The structure of the incompatibility factors of Schizophyllum commune: Constitution of the three classes of B factors

Parag, Yair; Koltin, Y.

doi:10.1007/bf00266931

Cited by 22 publications

(12 citation statements)

References 7 publications

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“…Effects of the last three mutations extend over the entire B factor and their location could not be resolved by recombination. BaSM()-,02 (1)(2)(3)(4)(5)(6)(7)(8) gives no evidence of any function attributable to Bj3, and Ba function also appears altered to the extent that it interacts unilaterally with certain members of the series of Ba alleles. The lesion thus appears to involve both genes of the B factor.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Mutational Analysis of a Regulatory Gene for Morphogenesis in Schizophyllum

Raper¹,

Raper²

1973

Proc. Natl. Acad. Sci. U.S.A.

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Knowledge of the structure and function of a complex gene regulating sexual development in the mushroom, Schizophyllum commune, has come from the analysis of various mutations in a chromosomal region known as the BJ3 incompatibility gene. This gene is one of two linked genes, Ba and Bfl, that together comprise the B factor which regulates a developmental sequence known as the B-sequence. The B-sequence is normally "turned off" (Fig. 1 a-e), and each factor controls a part of the series (2). The Asequence comprises nuclear pairing (b), conjugate division (c), and formation of hook cell (c and d), and converges with the B-sequence in fusion of hook cell (e). The B-sequence consists of nuclear migration (a) and fusion of hook cells (e). Sexual development thus requires the operation of both Aand B-sequences, or A-on-B-on. The converse, no sexual expression in unmated haploid strains or in matings homozygous for A and B, is A-off-B-off.Profound biochemical alterations underlie the operation of the sequences and suggest shifts in the spectrum of genes expressed in the morphogenetic progression (3).The present report is concerned with regulatory activity of the B factor and the status of the B-sequence, B-off or B-on; consequently, the status of the A-sequence can be essentially ignored. The terms "off" and "on" as used here signify only the inactivity or operation of the developmental sequence; they are not meant to imply anything about the mode of action of the incompatibility factors.The two genes of the B factor, Ba and Bof, each with nine 1427 known alleles (4), appear to be functionally identical and to act independently. Thus, the matings B al-f#l x B al-#2, B al-#l x B a2-01, and B a3-#4 x B a5-36 lead to a common result: to "turn on" the B-sequence and the characteristic B-on morphology. Matings homozygous for a single B factor, e.g., B a3-f32 x B a3S-#2 fail to turn on the B-sequence, and the phenotype remains B-off.The manner in which the genes of the B factor operate to control the B-sequence of sexual morphogenesis is unknown, but a study of the mutative capabilities provides some clues. All of many mutant alleles recovered in a system designed to select for a change from B-off to B-on were constitutive for the B-sequence (5, 6). The selective system would also have revealed mutations to new wild-type alleles capable of interacting with the progenitor allele to turn on the B-sequence, but no such mutation was found. Each of the mutants in isolation has a continuously operating B-sequence, e.g., the mutation of wild allele B,#2----+ B#2(1) (the number in parentheses representing a type of mutation) renders the B-sequence always on and makes the mutant allele interactive with all wild Bf3 alleles, the progenitor Bg2 included. The B-always-on phenotype is characterized by stunted growth, irregular branching, disrupted septa, and continuous nuclear migration; when the A-sequence is also operative, B-always-on elicits fusion of hook cells (7).Several secondary mutations induced in mutant B-on alleles ...

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Section: Methodsmentioning

confidence: 99%

“…The two genes of the B factor, Ba and Bof, each with nine 1427 known alleles (4), appear to be functionally identical and to act independently. Thus, the matings B al-f#l x B al-#2, B al-#l x B a2-01, and B a3-#4 x B a5-36 lead to a common result: to "turn on" the B-sequence and the characteristic B-on morphology.…”

mentioning

confidence: 99%

Mutational Analysis of a Regulatory Gene for Morphogenesis in Schizophyllum

Raper¹,

Raper²

1973

Proc. Natl. Acad. Sci. U.S.A.

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“…Each of the component loci possesses a large number of natural specificities. In S. commune, which has been the most extensively studied among the higher fungi, the number of alleles found in nature has been estimated at 9 for the Aa locus (Raper, Baxter and Ellingboe, 1960), 32 for A3 (see appendix of the present paper) and 9 each for Brh and B/3 (Parag and Koltin, 1971). Thus approximately 288 (i.e.…”

Section: Introductionmentioning

confidence: 89%

“…Studies of the frequency and distribution of incompatibility alleles in a worldwide sample have led to an estimate of 9 alleles at the Act locus, with a range of 7 to 13 (Raper, Baxter and Ellingboe, 1960); 32 Afi alleles, with a range of 23 to 59 (see appendix to this paper); and 9 alleles each at Bcc and Bfl, which are believed to represent the total number of natural alleles (Parag and Koltin, 1971). The marked asymmetry both between factors (a total of 41 alleles within the A factor as compared to 18 within the B factor) and within one of the factors (9 Act and 32 46 alleles) is in apparent contradiction to the argument developed in the preceeding section, that asymmetry is an inefficient distribution of alleles with respect to the outbreeding potential.…”

Section: Sci-jizophyllum Commune: a Case Of Asymmetrymentioning

confidence: 99%

The organisation of the incompatibility factors in higher fungi: The effect of structure and symmetry on breeding

Stamberg

Koltin

1973

Heredity

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SUMMARYAn evaluation of the structure of incompatibility systems in the higher fungi and its effect on inbreeding and outbreeding indicates that: In unifactorial systems a one-locus structure, which permits 50 per cent, inbreeding, is preferable to a two-locus structure, which would permit inbreeding to rise above 50 per cent. In bifactorial systems a two-locus structure for each factor is advantageous because it makes possible a high outbreeding potential with a small number of alleles. The two-locus structure also confers flexibility on the inbreeding potential. A symmetrical distribution of alleles among the four loci of a two-locus bifactorial system allows for maximal outbreeding. The advantage of symmetry is most pronounced when the total number of allelic specificities is not large. The asymmetrical distribution of alleles among the four incompatibility loci of Schizophyllum commune suggests that its incompatibility system evolved from a one-locus unifactorial system. The Afi locus, with 32 alleles, is assumed to be the oldest locus; the remaining three loci, with 9 alleles each, are assumed to have come into operation within a short time of each other, at a later stage.

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“…There are three distinct classes of B mating-type factors, which are designated class I, class II and class III [1]. The class II and class III B factors may originate from class I B factors by some deletion or mutation [7] and both of the classes combine two distinctive BL and BK alleles (BLP and BKP) respectively with seven BK and BL alleles of class I respectively [1]. Di¡erent sets of genes are present in both of the BK and BL loci, and both of the loci of S. commune are predicted to encode multiple pheromones and pheromone receptors [8,9].…”

Section: Introductionmentioning

confidence: 99%

Indole- and caffeine-resistant mutations of Schizophyllum commune are involved in the behavior of a class III B mating-type factor in trp1 cells

Samadder¹

1998

FEMS Microbiology Letters

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We have reported that a parental strain of Schizophyllun commune T11 (trp1) is fully compatible with a strain T37 (BK1PL4, trp1), but indole-and caffeine-resistant mutants (In -13 and Caf -9 respectively) derived from the T11 are semicompatible with the same T37. The compound-resistant mutations, ind1 and cfn1, were linked to neither A nor B mating-type factors. In -13, Caf -9, and all of indole-and caffeine-resistant progenies (ind1, trp1; cfn1, trp1) were semicompatible with the T37, and compatible with a strain T40 (BK1PL4, TRP1) although the T40 contained the same class III B mating-type factor as the T37. The In -13 and Caf -9 were also semicompatible with any tester strains (BK1PL4, trp1) developed, and the resulting heterokaryons produced non-aggregated and semiaggregated masses of hyphae, respectively. In the mutant heterokaryons, nuclei were distributed irregularly especially in case of [trp1/trp1] background ; anucleate, uninucleate, binucleate and multinucleate cells were found with modified hyphae which contained a different type of septation (pseudoclamps and simple septa other than true clamps). We concluded that the ind1 and cfn1 mutations alter the normal behavior of one of class III B mating-type factors in Trp 3 cells. z

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The structure of the incompatibility factors of Schizophyllum commune: Constitution of the three classes of B factors

Cited by 22 publications

References 7 publications

Mutational Analysis of a Regulatory Gene for Morphogenesis in Schizophyllum

Mutational Analysis of a Regulatory Gene for Morphogenesis in Schizophyllum

The organisation of the incompatibility factors in higher fungi: The effect of structure and symmetry on breeding

Indole- and caffeine-resistant mutations of Schizophyllum commune are involved in the behavior of a class III B mating-type factor in trp1 cells

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