Alternaria alternata
title_fullStr Genomic features and evolution of the conditionally dispensable chromosome in the tangerine pathotype of Alternaria alternata
title_full_unstemmed Genomic features and evolution of the conditionally dispensable chromosome in the tangerine pathotype of Alternaria alternata
title_short Genomic features and evolution of the conditionally dispensable chromosome in the tangerine pathotype of Alternaria alternata
title_sort genomic features and evolution of the conditionally dispensable chromosome in the tangerine pathotype of alternaria alternata
topic Original Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6792136/
https://www.ncbi.nlm.nih.gov/pubmed/31297970
http://dx.doi.org/10.1111/mpp.12848
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