Biology of FUNgi. Last time...

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1 Biology of FUNgi Lecture 17 Tangled destinies Who made who? Last time... Psilocybes (and other mind altering fungi) may have influenced human evolution. Phytophthora infestans - its influence on Irish and American history as well as on outcomes of WW I. Penicillium and its impact on the WWII. 1

2 Daily trivia Did you know that AC/DC featured a sound track Who made who for a 1986 Stephen King movie Maximum Overdrive? What does that have to do with this class? Fungi Plants Environment 2

3 Fungi of the day - Taxonomy: Phylum (subphylum) Ascomycota Order - tales Family - taceae ulmi and O. novo-ulmi are the causal agents of Dutch Elm Disease DED. Elm trees knocked out by DED DED has pretty much restructured the whole Eastern North American deciduous ecotype. Elms were rather common in the eastern hardwood stands; they were decimated by DED in the insect gallery of an elm Fungi of the day - Tidbits on history: An example of devastation by DED; periodic photos of the same intersection. First identified in Holland (the Netherlands) in Hardly any disease has attracted as much attention by non-experts. Devastation by DED was significant and initial culprits were searched among automobile pollution, poor soil trucked from dikes, electric wires, poison gas from WWI. None of these explanations were close to reality. 3

4 Fungi of the day - DED spreads from tree to tree resulting in a infection center similar to that of Heterobasidion Tidbits on history: First North American case of DED was detected in Ohio and several states in the east coast Possible introduction as a result of cross Atlantic commerce of garden supplies, trees or tools. The spread of DED was rapid. By 1970, DED had reached the Pacific coast. DED infection center Fungi of the day - Symptoms of DED Flagging branches Some branches show flagging. The water and nutrient supply is cut of by fungal growth in the vascular tissue. Fungus grows throughout the tree killing it. Fungus spreads to neighboring trees. Vascular colonization by Dead (DED) trees DED infection center 4

5 Fungi of the day - DED life cycle explains rapid spread: Beetle carrier Vegetative spread Spread of DED: Fungi of the day - Scotylus or Hylurgopinus beetles feed on elm bark European (Scotylus) or American (Hylurgopinus) bark beetles feed on the cambial layer of elm trees and deposit their eggs in the cambium. Deposited eggs hatch and the larvae feed in the cambial layer of the elm trees building a gallery. Bark beetle gallery in the elm tree 5

6 Spread of DED: Fungi of the day - Sporothrix budding conidia of ascospores (rarely) or conidia find their way to an elm tree (aerially to a wound, by insect vector). perithecia Once in a tree budding Sporothrix type conidia spread in the vascular tissues. New bark beetles and their larvae carry sticky conidia from synnematal Graphium and are vectors for spread to new elm trees. Graphium sticky synnematal conidia of Spread of DED: Fungi of the day - In addition to the insect vectors or random dispersal by airborne spores., like Heterobasidion will spread in the vascular systems of crafted roots. This explains the infection centers. DED infection center and root crafts 6

7 Fungi of the day - Management of DED: Elm breeding for greater resistance. Cutting crafted roots. Remove root crafts Fungicides in high-value arboreal trees. Pump fungicides into the vascular system To sum up on DED... Elms were brought from a dominant overstory tree to subcanopy shrub by DED. Whole North America was covered in <50 years. Rapid spread explained by insect vectors, sticky conidia and the vegetative spread through crafted roots. 7

8 This time... Look into fungi that restructured our landscapes. Remember Glomales, and Epichloë. SOD and Cryphonectria. Mycorrhizas controlled plant communities Klironomos and coworkers observed: 1) yield was greater if more fungi were present 2) plant community composition was, to some degree, determined by the fungi in soil And concluded: 1) Different AM fungi do different things in soil (some may be good at P, some water, other N uptake) 2) Plants respond differently to different types of AM fungi. + yield number of AM fungi + 8

9 Endophytes determined plant communities Keith Clay s experiment: 1) Diversity was higher without Epichloë and Festuca more abundant with Epichloë Explanation: With the endophyte the fescue dominated the plant communities. Without, fescue suffered from herbivory and lost its competitive edge. + Plant Diversity + Biomass Festuca Other grasses Epichloë + Epichloë + Another plant pathogen that changed the landscapes Cryphonectria parasitica - Chestnut Blight: Until the arrival of C. parasitica American chestnut was an important source of decay resistant timber and tasty chestnuts. Castanea dentata the American chestnut was the redwood of the east until early 20th century. Chestnuts were harvested for food in the eastern North America. 9

10 Another plant pathogen that changed the landscapes Cryphonectria parasitica - Chestnut Blight: American chestnuts were small but tasty. The Asian chestnuts were big but tasteless. The clever plant breeders, in their immaculate wisdom proposed a breeding program combining the best of both. In the seedlings they brought from Asia they also brought Cryphonectria, to which the Asian chestnuts were resistant. American chestnuts were puny in comparison to Asian nuts. Another plant pathogen that changed the landscapes Cryphonectria parasitica - Chestnut Blight: In 1903, the Bronx zoo keeper noticed that the chestnuts in the zoo were quickly dying. The trees had splitting bark as a result of stroma pushing through the bark and were covered by yellow mitosporic pycnidia. The death was due to phloem being destroyed by Cryphonectria. Like DED, it also plugged xylem. Pycnidia and stroma in chestnuts trees. 10

11 Another plant pathogen that changed the landscapes Cryphonectria parasitica - Chestnut Blight: The spread of Cryphonectria was comparable to that of DED. In 50 years, by 1950, chestnut blight had spread through most of Northeastern US. The extent of the disease was devastating. Historically 25% (one in four) of the trees in deciduous hardwood stands were chestnuts. They all were gone. To put a number value on the catastrophe, in 1912 alone the losses in Pennsylvania, West Virginia and North Carolina totaled 82.5 million One isolated stand remained in Wisconsin, by 1980 even that was infected. The death of chestnuts was catastrophic, and the spread of disease quick Another plant pathogen that changed the landscapes Cryphonectria parasitica - Chestnut Blight: In the process of international commerce, Cryphonectria parasitica was introduced to Europe, where it took a similar pace of spread. However, in Italy, a healing wound was discovered. The Cryphonectria isolated from that wound was not typical yellow colony, but white. When in contact with the yellow colony the white seemed to cause the yellow strains to lose their virulence as well. The death of chestnuts was catastrophic, and the spread of disease quick. 11

12 Another plant pathogen that changed the landscapes Cryphonectria parasitica - Chestnut Blight: The hypovirulence, absence of unhealable, cankers was found to be a result of double strand DNA virus (dsdna) carried in the white strain. When infected chestnuts were sprayed with the hypovirulent strain, the virus was passed on and wounds could heal. The hypovirulence seemed like a magic remedy. Unfortunately it does not seem to work as well in the US. The stand in Wisconsin was sprayed and shows little signs of recovery. The death of chestnuts was catastrophic, and the spread of disease quick. Future candidate for big trouble -SOD Sudden Oak Death - SOD: Recently (1998/1999) western California was alerted by vast number of dead/dying oaks for no apparent reason. Closer look showed some bleeding lesions in the oak bark. SOD - bleeding canker of an oak Landscapes and aerials from California and southern Oregon. 12

13 Future candidate for big trouble -SOD Sudden Oak Death - SOD: Closer look into the lesions revealed dark zone lines. The culprit was soon identified and isolated. Another species of oomycetous Phytophthora, P. ramorum had somehow been introduced to California coast and was making a rapid spread east and northwards. Black zone lines in the bleeding lesions Future candidate for big trouble -SOD Sudden Oak Death - SOD: SOD is an invasive, newly-introduced species. However, it is more problematic than DED and bears a great promise of being the plant pathogen of the century. Phytophthora ramorum is not only a pathogen of oaks, but can (and does) infect Douglas firs and redwoods among others. Phytophthora ramorum caused symptoms in Douglas fir and California coastal red woods. 13

14 Future candidate for big trouble -SOD Sudden Oak Death - SOD: The breadth of SOD host range is not known yet. However, evidence suggests that plants from different orders and families are susceptible. These include major economically important timber and ornamental taxa. Summary the - DED. Cryphonectia - Chestnut blight. Phytophthora ramorum - SOD 14