Improvement of wheat protein quality and quantity by breeding.

Substantial genetic, variability for grain protein content in wheat has been identified. In appropriate combinations known genes can increase protein content of wheat grain by 5 percentage points. Productive high protein experimental lines with good agronomic traits and satisfactory processing attributes have been identified. A high protein hard red winter variety developed in Nebraska was released for commercial production in 1975 under the name "Lancota". The high protein of Lancota resides entirely in the starchy endosperm portion of the kernel and is fully transmissible to white milled flour. The high protein of Lancota results from elevated NO3 reductase activity, increased N-absorption by the roots, and more complete translocation of N to the grain. Despite strong environmental influence on wheat protein level, genes for high protein have been demonstrated to effectively increase protein content in many different production environments. Lysine % of protein decreases but lysine % of grain increases as protein is increased. Genetic variability for lysine of sufficient magnitude to overcome the normal depression of lysine % of protein as protein is increased has been uncovered. Experimental lines have been developed in the ARS-Nebraska program in which genes for high protein and high lysine were combined. The lines have been widely distributed for use in other breeding programs.

Comparative protein quality as measured by human and small animal bioassays of three lines of winter wheat.

Incomplete information on factors contributing to apparent protein quality and to value of food products as sources of protein and how these factors interact necessitate the use of bioassay procedures. Ideally bioassay procedures should be done using the animal species for which the protein is intended. Practical considerations dictate the use of small animal bioassay rather than human bioassays for routine use in protein product evaluation. To be of real value for routine use in protein product evaluation. To be of real value for assays of food products designed for human use, animal bioassays must accurately predict human performance. Surprisingly little information is available on this topic. In the current project three Nebraska winter wheats of similar genetic backgrounds were evaluated for protein value and for value of the wheats as sources of proteins. Chemical, weanling mouse, adult human and growing human bioassay techniques were employed. Rankings of the grains were similar regardless of species used for protein quality evaluations. Similar rankings were found regardless of species used for protein quality/quantity evaluations. However, ranking varied between methods designed to evaluate protein quality and those designed to measure protein quality/quantity interrelationships. The results stress the importance of matching appropriate methodology with information desired. In a latter project, wheats of dissimilar genetic background were not as uniformily evaluated. This suggests that other factors known to affect protein quality and value were more variable in these wheats.