Lecture 8 – Rusts (Urediniales in Text, Pucciniomycotina in Tree of Life http://tolweb.org/Pucciniomycotina/20528) – Teliomycetes II Reading: Text, Chapter 5, http://tolweb.org/Pucciniomycotina/20528 http://www.cals.ncsu.edu/course/pp315/gene/ Objectives: Understand the function in pathogenesis and evolution of the pathogen of each of the five spore-producing stages in a full-cycle rust. Study Questions: 1. What are the 5 spore phases of the life cycle of Puccinia graminis? Which are monokaryotic, which are dikaryotic? Which phase overwinters? 2. Which is more likely to be macrocyclic – an autoecious rust or a heteroecious rust? Which is more likely to be demicyclic or microcyclic? 3. A forma specialis is a grouping within a species that is a specialized pathogen of a specific host species (e.g. Triticum aestivum, wheat). A physiological race is a grouping within a forma specialis that can only infect certain host genotype(s). What is the gene-for-gene theory and understand that it applies to the rank of race. How is this concept applied to the breeding of resistant plants? 4. Some rusts are macrocyclic (like wheat stem rust), others are demicyclic and lack a uredinial stage, others are microcyclic and have teliospores as the only dikaryotic spore. Sketch out life cycles for wheat stem rust, a microcyclic rust, and a demicyclic rust, figuring out how they are going to infect the plant, reproduce and overwinter in a cold climate. Keywords: Teliospore, promycelium,, haustoria, spermagonia, spermatia, aeciospores, aecia, primary host, urediniospores, uredinia, telia, sori (sorus is singular), heteroecious, autoecious, forma specialis, gene-forgene theory, host specificity, host range, race, cultivar, macrocyclic.