Post on 18-Feb-2016
description
Measurement of a possible signal for nitrogen starvation in a cyanobacterium-plant symbiosis
Jeff Elhai
World Population
High yield dwarf wheat
Green Revolution
www.Isuagcenter.com
NH3NH3
Conventional wheat
N2 NH3
Fixan PE, West FB (2002) Ambio 31:169-176.
8 fold
Chemical Fertilizer Production$100's of $billions / year
Chemical production
of NH3
NASA Visible Earth http://visibleearth.nasa.gov/
Low oxygen
High oxygen
Downstream effects of fertilizer runnoff
N2 NH3
$100's of $billions / year
What to do?
Biological Fertilizer Production
N2 NH3
$100's of $billions / year
Plant Symbiont Cyanobacterial Symbiont
Nostoc punctiforme
Anthoceros (bryophyte)
Free and Clean
N2
NH3
+
Biological Fertilizer Production
N2 NH3
$100's of $billions / year
Plant Symbiont Cyanobacterial Symbiont
Nostoc punctiforme
Free and Clean
Cycads (gymnosperm)
N2
NH3
+
Biological Fertilizer Production
N2 NH3
$100's of $billions / year
Plant Symbiont Cyanobacterial Symbiont
Nostoc punctiforme
Free and Clean
Gunnera (angiosperm)
N2
NH3
+
Biological Fertilizer Production
N2 NH3
$100's of $billions / year
Cyanobacterial Symbiont
Nostoc punctiforme
Free and Clean
But not
N2
NH3
Why not crop plants?
+
How do symbiotic plants differ from others?
N2
NH3
A clue from free-living Nostoc?
Starving for Nitrogen
N2
NH3
Plenty of Nitrogen
NH3NH3
How does NH3 shut off N-fixation?
How does NH3 shut off N-fixation?
Glutamate Glutamine
N2 NH3
α-ketoglutarate
Glutamate+
AMINO ACIDS
How does NH3 shut off N-fixation?
Glutamate Glutamine
N2 NH3
α-ketoglutarate
Glutamate+
AMINO ACIDS
Glutamine
α-ketoglutarate
How does NH3 shut off N-fixation?
Glutamate Glutamine
N2 NH3
α-ketoglutarate
Glutamate+
AMINO ACIDS
Glutamine
Could plants use this to fool Nostoc?
How does NH3 shut off N-fixation?
α-ketoglutarate
Could plants use this to fool Nostoc?
Does Nostoc within plants have a high level of α-ketoglutarate?
How to measure α-ketoglutarate inside cells?
The hydromedusa Aequoria victoria
Source of GreenFluorescent Protein
(GFP)
CyanoFluorescent Protein
(CFP)
YellowFluorescent Protein
(YFP)
How to measure α-ketoglutarate inside cells?
The hydromedusa Aequoria victoria
Source of GreenFluorescent Protein
(GFP)
CyanoFluorescent Protein
(CFP)
YellowFluorescent Protein
(YFP)
How to measure α-ketoglutarate inside cells?
CFPYFP
α-ketoglutarate
How to measure α-ketoglutarate inside cells?
CFPYFP
α-ketoglutarate
α-ketoglutarate Yellow fluorescence
Blue fluorescence
How to measure α-ketoglutarate inside cells?
CFPYFP
α-ketoglutarate
α-ketoglutarate Yellow fluorescence
Blue fluorescence
How does NH3 shut off N-fixation?
α-ketoglutarate
Could plants use this to fool Nostoc?
Does Nostoc within plants have a high level of α-ketoglutarate?
How does NH3 shut off N-fixation?
α-ketoglutarate
Could crop plants do the same?
Does Nostoc within plants have a high level of α-ketoglutarate?