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Lecture: Growth and Development, Part B Biology of Fungi BIOL 4848/6948 - Fall 2009 Sexual Development Sexual reproduction involves three fundamental processes: Fungal Growth and Development Plasmogamy - fusion of haploid cells - fusion of haploid nuclei Meiosis - reduction division Karyogamy Two fundamental points of sexual reproduction Nature Serves BIOL 4848/6948 (v. F09) Copyright © 2009 Chester R. Cooper, Jr. Sexual Development (cont.) Nature of sexuality Homothallic vs. heterothallic Governed by mating type genes (compatibility) Arrangement of mating types Bipolar compatibility - governed by a single gene locus where one of a non-allelic pair of genes (idiomorph) exists Tetrpolar compatibility - two mating type gene pairs of multiple idiomorphs BIOL 4848/6948 (v. F09) Copyright © 2009 Chester R. Cooper, Jr. Sexual Development (cont.) of sexuality as a survival mechanism BIOL 4848/6948 (v. F09) Copyright © 2009 Chester R. Cooper, Jr. Sexual Development (cont.) Mating type and hormonal control Chytridiomycota Allomyces is a homothallic fungus that produces separate male and female gametangia that release motile gametes Gametangia of Allomyces. Source: www.palaeos.com/ Fungi/Lists/Glossary/GlossaryG.html BIOL 4848/6948 (v. F09) Copyright © 2009 Chester R. Cooper, Jr. Sexual Development (cont.) Mating type and hormonal control Chytridiomycota (cont.) Females release a pheromone, serinin, that attracts the male gametes Male gametes move along a concentration gradient Sirenin and carotenoid color produced in male gametangia are produced from the same precursor, indicating mating type gene controls development of the sex organs BIOL 4848/6948 (v. F09) Copyright © 2009 Chester R. Cooper, Jr. BIOL 4848/6948 (v. F09) Copyright © 2009 Chester R. Cooper, Jr. 1 Lecture: Growth and Development, Part B Sexual Development (cont.) Oomycota Sexual Development (cont.) Hormonal control in Achlya (cont.) Once triggered by antheridiol, males release oogoniols that induce oogonia development Eventually, male branches (antherida) fuse with oogonia Homothallic or heterothallic, but in most cases produces a colony with both male and female sex organs (antheridia and oogonia) Mating type genes control capatibility Hormonal control in Achlya Female produces antheridiol causing the male to increase production of cellulase which induces hyphal branching to increase BIOL 4848/6948 (v. F09) BIOL 4848/6948 - Fall 2009 Copyright © 2009 Chester R. Cooper, Jr. Sexual Development (cont.) BIOL 4848/6948 (v. F09) Copyright © 2009 Chester R. Cooper, Jr. Sexual Development (cont.) Zygomycota Homothallic or heterothallic mating type genes that govern conversion of βcarotene to a prohormone Prohormone is eventually converted by mating-type specific gene to trisporic acid Trisporic acid volatilizes and causes hyphae of opposite mating type to grow towards one another and fuse to form a zygospore Two Oogonium and antheridium of Achlya. Source: www.palaeos.com/Fungi/Lists/Glossary/GlossaryG.html BIOL 4848/6948 (v. F09) Copyright © 2009 Chester R. Cooper, Jr. BIOL 4848/6948 (v. F09) Copyright © 2009 Chester R. Cooper, Jr. BIOL 4848/6948 (v. F09) Copyright © 2009 Chester R. Cooper, Jr. Trisporic acid hormonal system in mating within the Zygomycota. Sources: www.palaeos.com/Fungi/Lists/Glossary/GlossaryG.html and Deacon, 2006 BIOL 4848/6948 (v. F09) Copyright © 2009 Chester R. Cooper, Jr. 2 Lecture: Growth and Development, Part B BIOL 4848/6948 - Fall 2009 Sexual Development (cont.) Ascomycota Typically two mating types a cells and α cells characterized system is that of Saccharomyces Mating is controlled by the MAT gene locus of flanked by two other loci, MATa and MATα A copy of one loci is made and inserted into MAT gene locus - this is now the mating type of the cell This copy can switch out after each new bud cell is produced Best Mating type loci of Saccharomyces. Source: nitro.biosci.arizona.edu/courses/ EEB320-2005/Lecture13/lecture13.html BIOL 4848/6948 (v. F09) Copyright © 2009 Chester R. Cooper, Jr. BIOL 4848/6948 (v. F09) Copyright © 2009 Chester R. Cooper, Jr. Sexual Development (cont.) Ascomycota (cont.) MATα are responsible for producing: Peptide hormones a-factor and α-factor Hormone receptors Cell surface agglutinins α cells constitutively release α-factor that is recognized by a receptor on a cells a cells cease growth and arrest at G1 phase of the cell cycle, then release a-factor Diagram of life cycle of Saccharomyces. Source: nitro.biosci.arizona.edu/ courses/EEB320-2005/Lecture13/lecture13.html BIOL 4848/6948 (v. F09) Copyright © 2009 Chester R. Cooper, Jr. BIOL 4848/6948 (v. F09) Copyright © 2009 Chester R. Cooper, Jr. Sexual Development (cont.) Ascomycota (cont.) Different mating types then form outgrowths (“schmoo” cells) with strain specific agglutinins on their surfaces Agglutinins cause cells to bind to one another, which then leads to fusion (plasmogamy), followed by karyogamy (diploid formation) Subsequent induction of meiosis produces four ascospores “Schmoo cell”, formation of zygotes via fusion of yeast cells, and ascospores of Schizosaccharomyces. Sources: www.biomade.nl/AmphipathicProteins.htm, www.jbc.org, www.visualsunlimited.com/browse/vu227/vu227486.html and, BIOL 4848/6948 (v. F09) Copyright © 2009 Chester R. Cooper, Jr. BIOL 4848/6948 (v. F09) Copyright © 2009 Chester R. Cooper, Jr. 3 Lecture: Growth and Development, Part B BIOL 4848/6948 - Fall 2009 Diagram of life cycle of Saccharomyces. Source: www.brooklyn.cuny.edu/bc/ahp/LAD/C9/C9_tetrads.html BIOL 4848/6948 (v. F09) Copyright © 2009 Chester R. Cooper, Jr. BIOL 4848/6948 (v. F09) Copyright © 2009 Chester R. Cooper, Jr. BIOL 4848/6948 (v. F09) Copyright © 2009 Chester R. Cooper, Jr. Sexual Development (cont.) Basidiomycota Most are heterothallic having one or two mating type loci (typically termed A and B) with mulitiple idiomorphs at each locus (e.g., A1, A2, A3, etc.) Successful matings occur with different idiomorphs at each locus (e.g., A1, B1 x A2, B2) Different pairings of idiomorphs have allowed a dissection of the functions of the mating-type genes A locus - controls pairing and synchronous division of nuclei and initiation of clamp formation B locus - controls septal dissolution, fusion of clamp branches, and increased glucanase activity BIOL 4848/6948 (v. F09) Copyright © 2009 Chester R. Cooper, Jr. Mating reactions between haploid isolates of Armillaria ostoyae (with bifactorial mating system): 1. Incompatible mating (incompatibility factors A1B1 x A1B1). 2. hemicompatible I (incomp. factors A1B1 x A1B2). 3. hemicompatible II (incomp. factors A1B1 x A2B1). 4. compatible mating, resulting in diploid mycelium (incomp. factors A1B1 x A2B2).Source: www.padil.gov.au/viewPest.aspx?id=518 BIOL 4848/6948 (v. F09) Copyright © 2009 Chester R. Cooper, Jr. Species identification with the aid of mating test. 1. A. ostoyae haploid (lower) x A. borealis haploid (intersterile – no reaction). 2. A. ostoyae diploid (lower) x A. borealis haploid (intersterile – no reaction). 3. A. ostoyae haploid x A. ostoyae haploid (compatible – rapid diploidisation). 4. A. ostoyae diploid (lower) x A. ostoyae haploid (intersterile – slow diploidisation of the haploid tester) .Source: www.padil.gov.au/viewPest.aspx?id=518 BIOL 4848/6948 (v. F09) Copyright © 2009 Chester R. Cooper, Jr. 4