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

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors

Return to the MNL 64 On-Line Index
Return to the Maize Newsletter Index
Return to the Maize Genome Database Page