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• In Rust fungi all members are plant parasites (obligate biotrophs).
• Robigus, the Roman god of rust, was honored on April 25 in the annual festival Robigalia.
• Rust fungi have major economic importance worldwide on agricultural crops.
• Rust fungi have complicated life cycles with or without gametangia.
• Rust fungi have complicated disease cycles often cycling on two unrelated hosts.
• There are over 5000 species in 140-150 genera of rust fungi.
• All rust fungi are obligate parasites and use a haustoria as a means of penetration
• All rust fungi parasitize on vascular plants (Gymnosperms and Angiosperms).
• Rust fungi have high host specificity, for example, forma specialis.
• Some rust fungi can produce macrocyclic life cycles with up to 4 spore stages and spermatia.
• All Rust fungi require a host for reproduction, heteroecious species require 2 different host (homokaryotic hyphae infect one host, heterokaryotic hyphae infect other host) autoacecious require one host.
• Rust fungi have heterogametangia, and are the only group within the Basidiomycota to have them.
• Septa in rust fungi have pulleywheel occlusions, no clamps, and no dolipore septa.
• Basidiospores in rust fungi are forcibly discharged.
• Genetics in rust fungi are assumed to be Bipolar and biallelic, with most being heterothallic and some being homothallic.
• Rust fungi have 5 sori stages:

  Spermagonia - Spermatia form male gametes (not really spores)

  aecia - aeciospores are binucleate spores that give rise to dikaryotic mycelium

  uredinia - urediniospores are binucleate; repeating spore stage gives rise to dikaryotic mycelium

  telia - teliospores are not a spore but a basidial apparatus

  basidia - basidiospores are thin walled spores that develope as a result of sexual reproduction
• Rust fungi can have three different types of life cycles:

  macrocyclic - have all 5 sori stages (spermagonia, aecia, uredinia, telia, and basidia)

  demicyclic - do not have uredinia but do have spermagonia, aecia, uredinia, telia and basidia

  microcyclic - have acea and uredinai but only sometimes spermatia, they do not have telia and basidia or spermatia telia and basidia
• the parts o the basidium include:

  probasidium (teliospore)

  • Nuclear state: N + N
  • process: karyogamy

  Metabasidium (promycelium)

  • Nuclear state: 2N
  • process: Karyogamy

  epibasidium (sterigmata)

  • Nuclear state: 4N
  • Process: Basidiospore formation
• The Pucciniaceae are identified by a teliospore stalked, one to two celled
• the Melampsoraceae have teliospores with no stalk; united laterally in crusts or columns
• the Coelosporaceae have a teliospore with no stalk, they also have internal promycelium (the teliospore is the promycelium)
• the Cummins consist of 10 families based on morphology of spermagonia
• the Bruns consist of two families based on molecular evidence these are the Pucciniaceae and the Melampsoraceae