Trisporic Acid and Mating in Zygomycetes

Johannes Wöstemeyer; Christine Schimek

doi:10.1128/9781555815837.ch26

Chapter 26 : Trisporic Acid and Mating in Zygomycetes

Authors: Johannes Wöstemeyer¹, Christine Schimek²

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Affiliations: 1: Chair of General Microbiology and Microbial Genetics, Friedrich-Schiller-Universität Jena, 07743 Jena, Germany; 2: Chair of General Microbiology and Microbial Genetics, Friedrich-Schiller-Universität Jena, 07743 Jena, Germany

Content Type: Monograph

Publication Year: 2007

Category: Fungi and Fungal Pathogenesis

Book DOI: 10.1128/9781555815837

Chapter DOI: 10.1128/9781555815837.ch26

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Abstract:

The Zygomycota received their name by analogy to the other fungal groups based on the overt morphology of their sexual apparatus. Sexuality is based on the interaction of two thalli of different mating types in the heterothallic species and on the interaction of two hyphae or hyphal branches in the same mycelium in homothallic species. Sexual reactions are described for members of all groups within the Zygomycetes, one of the two classes within the Zygomycota. In the (-) mating type, trisporic acid synthesis is achieved by oxidation of the hydroxyl group at the C1 residue of trisporol. Trisporoid synthesis has hitherto been studied mainly in cultures near the end of their developmental cycle. As the focus lay on elaborating the chemical nature and conversions, these experiments were strongly oriented towards the product side of the process, and a lot of care was therefore invested into finding optimal conditions for trisporoid production. The photoreceptors involved are neither carotene nor flavins as in the other photoreactions of this fungus. Functional studies of sexual differentiation and development in zygomycetes are severely compromised by deficits in the toolkit of genetic analysis. Protoplast fusion between strains of complementary mating types is suitable for elucidating if both sets of genetic information are compatible in a common individual.

Citation: Wöstemeyer J, Schimek C. 2007. Trisporic Acid and Mating in Zygomycetes, p 431-443. In Heitman J, Kronstad J, Taylor J, Casselton L (ed), Sex in Fungi. ASM Press, Washington, DC. doi: 10.1128/9781555815837.ch26

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Trisporic Acid and Mating in Zygomycetes

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Figure 26.1

Zygomycete mating structures in 5-day-old cultures grown on solid medium in continuous darkness. (a) Mucor mucedo progametangial and gametangial stages formed between + and − zygophores; bar, 250 μm. (b) Mycotypha africana, homothallic zygospores and earlier developmental stages formed between hyphae of the same individual; bar, 150 μm. (c) Parasitella parasitica zygospore formation in stages ranging from progametangia to mature zygospore (white arrowhead) between + and − hyphae; bar, 150 μm. (d) Parasitella parasitica early stages of sikyospore formation with a young sporangiophore of Mucor mucedo (black arrowhead); bar, 150 μm.

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Figure 26.1

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Figure 26.2

Early sexual morphogenesis in Phycomyces blakesleeanus. (a) Zygophore knots and young apposed progametangia; bar, 150 μm. (b) Apposed progametangia coiling around each other during elongation; bar, 100 μm. (c) Gametangia are delimited by septa at the tips of the now open yoke structure; bar, 100 μm.

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Figure 26.2

/content/10.1128/9781555815837.ch26.ch26fig03

Figure 26.3

Simplified schematic representation of the trisporic acid biosynthesis pathway in Blakeslea trispora. Shown are the structures of the B-derivative series of trisporoids. In the A derivatives, the residues at C13, R13, are H, H; in the C derivatives, R13 H, OH; in the D derivatives, R2 H, OH, R13 O; and in the E derivatives, R3 H, OH, R13 H, OH. The respective mating types where the reactions occur are indicated by a plus sign (+) or a minus sign (−) set beside the reaction arrow. The open arrows indicate an exchange of precursors between the mating types. The determination of the exact order of reactions between β-carotene and 4-dihydrotrisporin is under way (dashed arrows).

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Figure 26.3

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