S. Duangploy, M. S. Zuber and B. G. Cumbie (MGCNL 50:90-91, 1976) found that the inheritance of multiple aleurone layering is controlled by possibly two genes with partial dominance where both dominant genes are necessary. The results of the backcrosses agreed with the model proposed although their reciprocals didn't. O. E. Nelson and M. T. Chang (Crop Sci. 14:374, 1974) also found conflicting results in different F2 families.
We conducted a backcross study of linkage. The marker source was an advanced generation of the F1 of Mangelsdorf Tester crossed to IAC Maya, a mostly Yellow Tuxpeno cultivar. The source of multiple aleurone was ACRE 134, from the Brazilian Germplasm Bank, crossed and backcrossed once to IAC Maya o2 before concentrating the multiple aleurone character. Both materials aren't lines. This IAC Maya with multiple aleurone was pollinated by the marker, as was the resulting F1 hybrid. The criterion of classification was single layer (mal), and more than one layer, multiple aleurone (Mal). There was difficulty in classifying wx in su background. The results and chi-square analysis are presented in Tables 1 and 2.
Table 1. Phenotypic frequencies observed in two families of backcrosses
whose origin is described in the text.
||Y||Su||Wx||I||II||I + II|
|I + II (+)||73||167||168||222|
|I + II (-)||239||145||144||90|
Table 2. Results from both families pooled. Phenotype, frequency, and
tests for the segregations indicated. Note that with wx the marker is heterozygous.
The interactions are the exact ones; below it is the heterogeneity between
|Marker||M Mal||M mal||m Mal||m mal||Mal 1:3||Marker 1:1||Interaction||P|
Inspection of Table 1 shows at first glance that two complementary dominant genes would explain most of the inheritance of multiple aleurone layering. Note that for waxy the cross or backcross was probably made with an heterozygous marker. By Table 2 we see that there is linkage of one of the dominant complementary genes with Su for both families without heterogeneity. With Y there was no sign of linkage. With wx although the total showed strong evidence of linkage, with P < 0.01, there was also an almost equally strong heterogeneity. To see the reason for this heterogeneity Table 3 was mounted. In it we present for both families I and II, within Wx and wx separately, the segregation for Mal and Su. It is seen that in Family I within Wx there is a 1:7 segregation of Mal:mal, within wx a 1:1 segregation. In Family II the segregation in both Wx and wx remained the same, 1:3. It suggests that linked to wx in Family I there was one recessive gene complementary to the dominants that are complementary for Mal. In Table 4 is shown the calculation of p. With su and a coupling situation and the model shown by maximum likelihood the value of p obtained was 48.2 ± 5.36 (a). This value is not coherent with the significance of the chi-square interaction. To get a better fit the values of Su:su were adjusted to a perfect 1:1 segregation before calculating p, 46.2 ± 5.09 (b). The value of n to calculate the error was taken as double the su class, the smaller class. The chi-square deviations dropped sharply. With Wx and a repulsion situation the linkage was calculated for Family I only. First we multiplied by three the wx frequencies to get nearer 1:1, Wx:wx segregation. The value of p obtained 14.7 ± 7.47 (c). Adjusted to a perfect 1:1 the value was p = 14.6 ± 7.58 (d) with a little improvement in fit. The value of n to calculate the error was double the wx class. Since there are clearly at least three genes involved for multiple aleurone and we calculated the solutions for a two gene model, these are only rough approximations to show linkages and phases.
Table 3. Hierarchical analysis showing segregation within Wx and within
wx separately, for su marker gene with Mal. In Family I the 1:3 segregation
breaks down in a 1:7 within Wx and 1:1 within wx. In Family II there is
|Su Mal||Su mal||su Mal||su mal||Multiple aleurone||Marker||Exact Interaction||P|
Table 4. Phenotypes, models applied to the calculation of p for an approximate
solution of the results, frequencies observed and calculated, p and their
errors and chi-square of deviations from fitting.
1/4 ( 1+p)
|I + II|
aWith the original observations.
bCorrecting the observations for a perfect 1:1, Su:su segregation.
cMultiplying by three the wx frequencies observed.
dCorrecting the observations for a perfect 1:1, Wx:wx segregation.
Our results suggest that the multiple aleurone layering can be controlled by three genes. There is a pair of complementary dominants. Another recessive gene is complementary to these dominants in some way. One of the dominants should be loosely linked to Su; we propose for it the symbol Mal2. The recessive complementary gene is strongly linked to wx; we propose for it the symbol mal1. It seems more widespread in non-multiple aleurone maize. Not excluded is the possibility of a colored scutellum type of inheritance including inhibitors and linkages between multiple aleurone factors.
Luiz Torres de Miranda
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