Protein quality of induced high lysine mutants in barley

Evidence of high-lysine gene sources in barley derived from spontaneous and induced mutations has been presented. In addition barley sources considered to be "normal" also differ in lysine content. Changes in lysine concentrations invariable results in changes in other amino acids in barley protein. Protein fractions are altered in several mutant barleys and differ also in so called "normal barleys". The fractions in the normal barleys are probably more dependent upon environmental conditions than in mutant barleys. It is clearly demonstrated with chemical analyses and biological experiments with rats, poultry and pigs that high-lysine cultivars are superior in nutritive quality than their low-lysine isotypes. However, it appears that most of the lysine genotypes possess reduced grain weight and lower grain yield. This is of course unfortunate as an adequate supply of food appears to be the number one nutritional priority in the world today. This does not mean, however, that protein improvement would be of no practical value under conditions of marginal energy deprivation. The literature reviewed suggests that protein improvement would likely be of value under these conditions.