The Genetics of Evening Primroses and Mice

Abstract

IN 1905, Dr. G. H. Shull, of Princeton, received from Dr. de Vries ten rosettes of Oenothera lamarckiana from the locality at Hilvershum, Holland, which had supplied the original material for the classic researches of de Vries many years before. In 1921, among the descendants of these plants appeared a colour-mutation which Shull calls old gold (vetaurea). The petals are flushed with apricot-colour, strong toward the base, fading out distally. In a very interesting and detailed paper (Genetics, May 1926, p. 201), Shull describes the behaviour of this mutant in a variety of crosses. It is recessive to the ordinary yellow flower. In order to test it further, Shull introduced into his cultures the very pale yellow mutant called ‘sulphur’ (sulphurea), and was surprised to find that-old-gold was complementary to sulphur, the two when crossed giving invariably plants with flowers of the normal yellow colour. Accordingly the normal yellow is expressed by the symbol SSVV (double dominant), the homozygous sulphur by ssVV, and the homozygous old-gold by SSvv. By suitable crosses the double recessive ssvv was obtained, and proved to be a pale flower, with the bases of the petals flushed with the apricot tint. Shull called it gold-centre (aurata). The amount of the reddish or old-gold colour is much less than in old gold.