1. Cytoplasmic sterility in corn.

Pollen sterility resulting frcm a transmissible condition in the cytoplasm has been reported to occur in corn from several widely different sources. The material described by Rhoades (1933) obtained from collections by Emerson and Richey in North America has apparently been lost. The material that we received from the U.S. Department of Agriculture in 1944 and understood was the Rhoades stock, we have later learned originated in teopod crossed by a linkage tester letter received fran Dr. M.T. Jenkins). In the middle thirties Dr. P.C. Mangelsdorf, at the Texas Agricultural Experiment Station found male sterile plants in Mexican June and in its derivatives, Golden June and Honey June, which later proved to be cytoplasmic. Gird (1939) has described cytoplasmic sterile types in corn from Argentina and Brieger from Brazil. Josephson and Jenkins (1948) listed several inbreds that are fertile but produce partially sterile hybrids. The U.S. Department of Agriculture, Texas and Brazilian sources have been compared in the same inbreds after backcrossing. The Texas sterile seems to be more completely sterile than the other two sources, although the inbreds have not been completely converted to type in each case.

Restored pollen fertility resulting from gene action has been maintained during three generations of self‑fertilization. In this material cytoplasmic sterility segregates as a gene‑controlled, recessive character and would be considered to be entirely nuclear until crossed with plants that do not have pollen‑restoring genes. This may account for the "scatter grain" sterility shown by hybrids produccd from self‑fertile inbreds.