The molecular patterns of zein and glutelin-1 obtained according to Landry-Moureaux (1970) were studied in Gaspé line, Euchlaena perennis, their reciprocal F1 and F2 and Tripsacum dactyloides. Patterns of the proteins of the defatted endosperm were obtained by polyacrylamide gel electrophoresis, using aluminum lactate buffer pH 3.1, and gels 8M in urea (see Figures 1 and 2).
If we compare the zein polypeptidic pattern of maize with perennial teosinte and Tripsacum, the latter differs from the first two in the absence of the polypeptides of greater mobility. These results coincide with those obtained by J. W. Paulis and J. S. Wall (J. Agric. Food Chem. 25:267-270, 1977) and they indicate a greater phylogenetic distance between Tripsacum and maize than between maize and teosinte. The zein pattern of Gaspé is practically equal to that of Euchlaena. This great similarity could be indicative of the high genetic affinity between them. The patterns of zein in reciprocal F1 endosperms are very similar and the most noteworthy fact is the appearance of a new polypeptide (Zp 14) which was not found in any of its parents. However, this polypeptide is found in Tripsacum. The patterns of the reciprocal F2 endosperms are equal to those of the reciprocal F1 endosperms from which they derive.
The molecular patterns of Gaspé, Euchlaena and Tripsacum show some differences for glutelin-1. However, Gaspé resembles Euchlaena far more than Tripsacum. As with zein the reciprocal F1 endosperms show differences in their patterns according to the direction of the cross. The F2 reciprocals resemble those of the F1 from which they derive; moreover a new polypeptide (Glp 13) appears, which is not found in its parents.
It may be concluded that there is a cytoplasmic influence over the molecular patterns of the storage proteins in the offspring of Gaspé and Euchlaena. We may say that the cytoplasm of Euchlaena perennis shows an influence in the expression, at a molecular level, of some of the components of the storage proteins of the grains and, probably, over other characters in the hybrids of this species with maize.
When storage protein polypeptide patterns of maize are compared between Euchlaena perennis and Tripsacum, certain differences are evident although they cannot be indicated as being greater than those existing among different types of maize (Zea mays). However, the endosperm protein patterns (ratios between different types of proteins) are very constant and characteristic of the species, and for this reason we may primarily declare that the greater differentiation between Maydeae species, as regards grain storage proteins, is more due to the action of regulatory units controlling synthesis of the different proteins than to structural units coding the molecular components. In other words, it is probable that regulatory genes rather than structural genes have been differentiated between species in the control process of protein synthesis, since the evidence presented in the current paper and by other authors suggests a reasonable similarity between the taxa at a molecular level (protein polypeptidic components) and a greater differentiation in the ratios in which the storage proteins are found, as a consequence of a different control in their synthesis regulation.
Figures 1 and 2.
Jorge Luis Magoja and Angel Alberto Nivio
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