COLUMBIA, MISSOURI
University of Missouri
Fluoroindole resistance of orange pericarp
--Allen D. Wright
Orange pericarp (orp1 orp2)
accumulates indole (Wright, MNL 63:61, 1989), probably due to its inability
to make tryptophan from indole. If this is the case, the mutant should
be more resistant to indole analogs than its normal sibs. Normal plants
are able to convert the less toxic 5-fluoroindole into the more toxic 5-fluorotryptophan
(Widholm, Plant Physiol. 67:1101, 1981). The mutant, being unable to do
so, should not be affected. Thus, mutant plants and normal sibs were grown
for 12 days in 5 inch clay pots (1 plant/pot) containing moist gravel then
given 0, 0.05 or 0.10 mM 5-fluoroindole in a Long Ashton nutrient solution.
The solution was given twice daily by completely flooding the pots, then
allowing to drain. The effect of fluoroindole was visually discernible
in the normal, but not mutant plants as early as 7 days after the treatments
were imposed. Plants were harvested for dry matter 14 days after imposition
of the treatment. The fluoroindole effect on dry matter was evident in
the normal sib, but no effect was discernible in the mutant. The data are
consistent with what may be expected of a mutant defective in tryptophan
synthase (B subunit) activity.
| |
|
Dry weight
|
| Phenotype |
mM 5-fluoroindole
|
(mg/plant ± SE, n=5)
|
(% of control)
|
| Normal |
0.00
|
522 ± 70
|
100
|
| Normal |
0.05
|
384 ± 54
|
73
|
| Normal |
0.10
|
315 ± 22
|
60
|
| orp |
0.00
|
117 ± 30
|
100
|
| orp |
0.05
|
126 ± 27
|
107
|
| orp |
0.10
|
113 ± 23
|
97
|
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