Submitted to: Maize Genetics Cooperation Newsletter
Publication Type: Other
Publication Acceptance Date: 1/3/2002
Publication Date: 3/15/2002
Citation: SCOTT, M.P. ANALYSIS OF KERNEL TRYPTOPHAN CONTENT IN INBRED LINES AND THEIR OPAQUE2 CONVERSIONS USING METHODS OPTIMIZED FOR MAIZE BREEDING PROGRAMS. MAIZE GENETICS COOPERATION NEWS LETTER. 2002. v. 76. p. 2. Interpretive Summary: Because so much corn is used for animal feed and human food, the nutritional quality of corn is important. Corn is deficient in the amino acid tryptophan, limiting its nutritional value. Before the level of tryptophan in corn can be increased by biotechnology or by conventional breeding, methods must be available for measuring tryptophan levels in many ysmall samples in a short time. This manuscript describes the development and optimization of methods for the analysis of tryptophan in single kernels. These methods will be useful to plant breeders interested in developing high-tryptophan corn. Tryptophan levels in inbred lines that could be useful for developing high-tryptophan corn were determined. Lines containing the opaque2 mutation, which is known to improve the nutritional quality of corn, contain varying amounts of tryptophan compared to their wild-type counterparts.
Technical Abstract: Methods for high-throughput analysis of tryptophan have been optimized for use on milligram-sized samples of maize kernels. Ba(OH)2 and pepsin hydrolysis of the sample followed by chemical detection of tryptophan in the hydrolysate were compared. Both methods gave a similar ranking of samples with varying levels of tryptophan, with enzymatic hydrolysis giving ga slightly higher measurement. Standard deviations of samples hydrolyzed with Ba(OH)2 were lower than those of samples hydrolyzed with pepsin; however, pepsin hydrolysis is more suitable to high-throughput analysis. Using these methods, the tryptophan content of five inbred lines and their opaque2 conversions were compared. The tryptophan content of the opaque2 lines varied from 99% to 176% of the level found in their corresponding recurrent parents.