48
Richard H. Shimabukuro et al.
The fonnation of simple and complex glucosides and other glycosides is
a major mechanism for pesticide metabolism and detoxication in plants. Glucose
metabolites are involved in the bioregulation of pesticide availability in plants
and may act also as intennediates in the fonnation of tenninal pesticide residues.
2.3.4.2. Amino Acid Conjugation
Pesticides that are known to fonn amino acid conjugates through an aamide bond in plants have been predominantly acidic herbicides (Mumma and
Hamilton, 1976). The most extensive work on amino acid conjugation has been
reported for 2,4-D, IAA, and auxinlike plant growth regulators (Mumma and
Hamilton, 1976).
The amino acid conjugates of 2,4-D, IAA, and 2,4,5-T have been characterized primarily from callus cultures (Arjmand et al., 1978; Feung et al.,
1971, 1975, 1976), but similar metabolites of 2,4-D and IAA have been detected
in plant tissues (Fig. 2.21) (Andreae and Good, 1955; Loos, 1975). The major
metabolite of 2,4-D in bean plants was the ~-glucoside of 4-0H-2,5-D (Fig. 2.2)
(Hamilton et al., 1971). The amino acid conjugates were not characterized in
bean plants, but only trace amounts of these ether-soluble conjugates may have
been fonned (Hamilton et al., 1971). In plant callus culture, large amounts of
amino acid conjugates were fonned. These conjugates ranged from 84% of the
14C from [14C]-2,4-D in susceptible carrot callus tissue to 26% in resistant corn
callus tissue (Feung et al., 1975). Callus tissues of carrots, jackbeans, sunflowers, tobacco, and corn all fonned 2,4-D conjugates of glutamic (2,4-D-Glu) and
aspartic (2,4-D-Asp) acids with 2,4-D-Glu predominating (Fig. 2.21) (Feung et
al., 1975).
o
COOH
II H I
r¢r
o-C~~-COOH
6-CH~-C-N-~:2
------~.CH
I 2
CI
CI
COOH
2,4-0
IAA
2,4-0-Glu
R H
~CH2-C-N-CHZ-COOH
H
IAA-Gly
Figure 2.21. Amino acid conjugates of 2,4-D and IAA in plant callus tissue.
Richard H. Shimabukuro et al.
The fonnation of simple and complex glucosides and other glycosides is
a major mechanism for pesticide metabolism and detoxication in plants. Glucose
metabolites are involved in the bioregulation of pesticide availability in plants
and may act also as intennediates in the fonnation of tenninal pesticide residues.
2.3.4.2. Amino Acid Conjugation
Pesticides that are known to fonn amino acid conjugates through an aamide bond in plants have been predominantly acidic herbicides (Mumma and
Hamilton, 1976). The most extensive work on amino acid conjugation has been
reported for 2,4-D, IAA, and auxinlike plant growth regulators (Mumma and
Hamilton, 1976).
The amino acid conjugates of 2,4-D, IAA, and 2,4,5-T have been characterized primarily from callus cultures (Arjmand et al., 1978; Feung et al.,
1971, 1975, 1976), but similar metabolites of 2,4-D and IAA have been detected
in plant tissues (Fig. 2.21) (Andreae and Good, 1955; Loos, 1975). The major
metabolite of 2,4-D in bean plants was the ~-glucoside of 4-0H-2,5-D (Fig. 2.2)
(Hamilton et al., 1971). The amino acid conjugates were not characterized in
bean plants, but only trace amounts of these ether-soluble conjugates may have
been fonned (Hamilton et al., 1971). In plant callus culture, large amounts of
amino acid conjugates were fonned. These conjugates ranged from 84% of the
14C from [14C]-2,4-D in susceptible carrot callus tissue to 26% in resistant corn
callus tissue (Feung et al., 1975). Callus tissues of carrots, jackbeans, sunflowers, tobacco, and corn all fonned 2,4-D conjugates of glutamic (2,4-D-Glu) and
aspartic (2,4-D-Asp) acids with 2,4-D-Glu predominating (Fig. 2.21) (Feung et
al., 1975).
o
COOH
II H I
r¢r
o-C~~-COOH
6-CH~-C-N-~:2
------~.CH
I 2
CI
CI
COOH
2,4-0
IAA
2,4-0-Glu
R H
~CH2-C-N-CHZ-COOH
H
IAA-Gly
Figure 2.21. Amino acid conjugates of 2,4-D and IAA in plant callus tissue.