A quantitative analysis of amino acid accumulation in developing grain of normal and Opaque-2 maizes

From previous observations concerned with the qualitative and quantitative evolution of protein groups in developing maize (Zea mays L.) grain, it may be deduced that the amount per grain of any amino acid incorporated into the proteins is linearly related to the amount of true protein in the grain. In this study, such a linear relationship is characterised quantitatively from experimental data by regressing the individual amino acid against the total protein accumulated in the developing grain of both normal (+) and opaque-2 (o2) maize. The linear least squares regression on total nitrogen content in the grain is also used for specifying the quantitative variations of any free and protein-incorporated amino acid in the grain. The slope B_j of the regression line represents the relative rate of accumulation of amino acid (j) in grain protein (or nitrogen) and its limiting content in protein (or nitrogen) of a grain which accumulates a large amount of it. B_j, which is compared to the amount of amino acid (j) present in the protein of immature grains, or of mature endosperm, or germ, is close to the amount of amino acid (j) present in the protein of mature endosperm. The same holds for the B_j value determined from opaque-2 maize and which differs from the amount of B_j determined using the normal variety for many amino acids. Using experimental data reported in the literature, a linear relationship has also been found in describing quantitative variations of amino acid in the developing grain of normal and Hiproly barley.