WCTA Annual Meeting, Feb 26, 2007, Victoria, B.C.

www.uoguelph.ca/~thsiang/present/2007infect_wcta.htm



The Infection Process: How does disease start?

Tom Hsiang, Dept. Environmental Biology

University of Guelph, thsiang @ uoguelph.ca



Presentation Objectives

Turf pathogens & other turf pests

Fungi

Fungi make food (esp. yeasts)

Penicillium on bread

Bathroom tile & window mold

Wood -rotting fungus (Polyporus)

Wood-rotting fungus (Ganoderma)

Earth-star

Stink-horns (they stink)

Penicillium

http://www.uoguelph.ca/~gbarron/MISCELLANEOUS/penicill.htm

Penicillium spores

http://treediseases.coafes.umn.edu/image/penicillium_%20condia.jpg

Aspergillus spores http://www.astrographics.com/GalleryPrints/Display/GP2047.jpg

Aspergillus niger spores http://129.215.156.68/Images/Asexual%20structures%20of%20Aspergillus%20niger.jpg
Spore production - sporodochium

Spore production - pycnidium

Spore production - acervulus

Spore production - mushroom gill (Shearer)

Mushrooms are Basidiomycetes

Spore production - Ascomycetes

Ascospores explosively discharged
from http://www.uwyo.edu/bot4300/

Spores produced by Oomycota (e.g. Pythium)

Oomycota zoospores vs. sperm
http://classes.plantpath.wsu.edu/plp521/PlP150_files/Lecture%202%20Lifestyles%20of%20the%20Fifth%20Kingdom%20compressed%20file.ppt

Spores

1 um = 0.000001 m (a millionth of a meter)

Spore germination
http://www.phytonews.ch/powerpoint06/Talendo_f.ppt

Hypha (plural: hyphae)

Hyphal growth

Hyphal growth rate
http://helios.bto.ed.ac.uk/bto/FungalBiology/Fig3_15a.jpg Neurospora crassa FM-64 under optimum conditions

Hyphal growth

Hyphal strand next to what?

Hyphal strand next to what?

SEM of hair and hyphae http://www.astrographics.com/GalleryPrints/Display/GP2096.jpg

Spore - Hyphae - Mycelium

Hyphal strands or Mycelium?

Fungal Mycelium

Sclerotium (plural: sclerotia)

Sclerotia

Disease Cycle

Inoculation

Pre-penetration

Penetration

Penetration (looking for stomates) http://classes.plantpath.wsu.edu/plp521/PlP150_files/Lecture%202%20Lifestyles%20of%20the%20Fifth%20Kingdom%20compressed%20file.ppt
Penetration

Penetration
of the stomatal pore from an appressorim by the uredospore germling of Uromyces appendiculatus. (Mendgen et al. Ann. Rev. Phytopath. 34:367, 1996)

Penetration
The dark, wavy, vertical line in the center is an infection tube of the rust fungus, Puccinia recondita, growing toward a stomate by Gilbert Ahlstrand. http://www.ars.usda.gov/is/graphics/photos/k7778-1.htm

Penetration

Penetration

Penetration with appressoria

from http://www.uoguelph.ca/~thsiang/pubs/pdf/03cgram_cjm.pdf

Magnaporthe grisea penetration

Penetration peg

from http://classes.plantpath.wsu.edu/plp535/documents/Peever-Penetration2006.ppt

Penetration by appressorium

Anthracnose infection process

Anthracnose infection structures

see figure 14 in Chen, Goodwin & Hsiang. 2001.

http://www.uoguelph.ca/~thsiang/pubs/pdf/01cdestruct_mr.pdf

Enzymes

Penetration through cuticle
http://www.bio.uu.nl/~fytopath/Powerpoint/College%2015%20Pieterse.ppt
Intracellular Infection

Incubation

Sporulation

Anthracnose - acervulus

http://www.uoguelph.ca/~thsiang/pubs/pdf/03cgram_cjm.pdf

Anthracnose - acervuli & spores
http://www.paceturf.org/photo/showphoto.php/photo/509/sort/1/cat/1

Dissemination



Disease Control