The falcifolia syndrome of Oenothera: IV. Loss of falcifolia-determining factors

Summary Inheritance of the falcifolia syndrome is explained by the hypothesis that this developmental disturbance is caused by the interaction of a non-chromosomal determinant (sigma) of Oenothera suaveolens with a complementary determinant (lambda) of O. lamarckiana when these two species are crossed. Localization of the determinants in the cell, the mechanism of their expression, and their molecular nature have not been established. Somatic segregation within the hybrids may lead to a separation of the two components, as suggested by the different reactions of sister plants in backcross tests and on selfing. The present paper presents results showing that in rare cases the fal determinants may be eliminated from the hybrid's cytoplasm. Thus, plants are produced that are phenotypically identical with the original parental strains but in crosses react like species that lack such determinants.