There are at least two inbred lines which contain restorer genes for all the known types of cytoplasmic male sterility. One of these is Ky21. The other is one of our New York lines, NY821LERf. In our work with S restoration, we have found that NY821LERf not only restores S steriles but that it also seems to have more than a single restorer gene. A single gene should give 50% pollen restoration in an F1 between a sterile and a restorer, and our restorer line MS64-7 does give 50% restoration with most S-types in such crosses. NY821LERf gives between 60 and 80% restoration, depending on the sterile used. With the aid of waxy translocation stocks supplied by the Maize Stock Center and by Dr. John Laughnan, we are attempting to map the restorer gene(s) for S restoration in the New York inbred.

Because of the special features of this line, a note on its origin seems warranted. NY821LERf stands for NY821, Long Ear, Restorer of Fertility. The inbred NY821 (which is sterile in most T, C, and S types) was the recurrent parent while an older inbred, NY16, was the source of fertility. NY16 was developed from the open-pollinated variety Weber Yellow Dent.

We have made F1 hybrids between stock seed of NY16 and the S-types to determine the restoration capability of the older inbred. Surprisingly, the version of NY16 which we used had only a single-gene pattern for S restoration, similar to that of MS64-7. It is possible that our own stock seed of NY16 represents a modification of that earlier inbred. We also have a stock of NY16 from Penn State, which is rather different in plant type and will be used in further tests.

P. H. Sisco, H. L. Everett and V. E. Gracen

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