Sex in Fungi - MBY 261 PDF

Sex in Fungi Theme 6a MBY 261 Dr Gerda Fourie  Sex in Fungi – study outcomes  Sexual reproduction in fungi (Ascomycota and Basidiomycota)  Mating type idiomorphs and the basic functions of mating type genes  Processes involves - mate recognition, cell to cell fusi...

Sex in Fungi Theme 6a MBY 261 Dr Gerda Fourie  Sex in Fungi – study outcomes  Sexual reproduction in fungi (Ascomycota and Basidiomycota)  Mating type idiomorphs and the basic functions of mating type genes  Processes involves - mate recognition, cell to cell fusion to yield a zygote, and meiosis to generate gametes and ploidy changes  Heterothallic, primary homothallic, pseudohomothallic, bi-directional mating-type switching, unidirectional mating type switching and unisexual reproduction  Why sexual reproduction is important  Sex in Fungi – study outcomes  Sexual reproduction in fungi (Ascomycota and Basidiomycota)  Mating type idiomorphs and the basic functions of mating type genes  Processes involves - mate recognition, cell to cell fusion to yield a zygote, and meiosis to generate gametes and ploidy changes  Heterothallic, primary homothallic, pseudohomothallic, bi-directional mating-type switching, unidirectional mating type switching and unisexual reproduction  Why sexual reproduction is important  Sex in Fungi  Sexual reproduction evolved early in the Eukaryotic lineage  Sex in Fungi  Requires recognition between cells (self/non-self) of opposite mating types (MAT 1 and MAT 2) AND nuclei in a common cytoplasm  MAT 1 and MAT 2 male and female  Most fungi are hermaphroditic (male/female)  Female partner – trichogyne that develops from a protopertithecium  Male – conidium or hyphal cell  Mating type genes and their function MAT 1 locus: MAT1-1-1 MAT1-1-2 MAT1-1 idiomorph harbors a conserved alpha domain MAT1-2-1 MAT1-2-2 MAT1-2 idiomorph harbors a conserved HMG box  Idiomorphs = different genes  Locus = a specific region on a chromosome that defines an area harboring a gene  Allele = alternative form of a gene  Mating type genes and their function They are transcription factors = gene expression by regulating the transcription of specific genes Opposite mating types active different genes involved in mating DNA is transcribed into RNA RNA is translated into proteins Transcription factor Proteins = building blocks of life = enables function Life cycle of Ascomycota Dikaryotic stage Key = Haploid (n) = Diploid (2n) = Dikaryotic  Mating type genes and their function Outcrossing and Inbreeding (self-fertile)  Mating type genes and their function cell-cell fusion Dikaryotic Dikaryotic stage stage mate recognition meiosis Key = Haploid (n) = Diploid (2n) Spore maturation and release = Heterokaryotic  Sexual reproduction – mate OR cell recognition  Pheromone-based communication between individuals of opposite mating types Pheromone chemical signals are also used by insects for mating = development of pheromone-based traps for monitoring and/or control of insects (Wilson et al. 2019 Genes doi:10.3390/genes10050330)  Sexual reproduction – mate OR cell recognition (Wilson et al. 2019 Genes doi:10.3390/genes10050330) MAT1-1 idiomorph MAT1- 2 idiomorph Male express the pheromone Female express the pheromone receptor (diffusible peptides)  Male conidia attacks the female hyphae  Sexual reproduction – mate OR cell recognition MAT1-1 idiomorph = male partner MAT1-2 idiomorph = female partner MAT1-1 idiomorph = female partner MAT1-2 idiomorph = male partner  Stimulate growth towards a suitable partner  Growth = Redistribution of energy, cell wall remodeling and preparation of the sexual tissue  Mating type genes and their function cell-cell fusion Dikaryotic Dikaryotic stage stage mate recognition meiosis Key = Haploid (n) = Diploid (2n) Spore maturation and release = Heterokaryotic  Sexual reproduction – cell to cell fusion Plasmogamy Fertilization Fruiting body trichogyne develops from the protoperithecium  Males cell nucleus enters the trichogyne  Nuclei divide in the cytoplasm until a fruiting body is formed, but the nuclei have not fused yet (Dikaryotic stage)  Fruiting body Naked Ascus Cleistothecium Pseudothecium Perithecium Apothecium Sphaerotheca spp. Venturia spp. Peziza spp. Taphrina spp. Uncinula spp. Mycosphaerella spp. Sordaria spp. Neolecta spp.. (Diversity in fungi – Lecture 5a – Prof van den Berg)  Sexual reproduction – cell to cell fusion Karyogamy  Nuclei from opposite mating type discriminate self from non-self  The apical cell of the ascogenous cells differentiate into a hook-like crozier  Nuclei fuse to form diploid zygote  Mating type genes and their function cell-cell fusion Dikaryotic Dikaryotic stage stage mate recognition meiosis Key = Haploid (n) = Diploid (2n) Spore maturation and release = Heterokaryotic  Sexual reproduction – meiosis  Cell differentiates into a meiocyte and meiosis occurs  Meiosis = reduction and division, the diploid meiocyte divides into four genetically different haploid gametes  Mitosis follow meiosis and the mature ascus therefore contains 8 spores (4 sets of twins) Sexual reproduction - Basidiomycetes MATE RECOGNITION extended dikaryotic phase  Sexual reproduction - Basidiomycetes  Mating types Polar Mating Types: Two mating types referred to as "plus" and "minus" Tetrapolar Mating Types: Agaricus bisporus - the white button mushroom Two independent loci = A and B with allelic variants  Sexual reproduction - Basidiomycetes Tetrapolar Mating Types: Ax and Ay are different alleles Alternative form of a gene Bx and By are different alleles DNA is transcribed into RNA RNA is translated into proteins Proteins = building blocks of life = enables function Ax and Ay  Sexual reproduction - Basidiomycetes  Mating types Polar Mating Types: Two mating types referred to as "plus" and "minus" Tetrapolar Mating Types: Agaricus bisporus - the white button mushroom Two independent loci = A and B with allelic variants Four spore types: AxBx AxBy AyAx AyBy  Sexual reproduction - Basidiomycetes Tetrapolar Mating Types: Agaricus bisporus - the white button mushroom AxBx AyBx AxBy AyBy AxBx Incompatible Semi-incompatible Semi-incompatible Compatible  Sex in Fungi – study outcomes  Sexual reproduction in fungi (Ascomycota and Basidiomycota)  Mating type idiomorphs and the basic functions of mating type genes  Processes involves - mate recognition, cell to cell fusion to yield a zygote, and meiosis to generate gametes and ploidy changes  Heterothallic, primary homothallic, pseudohomothallic, bi-directional mating-type switching, unidirectional mating type switching and unisexual reproduction  Why sexual reproduction is important