The Experts below are selected from a list of 1500 Experts worldwide ranked by ideXlab platform

Joseph Heitman - One of the best experts on this subject based on the ideXlab platform.

  • mating system evolution all roads lead to selfing
    Current Biology, 2019
    Co-Authors: Marco A Coelho, Joseph Heitman
    Abstract:

    Summary Fungi reproduce via both heterothallic outcrossing and homothallic selfing modes, and transitions between the two are common throughout the tree of life. A new study reports that the transition from Heterothallism to homothallism is common and has repeatedly punctuated the evolutionary trajectory across a major lineage of the fungal kingdom.

  • Mechanisms of Homothallism in Fungi and Transitions between Heterothallism and Homothallism
    Sex in Fungi, 2014
    Co-Authors: Xiaorong Lin, Joseph Heitman
    Abstract:

    Sexual systems are classified into Heterothallism or homothallism in fungi. This chapter focuses on examples of homothallic fungi and how their sexuality is governed. Conversions between heterothallic and homothallic sexual cycles are common evolutionary transitions in fungi, and whether homothallism evolved from Heterothallism or vice versa is a controversial topic, and there is evidence supporting both hypotheses. The structural analyses of MAT sequences from homothallic and heterothallic Cochliobolus species support the hypothesis that Heterothallism is the ancestral state in this genus. This unique arrangement of the Aspergillus nidulans MAT locus led to the proposal that homothallism is the ancestral state and that a transition from homothallism to Heterothallism could have occurred in A. oryzae and A. fumigatus by gene loss, although neither species has a defined sexual cycle. Homothallic species may originate from heterothallic predecessors, and the homothallic lifestyle may have a selective advantage under certain ecological pressures. This hypothesis is consistent with the repeated occurrence of homothallism within numerous genera and the fact that many heterothallic fungi achieve homothallism in the form of pseudohomothallism by mating-type switching or packaging two compatible nuclei into one spore. Homothallic individuals contain all of the necessary genetic information for full sexual expression.

Jm. Moreau - One of the best experts on this subject based on the ideXlab platform.

  • Bipolar Heterothallism in Tapesia yallundae for the two varieties of the anamorph Pseudocercosporella herpotrichoides
    Fungal Biology, 1995
    Co-Authors: Jm. Moreau, Henri Maraite
    Abstract:

    Apothecia or apothecial primordia of Tapesia yallundae were produced in vitro on wheat straw incubated under artificial light between 5 and 12 degrees C. The genetic control of the sexual reproduction was initially investigated by pairwise combination of single-ascospore strains obtained from field-collected apothecia, representatives of two asci of the anamorph Pseudocercosporella herpotrichoides var. herpotrichoides and one ascus of the anamorph P. h. var. acuformis. Subsequently, two compatible single-ascospore strains of each variety of P. herpotrichoides were paired with isolates from lesions on plants collected in a naturally infested field in Belgium. The patterns of pairings between isolates of P. h. var. herpotrichoides in which mature apothecia were formed is consistent with bipolar Heterothallism as the mechanism controlling sexual compatibility in T. yallundae. The pairings between single-ascospore strains of P. h. var. acuformis produced only apothecial primordia, but also in a manner typical of bipolar Heterothallism. Some primordia developed into mature but sterile apothecia in one of those pairings. In further tests under similar conditions no apothecia or primordia were obtained in the pairings between single-ascospore strains and isolates of the latter variety, suggesting that ascocarp induction in P. h. var. acuformis requires some hitherto unknown environmental trigger, while P. h. var. herpotrichoides is less demanding. No pairings between strains of the two varieties of P. herpotrichoides produced apothecia or apothecial primordia.

  • Bipolar Heterothallism in Tapesia-yallundae for the 2 Varieties of the Anamorph Pseudocercosporella-herpotrichoides
    'Elsevier BV', 1995
    Co-Authors: Jm. Moreau, Maraite Henri
    Abstract:

    Apothecia or apothecial primordia of Tapesia yallundae were produced in vitro on wheat straw incubated under artificial light between 5 and 12 degrees C. The genetic control of the sexual reproduction was initially investigated by pairwise combination of single-ascospore strains obtained from field-collected apothecia, representatives of two asci of the anamorph Pseudocercosporella herpotrichoides var. herpotrichoides and one ascus of the anamorph P. h. var. acuformis. Subsequently, two compatible single-ascospore strains of each variety of P. herpotrichoides were paired with isolates from lesions on plants collected in a naturally infested field in Belgium. The patterns of pairings between isolates of P. h. var. herpotrichoides in which mature apothecia were formed is consistent with bipolar Heterothallism as the mechanism controlling sexual compatibility in T. yallundae. The pairings between single-ascospore strains of P. h. var. acuformis produced only apothecial primordia, but also in a manner typical of bipolar Heterothallism. Some primordia developed into mature but sterile apothecia in one of those pairings. In further tests under similar conditions no apothecia or primordia were obtained in the pairings between single-ascospore strains and isolates of the latter variety, suggesting that ascocarp induction in P. h. var. acuformis requires some hitherto unknown environmental trigger, while P. h. var. herpotrichoides is less demanding. No pairings between strains of the two varieties of P. herpotrichoides produced apothecia or apothecial primordia

H. Brun - One of the best experts on this subject based on the ideXlab platform.

  • bipolar Heterothallism in b group isolates of leptosphaeria maculans
    Plant Pathology, 1997
    Co-Authors: I. Somda, S. Harkous, H. Brun
    Abstract:

    Pairwise combinations were carried out between the eight isolates originating from each of three asci of the B-group of Leptosphaeria maculans. Some of the pairings produced mature pseudothecia when incubated on wheat straws at 18°C and under a 12-h photoperiod of blue light. Isolates within a given tetrad could be attributed to one of two sexual compatibility groups, on the basis of combinations of isolates leading to fertile crosses. Within each tetrad, mating type segregated in a 1:1 ratio, suggesting the existence of one mating type gene (MAT1) with two alleles MAT1-1 and MAT1-2. Under these same conditions, each individual isolate from an A-group ascus originating from Brassica juncea produced pseudothecia with one or other of two compatible A-group testers originating from B. napus. However, attempts to mate these eight A-group single-ascospore isolates with two B-group single-ascospore isolates of opposite mating types remained unsuccessful. This work is the first successful report of in vitro sexual reproduction between B-group isolates, and provides evidence for bipolar Heterothallism in B-group isolates of L. maculans. The implications of this mating protocol for genetic studies of B-group isolates and the consequences of this work for the taxonomy of L. maculans are discussed.

  • Bipolar Heterothallism in B‐group isolates of Leptosphaeria maculans
    Plant Pathology, 1997
    Co-Authors: I. Somda, S. Harkous, H. Brun
    Abstract:

    Pairwise combinations were carried out between the eight isolates originating from each of three asci of the B-group of Leptosphaeria maculans. Some of the pairings produced mature pseudothecia when incubated on wheat straws at 18°C and under a 12-h photoperiod of blue light. Isolates within a given tetrad could be attributed to one of two sexual compatibility groups, on the basis of combinations of isolates leading to fertile crosses. Within each tetrad, mating type segregated in a 1:1 ratio, suggesting the existence of one mating type gene (MAT1) with two alleles MAT1-1 and MAT1-2. Under these same conditions, each individual isolate from an A-group ascus originating from Brassica juncea produced pseudothecia with one or other of two compatible A-group testers originating from B. napus. However, attempts to mate these eight A-group single-ascospore isolates with two B-group single-ascospore isolates of opposite mating types remained unsuccessful. This work is the first successful report of in vitro sexual reproduction between B-group isolates, and provides evidence for bipolar Heterothallism in B-group isolates of L. maculans. The implications of this mating protocol for genetic studies of B-group isolates and the consequences of this work for the taxonomy of L. maculans are discussed.

Henri Maraite - One of the best experts on this subject based on the ideXlab platform.

  • Bipolar Heterothallism in Tapesia yallundae for the two varieties of the anamorph Pseudocercosporella herpotrichoides
    Fungal Biology, 1995
    Co-Authors: Jm. Moreau, Henri Maraite
    Abstract:

    Apothecia or apothecial primordia of Tapesia yallundae were produced in vitro on wheat straw incubated under artificial light between 5 and 12 degrees C. The genetic control of the sexual reproduction was initially investigated by pairwise combination of single-ascospore strains obtained from field-collected apothecia, representatives of two asci of the anamorph Pseudocercosporella herpotrichoides var. herpotrichoides and one ascus of the anamorph P. h. var. acuformis. Subsequently, two compatible single-ascospore strains of each variety of P. herpotrichoides were paired with isolates from lesions on plants collected in a naturally infested field in Belgium. The patterns of pairings between isolates of P. h. var. herpotrichoides in which mature apothecia were formed is consistent with bipolar Heterothallism as the mechanism controlling sexual compatibility in T. yallundae. The pairings between single-ascospore strains of P. h. var. acuformis produced only apothecial primordia, but also in a manner typical of bipolar Heterothallism. Some primordia developed into mature but sterile apothecia in one of those pairings. In further tests under similar conditions no apothecia or primordia were obtained in the pairings between single-ascospore strains and isolates of the latter variety, suggesting that ascocarp induction in P. h. var. acuformis requires some hitherto unknown environmental trigger, while P. h. var. herpotrichoides is less demanding. No pairings between strains of the two varieties of P. herpotrichoides produced apothecia or apothecial primordia.

Maraite Henri - One of the best experts on this subject based on the ideXlab platform.

  • Bipolar Heterothallism in Tapesia-yallundae for the 2 Varieties of the Anamorph Pseudocercosporella-herpotrichoides
    'Elsevier BV', 1995
    Co-Authors: Jm. Moreau, Maraite Henri
    Abstract:

    Apothecia or apothecial primordia of Tapesia yallundae were produced in vitro on wheat straw incubated under artificial light between 5 and 12 degrees C. The genetic control of the sexual reproduction was initially investigated by pairwise combination of single-ascospore strains obtained from field-collected apothecia, representatives of two asci of the anamorph Pseudocercosporella herpotrichoides var. herpotrichoides and one ascus of the anamorph P. h. var. acuformis. Subsequently, two compatible single-ascospore strains of each variety of P. herpotrichoides were paired with isolates from lesions on plants collected in a naturally infested field in Belgium. The patterns of pairings between isolates of P. h. var. herpotrichoides in which mature apothecia were formed is consistent with bipolar Heterothallism as the mechanism controlling sexual compatibility in T. yallundae. The pairings between single-ascospore strains of P. h. var. acuformis produced only apothecial primordia, but also in a manner typical of bipolar Heterothallism. Some primordia developed into mature but sterile apothecia in one of those pairings. In further tests under similar conditions no apothecia or primordia were obtained in the pairings between single-ascospore strains and isolates of the latter variety, suggesting that ascocarp induction in P. h. var. acuformis requires some hitherto unknown environmental trigger, while P. h. var. herpotrichoides is less demanding. No pairings between strains of the two varieties of P. herpotrichoides produced apothecia or apothecial primordia