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Philippe Callac - One of the best experts on this subject based on the ideXlab platform.
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Offspring analysis using two cleaved amplified polymorphic sequence (CAPS) markers reveals amphithallism in the edible mushroom Agaricus sinodeliciosus
Mycologia, 2019Co-Authors: Zhi-lin Ling, Philippe Callac, Hui-jun Wang, Rui-lin ZhaoAbstract:Agaricus sinodeliciosus is an edible wild mushroom known in northwest China. It belongs to Agaricus section Bivelares that includes several popular cultivated species, such as A. bisporus, the button mushroom. The life cycle of the latter species has been described as amphithallic because both Homokaryotic (n) and heterokaryotic (n+n) spores are produced that lead to heterothallic and pseudohomothallic life cycles, respectively. The type of life cycle can impact population structures and breeding strategies. The main objective of this study was to identify the different categories of spores produced by A. sinodeliciosus. Using either a morphological approach based on the number of sterigmata per basidium or a genetic approach based on the genotypes of the progeny at two loci, the proportion of heterokaryotic spores was estimated at 6% and 15%, respectively. Two codominant markers were chosen from the mitochondrial intermediate peptidase gene (MIP) and the nuc rDNA internal transcribed spacer (ITS1-5.8S-ITS2 = ITS) region. Genotypic analysis and mating tests confirmed that in A. sinodeliciosus, MIP is centromere-linked and tightly linked to the mating type locus as in A. bisporus and A. subrufescens. We conclude that A. sinodeliciosus has a unifactorial system of sexual incompatibility and an amphithallic life cycle that is predominantly heterothallic, and that its pseudohomothallism follows a nonrandom model with nonsister postmeiotic nuclei paired in the same spore, which give rise to a potentially fertile heterokaryon. This method of using two informative markers is reliable not only in selecting the Homokaryotic offspring but also in classifying the homokaryons in two breeding stocks according to their mating type alleles.
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Spore behaviors reveal a category of mating-competent infertile heterokaryons in the offspring of the medicinal fungus Agaricus subrufescens
Applied Microbiology and Biotechnology, 2016Co-Authors: Manuela Rocha De Brito, Marie Foulongne-oriol, Magalie Moinard, Eustáquio Souza Dias, Jean-michel Savoie, Philippe CallacAbstract:Strain breeding is much less advanced in the edible and medicinal species Agaricus subrufescens than in Agaricus bisporus , the button mushroom. Both species have a unifactorial system of sexual incompatibility, a mating type locus tightly linked to a centromere, and basidia producing both Homokaryotic ( n ) and heterokaryotic ( n + n ) spores. In A. bisporus , breeding is mainly based on direct selection among the heterokaryotic offspring and on hybridization between Homokaryotic offspring. The parental heterozygosity is highly maintained in the heterokaryotic offspring due to suppression of recombination and preferential pairing in the spores of nuclei, each one per second meiotic divisions; such “non-sister nuclei” heterokaryons are fertile. In A. subrufescens , recent studies revealed that recombination is not suppressed and that nuclei from the same second meiotic division can also be paired in a spore that give rise to a “sister nuclei” heterokaryon in which the nuclei bear the same mating type allele. The objective of the present work was to investigate the potential function of the different categories of spores in A. subrufescens and their possible use in a genetic breeding program. Using eight co-dominant molecular markers, we found that half of the offspring of the A. subrufescens strain WC837 were heterokaryotic, one quarter of them being sister nuclei heterokaryons. These heterokaryons were infertile and behaved like homokaryons, being even able to cross between each other. In contrast, non-sister nuclei heterokaryons could fruit but inconsistently due to inbreeding depression. Potential roles of these two categories of heterokaryons in nature and consequences for strain breeding are discussed.
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Evidence for Outcrossing via the Buller Phenomenon in a Substrate Simultaneously Inoculated with Spores and Mycelium of Agaricus bisporus
Applied and Environmental Microbiology, 2006Co-Authors: Philippe Callac, Cathy Spataro, Aurélie Caille, Micheline ImbernonAbstract:In Agaricus bisporus, traditional cultivars and most of the wild populations belong to A. bisporus var. bisporus, which has a predominantly pseudohomothallic life cycle in which most meiospores are heterokaryons (n + n). A lower proportion of Homokaryotic (n) meiospores, which typify the heterothallic life cycle, also are produced. In wild populations, pseudohomothallism was thought previously to play a major role, but recent analyses have found that significant outcrossing also may occur. We inoculated a standard substrate for A. bisporus cultivation simultaneously with Homokaryotic mycelium from one parent and spores from a second parent. Culture trays produced numerous sporocarps that could theoretically have resulted from five different reproductive modes (pseudohomothallism, selfing or outcrossing via heterothallism, and selfing or outcrossing via the Buller phenomenon [i.e., between a homokaryon and a heterokaryon]). Most or all of the sporocarps resulted from outcrossing between the inoculated homokaryon and the inoculated heterokaryotic spores (or mycelia that grew from them). These data broaden our understanding of population dynamics under field conditions and provide an outcrossing method that could be used in commercial breeding programs.
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A novel homothallic variety of Agaricus bisporus comprises rare tetrasporic isolates from Europe.
Mycologia, 2003Co-Authors: Philippe Callac, Isabelle Jacobé De Haut, Micheline Imbernon, Jacques Guinberteau, Christophe Desmerger, Ioanna TheochariAbstract:Among 400 wild specimens of A. bisporus collected in Europe, only three were tetrasporic. In the case of two of them from France, a previous study showed that one was Homokaryotic and hypothetically belonged to a homothallic entity while the other was heterokaryotic and possibly resulted from hybridization between a member of this entity and a classical bisporic strain. A third tetrasporic specimen recently was discovered in Greece. Morphological and genetic comparisons, using alloenzymatic markers, molecular markers and ITS polymorphisms, reveal that this third specimen is Homokaryotic and belongs, with the Homokaryotic specimen from France, to the same entity. Dissimilarity analysis confirms the hybrid origin of the heterokaryotic specimen. Varietal status is proposed for this homothallic, highly homogeneous entity, and A. bisporus var. eurotetrasporus is described. This novel variety clearly differs from var. bisporus by its tetrasporic basidia and from var. burnettii by its longer spores. It has a complex story because it can interbreed with var. bisporus and shares the same habitat; however, because of its homothallic life cycle and its partial intersterility, it is probably in the process of speciation.
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Bsn-t alleles from french field strains of agaricus bisporus
Applied and Environmental Microbiology, 1998Co-Authors: Philippe Callac, Micheline Imbernon, Christophe Desmerger, Sophie Hocquart, Jean-marc OlivierAbstract:In the Agaricus bisporus desert population in California, the dominant Bsn-t allele determines the production of tetrasporic basidia and Homokaryotic spores (n) that characterize a heterothallic life cycle. Strains belonging to a French population have the Bsn-b/b genotype that results in bisporic basidia that produce heterokaryotic spores (n + n) which characterize a pseudohomothallic life cycle. More recombination occurs in the tetrasporic population than in the bisporic population. In France, tetrasporic strains are rare. For two such isolates, Bs 261 and Bs 423, we determined the life cycle, the heritability of the tetrasporic trait, the amount of variation in the recombination rate, and the haploid fruiting ability. We found that (i) Bs 261 was heterothallic, (ii) Bs 423 was Homokaryotic and homothallic, (iii) Bs 261 was Bsn-t/b, (iv) recombination on a segment of chromosome I depended on the genotype at BSN, (v) some of the Homokaryotic offspring of Bs 261 and all of the progeny of Bs 423 were able to fruit, (vi) Bs 261 and Bs 423 were closely related, and (vii) Bs 423 was partially intersterile with other strains of the species.
Jaap Keijer - One of the best experts on this subject based on the ideXlab platform.
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Mating type-correlated molecular markers and demonstration of heterokaryosis in the phytopathogenic fungus Thanatephorus cucumeris (Rhizoctonia solani) AG 1-IC by AFLP DNA fingerprinting analysis
Journal of Biotechnology, 1999Co-Authors: M.c. Julian, Jaap Keijer, Javier Acero, Oscar Salazar, Víctor RubioAbstract:The destructive soil-borne plant pathogenic basidiomycetous fungus Thanatephorus cucumeris (Frank) Donk [anamorph: Rhizoctonia solani Kuhn] is not a homogeneous species, but is composed of at least twelve anastomosis groups (AG), which seem to be genetically isolated. The genetics of several T. cucumeris anastomosis groups has been studied by analysis of heterokaryotic tuft formation in the area of contact between Homokaryotic single-spore isolates, revealing that AG 1 is heterokaryotic and bipolar. To prove that tuft formation is due to heterokaryosis, AFLP DNA fingerprinting has been applied to a heterokaryotic T. cucumeris AG 1-IC isolate, its Homokaryotic single spore-derived progeny, and newly formed heterokaryons. By means of AFLP markers, it is demonstrated that fluffy tufts formed upon pairing of homokaryons from different mating types are newly formed heterokaryons. Mating type-correlated markers have also been found, which will be useful for future studies of the genetics of this fungal species complex.
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Independence of sexual and vegetative incompatibility mechanisms of Thanatephorus cucumeris (Rhizoctonia solani) anastomosis group 1
Phytopathology, 1996Co-Authors: M.c. Julian, F. Debets, Jaap KeijerAbstract:The soilborne plant pathogen Thanatephorus cucumeris (anamorph Rhizoctonia solani) is a basidiomycete that occurs worldwide and causes damage to a large variety of agricultural crops. The lack of knowledge of the genetic basis of incompatibility in T. cucumeris hampers the development of environmentally friendly control measures for this plant pathogen. To clarify incompatibility mechanisms in T. cucumeris, sexual and vegetative compatibility were investigated simultaneously in anastomosis group (AG)-I. Sporulation was induced in vitro for a field isolate belonging to AG-I, and single spores were isolated, giving rise to Homokaryotic colonies. The homokaryons were paired, and the contact area between isolates was studied macro- and microscopically. Mating processes (formation of heterokaryotic tufts between paired homokaryons) occurred independently from vegetative incompatibility processes (lysis of anastomosed cells), showing that in T. cucumeris AG-1 sexual and vegetative incompatibility are two mechanisms that operate independently. Vegetative incompatibility was variable and irreproducible, indicating vegetative compatibility in T. cucumeris AG-1 is a complex mechanism. Furthermore, heterokaryotization of Homokaryotic mycelium (Buller phenomenon) was observed. A novel phenomenon is described, consisting of the spontaneous lysis of the cells of some of the Homokaryotic progeny of the field isolate.
M.c. Julian - One of the best experts on this subject based on the ideXlab platform.
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Mating type-correlated molecular markers and demonstration of heterokaryosis in the phytopathogenic fungus Thanatephorus cucumeris (Rhizoctonia solani) AG 1-IC by AFLP DNA fingerprinting analysis
Journal of Biotechnology, 1999Co-Authors: M.c. Julian, Jaap Keijer, Javier Acero, Oscar Salazar, Víctor RubioAbstract:The destructive soil-borne plant pathogenic basidiomycetous fungus Thanatephorus cucumeris (Frank) Donk [anamorph: Rhizoctonia solani Kuhn] is not a homogeneous species, but is composed of at least twelve anastomosis groups (AG), which seem to be genetically isolated. The genetics of several T. cucumeris anastomosis groups has been studied by analysis of heterokaryotic tuft formation in the area of contact between Homokaryotic single-spore isolates, revealing that AG 1 is heterokaryotic and bipolar. To prove that tuft formation is due to heterokaryosis, AFLP DNA fingerprinting has been applied to a heterokaryotic T. cucumeris AG 1-IC isolate, its Homokaryotic single spore-derived progeny, and newly formed heterokaryons. By means of AFLP markers, it is demonstrated that fluffy tufts formed upon pairing of homokaryons from different mating types are newly formed heterokaryons. Mating type-correlated markers have also been found, which will be useful for future studies of the genetics of this fungal species complex.
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Independence of sexual and vegetative incompatibility mechanisms of Thanatephorus cucumeris (Rhizoctonia solani) anastomosis group 1
Phytopathology, 1996Co-Authors: M.c. Julian, F. Debets, Jaap KeijerAbstract:The soilborne plant pathogen Thanatephorus cucumeris (anamorph Rhizoctonia solani) is a basidiomycete that occurs worldwide and causes damage to a large variety of agricultural crops. The lack of knowledge of the genetic basis of incompatibility in T. cucumeris hampers the development of environmentally friendly control measures for this plant pathogen. To clarify incompatibility mechanisms in T. cucumeris, sexual and vegetative compatibility were investigated simultaneously in anastomosis group (AG)-I. Sporulation was induced in vitro for a field isolate belonging to AG-I, and single spores were isolated, giving rise to Homokaryotic colonies. The homokaryons were paired, and the contact area between isolates was studied macro- and microscopically. Mating processes (formation of heterokaryotic tufts between paired homokaryons) occurred independently from vegetative incompatibility processes (lysis of anastomosed cells), showing that in T. cucumeris AG-1 sexual and vegetative incompatibility are two mechanisms that operate independently. Vegetative incompatibility was variable and irreproducible, indicating vegetative compatibility in T. cucumeris AG-1 is a complex mechanism. Furthermore, heterokaryotization of Homokaryotic mycelium (Buller phenomenon) was observed. A novel phenomenon is described, consisting of the spontaneous lysis of the cells of some of the Homokaryotic progeny of the field isolate.
Akira Ohta - One of the best experts on this subject based on the ideXlab platform.
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bipolar incompatibility system of an ectomycorrhizal basidiomycete rhizopogon rubescens
Mycorrhiza, 2008Co-Authors: Masataka Kawai, Mina Yamahara, Akira OhtaAbstract:The mating systems of most ectomycorrhizal fungi have not been elucidated because of two reasons. One is the difficulty of obtaining Homokaryotic isolates for mating tests caused by the low germination rate of basidiospores, and another is the difficulty of checking dikaryotization caused by the absence or inconsistent production of clamp connections on heterokaryotic mycelia under laboratory conditions. Basidiospore germination of a few ectomycorrhizal fungi has been induced by living roots of their host plants. Based on this information, we examined methods to obtain Homokaryotic isolates of Rhizopogon rubescens using its host plant, Pinus thunbergii. The basidiospores of R. rubescens appeared to germinate well on an agar plate, on which axenic pine seedlings were grown in advance to induce germination, even when the seedlings were removed from the plate at the time of spore inoculation. To enhance the production rate of clamp connections on the heterokaryotic mycelia of R. rubescens, the culture medium composition was modified. The pH of the medium was critical for the production of clamp connections, and the optimal pH was higher for the production of clamp connections than for mycelial growth. These findings made it possible to conduct mating tests, and we found that the mating system of R. rubescens is bipolar with a multiallelic mating type factor.
Jill Gaskell - One of the best experts on this subject based on the ideXlab platform.
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Draft genome sequence of a monokaryotic model brown-rot fungus Postia (Rhodonia) placenta SB12
Genomics Data, 2017Co-Authors: Jill Gaskell, Phil Kersten, Luis Larrondo, Paulo Canessa, Diego Martínez, David Hibbett, Monika Schmoll, Christian Kubicek, Angel Martinez, Jagjit YadavAbstract:We report the genome of Postia (Rhodonia) placenta MAD-SB12, a Homokaryotic wood decay fungus (Basidiomycota, Polyporales). Intensively studied as a representative brown rot decayer, the gene complement is consistent with the rapid depolymerization of cellulose but not lignin.
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Isolation and characterization of Homokaryotic strains from the ligninolytic basidiomycete Ceriporiopsis subvermispora
Fems Microbiology Letters, 2001Co-Authors: Mario Tello, Daniela Seelenfreund, Sergio Lobos, Jill Gaskell, Daniel Cullen, Rafael VicuñaAbstract:Genetic analyses of the lignin-degrading fungus Ceriporiopsis subvermispora is complicated by a dikaryotic nuclear condition and the absence of spore forms. Previous investigations had identified a family of closely related sequences encoding manganese peroxidase (MnP), but the relationship between genes and allelic variants could not be experimentally established. Addressing this issue, Homokaryotic derivatives of C. subvermipora strain FP105752 were isolated from regenerated protoplasts. Designated CsA and CsB, their Homokaryotic nature was established by polymerase chain reaction amplification and sequence analysis of the allelic variants of three MnP genes. Isoelectrofocusing revealed fewer MnP isoenzymes in filtrates of homokaryon cultures relative to the parental strain. The Homokaryotic strains will simplify genetic analyses, particularly the identification of new genes.