Morphogenesis, physiology and genetics of development of fungal
fruit bodies - plus some holiday snaps
David MooreSchool of Biological Sciences
The University of Manchester
Fungal mycelium has a number of alternative developmental
pathways open to it
• continuation of hyphal growth
• production of asexual structures
• progress into the sexual cycle
These are not strict alternatives
• a culture may express all of these possibilities
• so, genetic control must be local
Classic genetic approaches are:
• identification of variant strains
• complementation tests to establish functional cistrons
• heterokaryons to determine dominance
• epistatic relationships in heterokaryons (to indicate the sequence of gene expression)
hyphal tu ftsfru it body in itials
E nvironm entalstim uli
hap-5 & hap-6
hap-7 & hap-8
hap-1
fru it bodyin itials
maturefru it body
monokaryoticfru iting
hyphalfusion
dikaryotic fru iting
genefi fb
fru it bodyin itials
m aturefru it body
genem ating typefactors
hap-2, -3 & hap-4
hyphal tu ftsfru it body in itials
E nvironm entalstim uli
hap-5 & hap-6
hap-7 & hap-8
hap-1
fru it bodyin itials
maturefru it body
monokaryoticfru iting
hyphalfusion
dikaryotic fru iting
genefi fb
fru it bodyin itials
m aturefru it body
genem ating typefactors
hap-2, -3 & hap-4
Sclerotiumin itial
I n itiation ofaggregatedgrow th
C apexpan sion
H ymenophored ifferen tiation
H ymen iumd ifferen tiation
M eiosis andsporu lationC ap
dem arcationFru it bod y
in itial
R in d p igm en tationM edu lla d ifferen tiation
Sclerotiummatu ration
Stemd ifferen tiation
Stemexpan sion
Stemdem arcation
Sclerotiumin itial
I n itiation ofaggregatedgrow th
C apexpan sion
H ymenophored ifferen tiation
H ymen iumd ifferen tiation
M eiosis andsporu lationC ap
dem arcationFru it bod y
in itial
R in d p igm en tationM edu lla d ifferen tiation
Sclerotiummatu ration
Stemd ifferen tiation
Stemexpan sion
Stemdem arcation
Normal morphogenesis is made up of developmental subroutines
• subroutines for hymenophore, hymenium, stem, cap, etc.
• subroutines can be put into operation independently of one another
• under separate genetic control
• under separate physiological control
Control of fungal morphogenesis
Molecular models which might account for these features are:
• translational triggering
• feedback fixation
Translational triggering isa mechanism which can relate morphogenesis to physiological
preparation (‘competence’), and to response to environmental
signals
Translational triggering
• illumination• temperature shock• nutritional crisis• injury• edge encounter• extracellular matrix signal• other factors
The ‘trigger’ might be caused by
Feedback fixation
• reinforces expression of the whole regulatory pathway to make it independent of the external environmental cues which initiated it
• results in developmental determination in the classic embryological sense
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