Orange pericarp contains more niacin

--Allen D. Wright

Evidence exists that niacin biosynthesis in maize is via oxidative degradation of tryptophan (Tarr and Arditti, Plant Physiol. 69:553-556). The tryptophan synthase defective mutant orange pericarp would be a useful tool to test for alternative biosynthetic routes. As a preliminary test, five kernels each of orange pericarp and its normal sib from a near isogenic Mo17 15:1 ear were analyzed for niacin by Tomas Guillarte at Johns Hopkins University using a radiometric microbial assay for niacin (Guillarte, T, J. Nutr. Biochem. 2:334-336). The mutant contained more niacin than its normal sib when expressed on a per kernel basis and on a per gram basis. These results indicate that maize may be competent for niacin biosynthesis through a pathway that does not require tryptophan.
 
 
Niacin content ± SE
 
as µg/kernel
as µg/g
orp
4.78±0.23
16.29±0.62
N
3.93±0.77
12.91±2.41

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