Hormesis with Herbcides: Glyphosate as a Case Study Stephen O. Duke, Joanna Bajsa, Scott R. Baerson Natural Products Utilization Research Unit, Agricultural Research Service, United States Department of Agriculture, University, MS, USA Nina Cedergreen Univ. Copenhagen, Tåstrup, Denmark Edivaldo Velini Univ. São Paulo State, Botucatu, Brazil
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Hormesis with Herbcides: Glyphosate as a Case Study Stephen O. Duke, Joanna Bajsa, Scott R. Baerson Natural Products Utilization Research Unit, Agricultural.
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Hormesis with Herbcides:Glyphosate as a Case Study
Stephen O. Duke, Joanna Bajsa, Scott R. BaersonNatural Products Utilization Research Unit, Agricultural Research
Service, United States Department of Agriculture, University, MS, USA
Nina CedergreenUniv. Copenhagen, Tåstrup, Denmark
Edivaldo VeliniUniv. São Paulo State, Botucatu, Brazil
Solvent control was 1% DMSO (by vol)
Naptalam5-27-2004
log concentration (M)
0.001 0.01 0.1 1 10 100 1000 10000
Lem
na g
row
th (
%)
0
100
200
300
400
500
600
700
Day 5 Day 7
Effects of naptalam on L. paucicostata growth
Inhibits auxin translocation
OH
O
O
N
Scopoletin D11-9-01
Concentration (M)
0.1 1 10 100 1000 10000
Lem
na g
row
th (
% in
7 d
ays)
0
100
200
300
400
500
600
O
O
OHO
Effects of scopoletin on L. paucicostata growth
Unknown mode of action
N-phosphonomethylglycine (glyphosate)
Simple zwitterionic amino acid
First synthesized in 1950 by Henri Martin (Cilag Co.) for unknown purposes
First tested for herbicidal activity by Monsanto Agric. Products in 1970.
O
P
HO
N
OH
O OHH+
_
Highly translocatable
Co-translocates with sucrose to metabolic sinks (i.e., meristems).
Gougler and Geiger, Plant Physiol. 68: 668 (1981)
Glyphosate (kg ae/ha)
0.001 0.01 0.1 1 10 100Sho
ot d
ry w
eigh
t (%
of
nont
reat
ed c
ontr
ol)
0
20
40
60
80
100
120
Non-GR HBKC 5025GR Asgrow 4603
~ 50 X resistance factor
Nandula et al., J. Agric. Food Chem. – in press (2007)