High-quality protein maize with normal genotype: changes in endosperm protein pattern

Earlier (MNL 52:37, 1978) it was reported that from the progenies of crosses between high-quality protein floury-a line and normal inbreds it was possible to isolate maizes with normal endosperm phenotype and genotype with high-quality protein. The kernels of the high lysine maizes with "normal genotype" have normal phenotype because their endosperms are vitreous and translucent, and are of the red flint type. The maizes also have "normal genotype" for they do not carry in their genetic background any floury mutant.

From ears selected with high lysine-tryptophan levels, the endosperm proteins were fractioned according to the Landry-Moureaux method and compared with normal inbreds; we found the following results:

Table 1. Endosperm protein pattern of normal inbred (DY) and high lysine "normal genotype" inbred (AL24). SS--saline (albumins, globulins); Z--zein; G1--glutelin-a; G2--glutelin-2; G3--glutelin-3.
 
 
Soluble nitrogen (percent of total)
Fraction DY AL24
SS 6.8 12.2
Z 51.7 35.7
G1 13.9 16.4
G2 12.5 9.9
G3 11.1 23.9
protein % 12.9 8.3
lysine (g/16g N) 1.9 3.5

If it is kept in mind that the primary effect of known mutants which condition high lysine is to repress the zein synthesis and to stimulate albumins, globulins and glutelin-3 synthesis, it was to be expected that the high lysine level of the "normal genotype" maizes would also be a consequence of the same phenomenon. In effect, high lysine and tryptophan levels are the consequence of a profound modification of the protein pattern compared with those of normal lines. Thus, these results suggest that the "normal genotype" represses the zein and stimulates the accumulation of saline fraction (albumins, globulins) and glutelin-3.

Recently we have obtained uniform inbred strains for the high lysine character. These lines were crossed with normal inbreds in order to establish the inheritance of this character.

Jorge Luis Magoja and Angel Alberto Nivio


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