Genic and genotypic frequencies of endosperm mutants in maize populations under natural selection

The genic and genotypic frequencies of four maize endosperm mutants, opaque 2 (o2), shrunken 2 (sh2), sugary (su), and waxy (wx), which alter protein, sugar, soluble polysaccharides, and starchy fractions, respectively, were monitored through-out five successive generations in synthetic populations of the same genetic background under natural selection. The effect of selection was studied in the vegetative and reproductive phases through the comparison of the recessive homozygous frequencies in the seeds and in the adult plants. Data showed that natural selection acted diversely, in direction and intensity, on the mutants and in the phases of the plant life cycle. The genic frequencies indicated the occurrence of stabilizing selection over o2 and wx, and directional selection against sh2 and su