1. Littlefield and Heath 1979 Ultrastructure of Rust Fungi glycogen lipid Storage compounds – retaining nutrients

2. Nutrition of biotrophs Components are extracted through haustoria Nutrients are soluble and organic Extracellular degradation for cell penetration Extracellular factors establish/maintain a compatible infection Suppress senescence

3. Suppressing senescence www.mpiz-koeln.mpg.de/schlef/PSL_webpage.html

4. Livning substrates exploited by fungi What is the nutrient flow direction? http://www.ucmp.berkeley.edu/fungi/rhyniefungus.jpg

5. Arbuscular and ectomycorrhizal fungi

6. Amino acid biosynthesis

7. Secondary metabolites Glucose-derived – polysaccharides, peptidopolysaccharides, and sugar alcohols. Condensation products of acetate – derived from the acetate-malonate pathway of fatty acid synthesis, e.g. polyketides and phenolics. Condensation products of acetate derived from the mevalonic acid pathway, e.g. terpenes. Phenolics derived from the shikimic acid pathway of aromatic amino acid synthesis. Derivatives of other amino acid syntheses.

8. Secondary metabolites Pigments Hormones Toxins Co-regulated with sporulation

9. Secondary metabolites of Saccharomyces www.crc.dk/flab/ newpage13.htm

10. Genetics – study of heredity Transmission - the passage of traits from one generation to the next

11. Genetics – study of heredity Population - genetic diversity and change within natural populations

12. Genetics – study of heredity Molecular - details of gene structure and function

13. Our focus for genetics transmission and molecular genetics in experimental systems defining a population –organisms in culture –humungous fungus –vegetative incompatibility

14. Transmission genetics Typical characteristics of fungal genomes Small –S. cerevisiae 6 MB – 6000 genes –A. nidulans 13 MB – 12000 genes –H. sapiens 1300 MB – 30000 genes

15. Typical characteristics of fungal genomes Little repetitive DNA – single copy genes –50-60% of nuclear genome is transcribed into mRNA in S cerevisiae –33% in S. commune (basidiomycete) –1% in humans Introns –few, often none –small – 50-200bp vs ≥10 kb in mammals

16. Most higher fungi are vegetative haploids One genome copy per nucleus Alternatives? –Plants? –Algae? –Animals?

17. Risks of haploidy No backup copy in case of genetic damage from UV or chemical mutagens Yeasts tend to be diploid (S. cerevisiae except for lab strains) or have short G1 (S. pombe) Chant and Pringle JCB 129:751

18. Advantages of haploidy A multinucleate cell can expose genome to mutagens –most mutations are deleterious –select for advantageous mutations in a heterokaryotic system Phenotypes of recessive mutations are obvious in the vegetative state, without generating homozygous recessives Lab strains of S. cerevisiae now generally include a mutation which stabilizes the haploid state

19. Transmission genetics – passage of inheritance Similar to more familiar mammalian systems, with bulk of life cycle haploid ‘Genders' are ‘mating types’ –cells are biochemically distinct but morphologically identical

20. Fungal mating systems

21. No mating factors  A. nidulans Inbreeding possible –disadvantage – sex does not necessarily increase genetic diversity –advantage – can form resistant spores even if no mating partner is available –A. nidulans ascospores from 1995 still viable after 4°C storage, whereas conidia viability is severely reduced after several months at 4°C

22. One factor (zygo, asco, some basids) Bipolar mating system meiosis will give two types of segregants –N. crassa a and  –Rhizopus + and –

23. One factor (zygo, asco, some basids) Advantage – outbreeding Disadvantage – cannot produce resistant sexual spores unless a partner is available ‘Coping’ with one-factor mating systems –Some fungi have multiple alleles at the mating locus –Mating type switching in Saccharomyces

25. One factor (zygo, asco, some basids) In S. cerevisiae "a" cells produce a-factor, a peptide sexual hormone, and  -receptor; converse for  cells hormones/receptors interaction promotes schmooing, wall changes promote adhesion

26. Two factors, A/B (often in basids) Tetrapolar mating system  meiosis give four types of segregants A 1 B 1 :: A 2 B 2  A 1 B 1, A 1 B 2, A 2 B 1, A 2 B 2

27. A and B functions are distinct in homobasids (.....?) –A controls pairing and synchronous division of nuclei, hook cell formation; –B controls septal dissolution and hook cell fusion (  -glucanase activity) and nuclear migration

28. A and B functions are distinct in heterobasids (....?) –A controls pathogenicity; –B controls filamentous growth

29. Systems restricting outcrossing in one-factor mating type systems self-fertility  S. cerevisiae has "mating type switching" molecular basis  both mating genes have a storage site and an expression site. if the appropriate partner cell is not available when mating conditions are presented (how would this be detected?)will induce swi expression

30. Systems restricting outcrossing in one-factor mating type systems vegetative (somatic) incompatibility het genes are important for mating, but prevent vegetative fusion

31. Systems restricting outcrossing in one-factor mating type systems vegetative (somatic) incompatibility in Fusarium – vegetative incompatibility is important for maintaining distinct populations with different host specificities Fusarium oxysporum f. sp. groups

32. Mutants in experimental fungal systems spontaneous mutations or mutagenesis (uv, chemicals) each gene is named for 1st described mutation Example: gene for pigmentation is called “white” because the mutant lacked colouration

33. Different species, different naming system Saccharomyces cerevisiae Schizosaccharomyces pombe Aspergillus nidulans Neurospora crassa Generally, three-letters plus a letter or number – hypA, CDC2, cdc28