The holistic approach

1
The holistic approach
in allelopathy research
Fate and toxicity of allelochemicals (natural
plant
toxins) in relation to environment and consumer
QLK5-CT-2001-01967)
(FATEALLCHEM,
A Oliveros-Bastidas, A M Simonet, J Fritz, D
Barceló, E Eljarrat, L Bonnington, M Guillamon, M
Villagrasa, A Taberner, O Sakaliene, B B
Mogensen, T Krongaard, W Oleszek, J Kus, S
Martyniuk, A Stochmal
I S Fomsgaard, L M Hansen, P Kudsk, S
Mathiassen, A M Mortensen, M Gents, A
Understrup, S T Nielsen, S S Krogh, S Mensz, C
Christophersen, E Benfenati, E Lo Piparo, F
Fratev, S Blümel, T Coja, J Idinger, FA Macías, D
Chinchilla, D Marín, J M G Molinillo,
Output
Output
Why?
Allelopathy has received new attention in modern
research. Targeted use of the allelopathic
properties of plants could lead to a reduction of
the use of synthetic pesticides. However, modern
analytical techniques and a holistic approach is
needed for a thorough evaluation of exploitation
strategies.

• Toxicological effects, Folsomia candida
• Lethal effects APO, HPAA, AAPOgtAMPO,
  AAMPOgtDIMBOAgtMBOAgtBOA
• Sublethal effects AMPO, AAMPOgtAPO, AAPO,
  HPAAgtDIMBOAgtMBOAgtBOA
• Toxicological effects, Poecilus cupreus
• Lethal effects APO, HPAA, AAPOgtBOA. No lethal
  effects AMPO, AAMPO, DIMBOA, MBOA.
• Sublethal effects None
• General conclusions maximum concentrations of
  the allelochemicals supposed to be present in the
  soil under field conditions did not pose an
  unacceptable risk to the tested standard soil
  arthropods

• Variations in levels of benzoxazinoids in plants
• between varieties (Stakado, Ritmo and Astron)
  highest level in Stakado
• between farming systems (but not consistent)
• between growth stages (highest concentration in
  young plants)
• between root and foliage (see Figure 1)
• Figure 1. Distribution in of allelochemical
  compounds
• between foliage and root.

Output
Aim?

• to perform an environmental and human risk
  assessment of exploiting the allelopathic
  properties of wheat in modern farming
• and
• to develop a framework for future assessments of
  allelopathic crops.

• Suppessive effects on fungi, ID50 (µg/ml)
• Cephalosporium gramineum
• APO 0.58 AAPO 4.57 AP 1.4 µg/ml______HPAA,
  AAMPO, HMPMA, HPMA, HMBOA no effects
• Gaumannomyces graminis var tritici
• APO 0.78 AAPO 2.18 AP 0.80 µg/ml_____ HPAA,
  AAMPO, HMPMA, HPMA, HMBOA no effects
• Fusarium culmorum no effects

Growth stage (BBCH)
Output
Views and prospects
How?

• How can we exploit the allelopathic properties of
  cereals?
• Using rye or wheat as catch crops in vegetable
  production
• Optimizing sowing time
• Optimizing choice of variety of cereal
• Breeding for wheat and rye varieties with higher
  concentrations
• Search for varieties with optimal combination
  between content of benzoxazinoids and other
  allelochemicals
• Producing benzoxazinoid derivatives as new lead
  molecules
• What is needed for assessment of extensive use of
  allelopathic crops?
• Validated sensitive analytical methods
• Considerations of relevant concentration levels
• Studies on soil processes
• Toxicological evaluations (environment, humans)
• Effect studies on weeds, crops, fungi and pests
• Studies on isolated compounds, mixtures as well
  as natural systems
• Molecular modelling (QSAR)

• Suppressive effects (pure compounds) on weeds
  and crops
• Most affectedRoot lengthgtshoot
  lengthgtgermination
• Most active
• APO (soil metabolite)
• Synthetic derivatives
• DIMBOA and DIBOA (note DT50 lt1 day)
• Figure 4.Effect of benzoxazinoid metabolites on
  root length of wild oat compared to the
  commercial herbicide Logran

• Isolation and synthesis of compounds
• Development of sensitive, intercalibrated
  analytical methods in LC-MS
• Determination of levels of benzoxazinoids in
  wheat varieties grown in different conditions
• Suppressive effects on weeds, crops, fungi and
  pests
• Fate and ecotox studies studies
• Toxicology evaluation for humans and mammals
• QSAR modelling
• Economic evaluation

Output

• Leaching from plants
• Figure 2. Leaching of benzoxazinoids from
  soil-incorporated wheat (Stakado). DT50 for
  Benzoxazinoids lt2 days
• Transformation in soil

Output

• Inhibition of pests
• Only half of the parasitic wasps will hatch on
  aphids who lived on a diet including 0.2 mM MBOA
• Increasing concentrations of MBOA in artificial
  diets results in a decrease in intrinsic rate of
  increase of aphids
• The concentration of MBOA in Stakado, Ritmo and
  Astron is not high enough for showing a
  significant inhibition of aphid growth rate
• Other properties of wheat varieties lead to
  significant differences in rate of increase of
  aphids in late growth stages of the plants

Thanks

• To the European Commission (Quality of Life,
  Framework 5) for financial support
• To our scientific officer, Mrs. Elzbieta
  Ceglarska, for valuable discussions

Danish Insitute of Agricultural Sciences,
Research Centre Flakkebjerg, DK-4200 Slagelse,
Denmark This poster only presents selected
results. Additional information
www.fateallchem.dk Inge.Fomsgaard_at_agrsci.dk