Specific relationship of storage proteins in maize and its wild relatives

The fractionation of maize endosperm proteins by means of the Landry-Moreaux technique has proven to be very useful as, for example, to establish the regulating action of the different endosperm mutants.

A single gene can modify the protein pattern as it occurs with those which repress the synthesis of zein. Not considering these mutants, it can be said that in the normal maizes the protein pattern of the endosperm is in general relatively constant, there being a reasonable similarity. As a result of what has been said, the protein pattern of the endosperm may be considered as a specific characteristic that may be used to distinguish maize from its wild relatives. This idea has been discussed before (MNL 55:62-63, 1981), where it was pointed out that the main distinction in the storage proteins among the Maydeae is far more due to the action of the regulatory genes than to structural units.

The protein fractions of the endosperm of maize (Zea mays), diploperennial teosinte (Z. diploperennis), perennial teosinte (Euchlaena perennis = Zea perennis) and tripsacum (Tripsacum dactyloides), shown in Table 1 were obtained according to the Landry-Moureaux technique. The seeds of diploperennial teosinte were provided by Julian Camara Hernandez.

As mentioned before (MNL 55:60-61, 1981), it can be stated that the protein fractions of perennial teosinte and Tripsacum distinctly differ from those of maize, because they show a low proportion of albumins and globulins (approximately one-third), a high level of glutelin-1 (approximately double) and a low proportion of glutelin-3. The patterns of perennial teosinte and Tripsacum, which happen to be similar, and distinctly different from the one of maize, are designated as protein pattern "T," and that of maize, as protein pattern "Z" (see Figure 1).

The protein pattern of Z. diploperennis has characteristics which are intermediate to those of "T" and "Z". Diploperennial teosinte has a low proportion of albumins and globulins, but it is between those of maize and perennial teosinte, a proportion of glutelin-3 similar to perennial teosinte or Tripsacum. As was mentioned before (MNL 55:60-61, 1981), the high relationship of glutelin-1 (which is characteristic of perennial teosinte) dominates in the progenies of the hybrids between this species and maize, whereas the low proportion of albumins and globulins and of glutelin-3 (also characteristic of perennial teosinte) acts as partially dominating.

From the results obtained, it can be determined that an intermediate protein pattern (TZ), as the one Z. diploperennis has, might derive from that of Z. perennis by germplasm introgression of maize, as the high ratio of G1 could only take place by successive backcrossings of the hybrids with maize. Consequently we present the hypothesis that the intermediate protein patterns (TZ), which are characteristic of Z. diploperennis according to the results of other authors as well, and of annual teosinte (Z. mexicana) can have originated by maize introgression in Z. perennis. If the protein pattern is a character which can be considered specific, it is probable that Z. mexicana and Z. diploperennis are species with Z. mays introgression; and perhaps Z. perennis is the sole species closely related to maize which is not contaminated with its germplasm, that is to say, which was early distinguished in the evolutive process of the Maydeae.

It can also be inferred that the introgression of germplasm of Z. perennis or Tripsacum into maize may give rise to tripsacoid protein patterns, which are characterized by having a low ratio of albumins and globulins and a high ratio of glutelin-1. Especially the high ratio of glutelin-1 could indicate the introgression of Tripsacum or perennial teosinte in maize, as we have found in some maizes (results not published).

Table 1.

Figure 1.

Jorge Luis Magoja and Angel Alberto Nivio


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