Fertile Sterility Maintainer Mutants in Cytoplasmic Male Sterile Pearl Millet 1

One hundred seven natural male‐fertile mutants occurring in the A 1 and A 2 cytoplasms of cytoplasmic male sterile (cms) pearl millet, Pennisetum americanum (L.) K. Schum., were studied. Three, or perhaps four, of these arose as nuclear mutations of tile recessive r cms maintainer gene to the dominant R male fertility restorer gene. The remaining 103 appeared to be cytoplasmic mutations that changed cms A cytoplasm to the N cytoplasm that makes B lines male‐fertile cms maintainers. The B lines resulting from such mutation appear to be stable and identical to normal B lines in appearance and performance. The frequency of these male‐fertile mutants, in terms of plants affected, ranged from 1 : 431 to 1 : 737 male‐fertile mutants : cms plants. In terms of florets or seeds affected, the ratio would approximate 1 : 1,500 to 1 : 2,500. Tilt 239 A 2 , increased a number of generations without roguing, contained one male‐fertile mutant for every 48 plants. Roguing or limited generation increase from breeder cms seed will be required to prevent the deterioration of cms lines due to natural mutation.