A new cytoplasmic male sterile (CMS) line and restorer for cotton based on the cytoplasm of Gossypium trilobum (D(8)) was reported to the Improvement Conference in 1992(1). Additional observations on the genetics of restoration confirm and strengthen the earlier observations. Namely, the D8 restorer fully restores fertility to the CMS in the F1. However, upon self-pollination of the F1, nearly all the F2 progeny are fertile (98%). The sterile plants may have resulted from incidental stray pollen from B lines. When heterozygous restored plants where used as pollen donors, 95% of the F2 progeny were fertile. When heterozygous restored plants were crossed as female with a B line, a cumulative ratio of 1:1 sterile:fertile was obtained; however, different tests had widely different ratios. For practical purposes, the restorer does not segregate through the pollen but does segregate through the female. The D8 restorer gene does not restore fertility to CMS lines containing the G. harknessii (D2) cytoplasm. On the other hand, a D2 restorer line (91080) obtained from Dick Davis (New Mexico State Univ.) fully restored the D8 conditioned CMS. The D2 restorers in the hybrid segregated in the F2 generation.

Reference

1. Stewart, J. McD. 1992. A new cytoplasmic male sterile and restorer for cotton. Proc. Beltwide Cotton Conf., p. 610.