The Inheritance of a Recurring Somatic Variation in Variegated Ears of Maize

Abstract

A somatic variation in maize is shown to be inherited in simple Mendelian fashion. The variation has to do with the development of a dark red pigment (or in one stock a brown pigment) in the pericarp of the grains, often associated with the development of an apparently similar pigment in the cob and husks. Plants in which this pigment has a variegated pattern may show any amount of red pericarp, including wholly self-red ears, large or small patches of self-red grains, scattered self-red grains, grains with a single stripe of red covering from perhaps nine tenths to one tenth of the surface, grains with several prominent stripes and those with a single minute streak, ears with most of the grains prominently striped and ears that are non-colored except for a single partly colored grain, and probably also plants with wholly self-red and others with wholly colorless ears. It is shown that the amount of pigment developed in the pericarp of variegated seeds bears a definite relation to the development of color in the progeny of such seeds. This relation is not such that seeds showing say nine tenths, one half, or one tenth red will produce or even tend to produce plants whose ears as a whole or whose individual grains are, respectively, nine tenths, one half, or one tenth red. Experimental results indicate rather that the more color in the pericarp of the seeds planted the more likely are they to produce plants with wholly selfred ears, and, correspondingly, the less likely to yield plants with variegated ears. Self-red ears thus produced are shown to behave in inheritance just as if they were hybrids between self-red and variegated races or between self-red and non-red races, the behavior in any given case depending upon whether the parent variegated ears were homozygous or heterozygous for variegated pericarp and whether they were self-pollinated or crossed with white. It is suggested that these results may be interpreted by the assumption that a genetic factor for variegation, V, is changed to a self-color factor, S, in a somatic cell. All pericarp cells directly descended from this modified cell will, it is assumed, develop color, and of the gametes arising from such modified cells one half will carry the S factor and one half the V factor if only one of the two V factors of the somatic cells is changed, or all such gametes will carry S if both V factors are changed. The V factor is thought of as a sort of temporary, recessive inhibitor that sooner or later permanently loses its power to inhibit color development, becoming thereby an S factor. Or it may be that the dominant factor, S, is temporarily inactive, but sooner or later becomes permanently active. Again, the S factor may repeatedly arise de novo. The cause of any such change in factors is beyond intelligent discussion at present. The results of Correns with Mirabilis and of de Vries with Antirrhinum are shown to be subject to the same analysis as that used to interpret the results secured with maize.