A Conditionally Dispensable Chromosome Controls Host-Specific Pathogenicity in the Fungal Plant Pathogen <i>Alternaria alternata</i>

Hatta, Rieko; Ito, Kaoru; Hosaki, Yoshitsugu; Tanaka, Takayoshi; Tanaka, Aiko; Yamamoto, Mikihiro; Akimitsu, Kazuya; Tsuge, Takashi

doi:10.1093/genetics/161.1.59

Cited by 198 publications

(31 citation statements)

References 56 publications

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“…The second model (White, 1973) proposed that B chromosomes may be maintained in the population without drive mechanisms if they have a beneficial effect on their carriers in small numbers but start to be detrimental in high copy numbers. Empirical data reviewed in this paper supports both models providing evidence for the selfish spread of B chromosomes in populations through drive in many species ( Hasegawa, 1934 ; Nur, 1962 ; Nur, 1963 ; Rutishauser and Rӧthlisberger, 1966 ; Nur, 1969 ; Kayano, 1971 ; Jones and Rees, 1982 ; Gregg at al., 1984 ; Murray, 1984 ; Viseras et al, 1990 ; Jones, 1991 ; Pardo et al, 1995 ; Houben, 2017 ; Jones, 2018 ; Clark and Kocher, 2019 ; Blavet et al, 2021 ) as well as identifying beneficial effects of B chromosomes for their hosts ( Williams, 1970 ; Dherawattana and Sadanaga, 1973 ; Rees and Hutchinson, 1974 ; Holmes and Bougourd, 1989 ; Miao et al, 1991 ; Plowman and Bougourd, 1994 ; Enkerli et al, 1997 ; Hatta et al, 2002 ; Nokkala et al, 2003 ; Rodriguez-Carres et al, 2008 ; Akagi et al, 2009 ; Coleman et al, 2009 ; Ma et al, 2010 ; Balesdent et al, 2013 ; Thatcher et al, 2016 ; Williams et al, 2016 ; Dalíková et al, 2017 ; Pereira et al, 2017 ; van Dam et al, 2017 ; Armitage et al, 2018 ; Kinsella et al, 2019 ; Torgasheva et al, 2019 ; Imarazene et al, 2021 ; Lewis et al, 2021 ). From the example in rye where B chromosomes have beneficial function but are still driving ( Pereira et al, 2017 ) we see that there could be even co-occurrence of drive and beneficial function which indicates the rather extensive complexity of B chromosome evolution.…”

Section: Introductionmentioning

confidence: 99%

Evolution of B Chromosomes: From Dispensable Parasitic Chromosomes to Essential Genomic Players

Pokorná

Reifová

2021

Front. Genet.

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B chromosomes represent additional chromosomes found in many eukaryotic organisms. Their origin is not completely understood but recent genomic studies suggest that they mostly arise through rearrangements and duplications from standard chromosomes. They can occur in single or multiple copies in a cell and are usually present only in a subset of individuals in the population. Because B chromosomes frequently show unstable inheritance, their maintenance in a population is often associated with meiotic drive or other mechanisms that increase the probability of their transmission to the next generation. For all these reasons, B chromosomes have been commonly considered to be nonessential, selfish, parasitic elements. Although it was originally believed that B chromosomes had little or no effect on an organism’s biology and fitness, a growing number of studies have shown that B chromosomes can play a significant role in processes such as sex determination, pathogenicity and resistance to pathogens. In some cases, B chromosomes became an essential part of the genome, turning into new sex chromosomes or germline-restricted chromosomes with important roles in the organism’s fertility. Here, we review such cases of “cellular domestication” of B chromosomes and show that B chromosomes can be important genomic players with significant evolutionary impact.

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Section: Introductionmentioning

confidence: 99%

Evolution of B Chromosomes: From Dispensable Parasitic Chromosomes to Essential Genomic Players

Pokorná

Reifová

2021

Front. Genet.

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“…To date, at least seven pathotypes have been described, each producing a unique HST essential to pathogenicity in apples ( AMT ), Japanese pears (AKT ), strawberries ( AFT ), tangerines ( ACT ), tomatoes ( AAL ) rough lemons ( ACR ) and tobacco ( AT ) ( Tsuge et al, 2013 ; Wang et al, 2019 ). The production of these HSTs involves a cluster of genes located on conditionally (or accessory) dispensable chromosomes (CDCs), so named because they are not essential for saprophytic growth and reproduction of pathogens ( Hatta et al, 2002 ; Wang et al, 2019 ).…”

Section: Introductionmentioning

confidence: 99%

Identification and pathogenicity of Alternaria species associated with leaf blotch disease and premature defoliation in French apple orchards

Fontaine¹,

Fourrier‐Jeandel²,

Armitage

et al. 2021

PeerJ

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Leaf blotch caused by Alternaria spp. is a common disease in apple-producing regions. The disease is usually associated with one phylogenetic species and one species complex, Alternaria alternata and the Alternaria arborescens species complex (A. arborescens SC), respectively. Both taxa may include the Alternaria apple pathotype, a quarantine or regulated pathogen in several countries. The apple pathotype is characterized by the production of a host-selective toxin (HST) which is involved in pathogenicity towards the apple. A cluster of genes located on conditionally dispensable chromosomes (CDCs) is involved in the production of this HST (namely AMT in the case of the apple pathotype). Since 2016, leaf blotch and premature tree defoliation attributed to Alternaria spp. have been observed in apple-producing regions of central and south-eastern France. Our study aimed to identify the Alternaria species involved in apple tree defoliation and assess the presence of the apple pathotype in French orchards. From 2016 to 2018, 166 isolates were collected and identified by multi-locus sequence typing (MLST). This analysis revealed that all these French isolates belonged to either the A. arborescens SC or A. alternata. Specific PCR detection targeting three genes located on the CDC did not indicate the presence of the apple pathotype in France. Pathogenicity was assessed under laboratory conditions on detached leaves of Golden Delicious and Gala apple cultivars for a representative subset of 28 Alternaria isolates. All the tested isolates were pathogenic on detached leaves of cultivars Golden Delicious and Gala, but no differences were observed between the pathogenicity levels of A. arborescens SC and A. alternata. However, the results of our pathogenicity test suggest that cultivar Golden Delicious is more susceptible than Gala to Alternaria leaf blotch. Implications in the detection of the Alternaria apple pathotype and the taxonomic assignment of Alternaria isolates involved in Alternaria leaf blotch are discussed.

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“…Tenuazonic acid, tentoxin, and brefeldin A are some examples of non-specific toxins secreted by Alternaria spp., which are phytotoxic in nature ( Meronuck et al, 1972 ; Fujiwara et al, 1988 ). Host-specific toxins (HSTs) such as AK-toxin, AF-toxin, ACT-toxin, AM-toxin, AAL-toxin are secreted by various pathotypes of A. alternata ( Tanaka and Tsuge, 2000 ; Hatta et al, 2002 ; Thomma, 2003 ). HSTs have been shown to be the major pathogenicity factors in A. alternata and disruption of the genes coding for these HSTs leads to loss of pathogenicity.…”

Section: Introductionmentioning

confidence: 99%

Functional Characterization of the Nep1-Like Protein Effectors of the Necrotrophic Pathogen – Alternaria brassicae

et al. 2021

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Alternaria brassicae is an important necrotrophic pathogen that infects the Brassicaceae family. A. brassicae, like other necrotrophs, also secretes various proteinaceous effectors and metabolites that cause cell death to establish itself in the host. However, there has been no systematic study of A. brassicae effectors and their roles in pathogenesis. The availability of the genome sequence of A. brassicae in public domain has enabled the search for effectors and their functional characterization. Nep1-like proteins (NLPs) are a superfamily of proteins that induce necrosis and ethylene biosynthesis. They have been reported from a variety of microbes including bacteria, fungi, and oomycetes. In this study, we identified two NLPs from A. brassicae viz. AbrNLP1 and AbrNLP2 and functionally characterized them. Although both AbrNLPs were found to be secretory in nature, they localized differentially inside the plant. AbrNLP2 was found to induce necrosis in both host and non-host species, while AbrNLP1 could not induce necrosis in both species. Additionally, AbrNLP2 was shown to induce pathogen-associated molecular pattern (PAMP)-triggered immunity in both host and non-host species. Overall, our study indicates that AbrNLPs are functionally and spatially (subcellular location) distinct and may play different but important roles during the pathogenesis of A. brassicae.

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

Cited by 198 publications

References 56 publications

Evolution of B Chromosomes: From Dispensable Parasitic Chromosomes to Essential Genomic Players

Evolution of B Chromosomes: From Dispensable Parasitic Chromosomes to Essential Genomic Players

Identification and pathogenicity of Alternaria species associated with leaf blotch disease and premature defoliation in French apple orchards

Functional Characterization of the Nep1-Like Protein Effectors of the Necrotrophic Pathogen – Alternaria brassicae

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