nutrient supply, below ground processes and elevated co2 change the nutritional quality of...

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