nutrient supply, below ground processes and elevated co2 change the nutritional quality of...
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CCRSPI Feb 2011 Plant theme
Nutrient supply, below ground processes and elevated CO2 change the nutritional quality of cyanogenic clover Trifolium repens
Ros Gleadow
Siobhan Isherwood, Tim Cavagnaro, Saman Seneweera, Rebecca Miller,
2/20
Factors affecting food security
Production• Yield• Area• Agronomy
Nutrition• Safety• Value
Availability• Distribution• Cost• Wealth
Change in precipitation
Change in temperature
IPCC WG1
3/20
How will climate change affect nutritional value?
1. Yield 2. Nutritional value 3. Availability
4/20
Why clover? 1. Interesting roots
Mycorrhizae – P uptakeLegume – N fixing
VAM
Access to nutrients may facilitate positive response to CO2
5/20
Why clover? 2. Cyanogenic glycosides
Gleadow& Woodrow 2002, J Chem Ecol, 28, 1297.
OH
O
O
HOCH2
CH3CH3
CNHO
glucose
HCN + ketone
Chewing releases -glucosidase(detonator)
Binds to cytochrome oxidase
Linamarin (valine)Lotaustralin (isoleucine)
6/20
Why clover?3. Model for other important cyanogenic crops
Gleadow, Conn et al, 2008 Phytochem, 69: 1870Jones 1998 Phytochem 47: 155; Miller et al. 2006 Ann Bot 97: 1017.
5-10% of all plants cyanogenic60% crop plants (some parts)
Forage sorghum Cassava/Manioc
Photo: Julie Cliff, UEM, Moz Photo: Peter Stuart, Pac Seeds, Qld
7/20
IF Less protein required for photosynthesis at high CO2
THEN resources may be diverted to defence
Ru
bis
co (
% o
f co
ntr
ol)
0
20
40
60
80
100
120
350 700
CO2 ppm
Leaf protein, Rice Gleadow and Woodrow 1999, Plants in Action – available www.plantsci.org.au/publications/
Rubisco
Other
Cyanide
Is “excess” N used to synthesise cyanide?
8/20
More Nitrogen allocated to cyanide at high-CO2
~ 800 ppm CO2
~400 ppm CO220
10
0High NitrogenLow Nitrogen
CN
-N p
er N
%
AE
EA
Sugar gumsNatimuk Road, Horsham
Gleadow et al. 1998, Plant Cell Environ, 12:21
9/20
CO2 effects on cyanogenesis in clover
• FACE• Pot trials (ANU)• Nutrient trials –N, P, microbes
Siobhan Isherwood
CassavaFACE
10/20
Clover Biomass 6 months after sowing (Dec)
October 2010, 3 months
Bio
mas
s g/
m2
400
300
200
100
380 ppm 550 ppm
11/20
Cyanide in clover trending higher at 550 ppm
Cya
nide
mg/
g dr
y w
t
• Is leaf protein lower?• Nodulation rates: 6% higher significant??• Mycorrhizae colonisation: 5% higher ns?
1000
800
600
400
380 ppm 550 ppm
200
12/20
ANU study: More cyanide relative protein at elevated CO2…ONLY with +P
-N-P -N+P +N+P0
2
4
6
8
10
12
Cya
nid
e : p
rote
in
370 ppm700 ppm
Gleadow et al. 2009 J Chem. Ecol 35, 476Edwards & Evans 2005 Global Change Biol.11, 1968
13/20
Nutrient cyanogenesis trials
• N15/N14 isotopes– P improved N fixation– Fixed N used to make HCN
High P: 0.125g/kgLow P: 0.025g/kg
High N: 8mMLow N: 2mM
HP:HN HP:LN LP:HN LP:LN0.0
0.2
0.4
0.6
0.8
1.0
1.2
Nutrient Treatment
CN-N/N%
Isherwood, 2010 HONS THESIS
14/20
Conclusion: nutritional value IS affected by eCO2
• Leaf composition– Less leaf protein– Increased cyanide, relative to protein– Increase tannins, phenolics
• Soil environment is crucial
• Microbes important in nutrient acquisition…How will elevated CO2 affect these symbioses???
VIEWPOINT:Cavagnaro, Gleadow, Miller (2011) Functional Plant Biology 38, 87–96
15/20
Collaborators University of Copenhagen
Birger MøllerKirsten Jørgensen, Morten Møldrup
RSB (ANU)John Evans, Stephanie McCaffreyHoward Bradbury, Bill Foley
Pacific SeedsPeter Stuart, Wayne Chesser
Mozambique/South AfricaJulie Cliff UEMAnabela Zacarias, IIAMSimon Adams (Monash)
University of Melbourne Saman Sereweena (AGFACE)
Ian Woodrow, Jennifer Fox
DPI: AGFACE
Monash Cyanogenesis GroupCecilia BlomstedtTim CavagnaroRebecca MillerAlan NealeJohn HamillAnna BurnsNatalie O’DonnellCara GriffithsSam FromholdMelissa BainSiobhan IsherwoodKiara O’Gorman
FUNDINGARC LinkageAusAIDFinkel FoundationMonash UniversityCasstechPacific Seeds
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