PLP 150C1 1st Edition Lecture 3Outline of Last Lecture I. More fungal characteristicsII. Fungus of the dayIII. Spore productionIV. Where they liveV. Fungal diagnosticsOutline of Current Lecture I. Two common fungal characteristicsII. Disease & pathogensA. Botrytis cinereaIII. SymbiosisA. Commensalism, Mutualism & ParasitismIV. Biotrophs & Semi-biotrophsV. Damping-ofCurrent LectureFungi are more commonly known for 2 characteristics• 1. We can eat them (this is what humans first learned)• 2. They can eat our crops (this is where the science of Mycology started)◦ World-wide we lose more than half of what we plant to diseases and insects◦ Pre-harvest diseases and post-harvest diseases▪ There are plant pathogens in all fungal groupsDisease: The process in which a disease-causing agent interferes with one or more essential plant functions. When the normal physiology is disrupted.Pathogen: An organism that causes diseasePathogenicity: The ability of those pathogens to interfereDo all pathogens because disease?• Disease may have definitions within a social context• Some pathogens may increase economic value of a product. Ex) Tulip breaking virus. The flowers became mosaic-looking. • Some parasites can be pathogens at one time, and beneficial at another◦ Botrytis cinerea - serious disease on grapes, but then makes a fine wine. First it’s a “bunch rot”, then it’s a “noble rot”, when value is added.Symbiosis: living with, living together. Not necessarily “happily”.• Commensalism - one benefits, the other is unafected. Ex) Walking stick on a tree• Mutualism - both benefit. Ex) Oxbird on water bufalo• Parasitism - one benefits, detriment for the other. Ex) fleas and ticks◦ Herbivores and predators aren’t included in symbiosis◦ But perhaps all of life is symbioticMicrobial infections can be mutualistic or parasitic• Rhizobium japonicum is a nitrogen-fixing bacterium. Invades plant root, makes nodules on theroot, but is also fixing nitrogen and the plant likes it.• Xylella fastidiosa is pathogenicPathogens are disease-causing• Obligate parasites can only live on living tissue, so they’re called biotrophs• Non-obligate survive in living or dead tissue, so are called semi-biotrophs• Saprobes are non-parasites, and they get food from non-living organism matter◦ A pathogen can be a parasite or a sabprobeBiotrophs don’t kill plant cells at first. When the host dies, it dies too. It gets nutrition from cells via a structure called haustorium. All groups of fungal-like organisms contain pathogens *Oomycetes were once thought to be fungi. They’re the water molds and downy mildews.• More closely related to brown algae• Mycelium is coenocytic• Hypha wall is made of cellulose, like plants.Damping-off disease is a soil borne disease. Can be pre-emergence or post-emergence.• Not very host specific• Can significantly reduce yields• If plant does survive, growth is usually stunted or matures