THE GENETICS OF SELF-INCOMPATIBILITY IN OENOTHERA ORGANENSIS

Abstract

ENOTHERA organensis is endemic to the Organ Mountains of 0 southern New Mexico where the entire population apparently con-sists of considerably less than one thousand individuak2 The morphol-ogy of the seeds indicates a relationship to members of the subgenus Oenothera (sometimes called Onagra), but the growth habit and ovule placentation resemble types belonging to the subgenus Raimannia (the Euoenothera of Engler and Prantl). Oenothera organensis has proved com-pletely cross-sterile with five species of Raimannia. Hybrids with Oeno-thera species are obtained infrequently, and are almost completely sterile, resembling Oenothera-Raimannia hybrids. Oenothera organensis differs from both these subgenera in being completely self-sterile. The inheritance of self-incompatibilty in Oe. organensis proved to be of the Nicotiana type, governed by a series of multiple allelomorphs. Interest attaches not so much to the mode of inheritance as to the methods by which genetic analyses can be followed in this material. MATERIAL Seeds of Oenothera organensis were collected at Modoc Waterfall, at the mouth of Filmore Canyon on the western slope of the Organ Moun-tains by Dr. E. W. ERLANSON and Dr. A. E. ARCHER in November, 1928. Plants from these seeds were grown in Pasadena in 1929, 1930 and 1931, and were continued from a single open-pollinated capsule from one of these 1931 plants. The culture grown in 1934 from these 1931 seeds was the first to be tested for self-and cross-incompatibility. Ten plants tested proved to be self-sterile. Nine of these plants were pollinated by a tenth, eight being cross-fertile and one cross-sterile. The first experiments to be reported were made on the progenies of these cross-fertile combinations. In 1935, Professor P. A. MUNZ collected seeds from plants growing in the type locality, Dripping Springs, in the next canyon south of Filmore Canyon. Professor R. E. CLELAND grew plants from these seeds in Balti-Oenothera organensis Munz n. nom. Oe. macrosiphon Woot. & Standl., Contr. U. S. Nat.