Cytoplasmic restoration of nuclear genetic male sterility

Hermsen (1968, Euphytica Sup. No. 1:63-67), discussed a system which would utilize a nuclear gene pair for fertility vs. male sterility (Ms* vs. ms*), together with a type of cytoplasm that would restore fertility to a genotype homozygous recessive at the ms* locus. No examples were cited. One of the advantages of such a system, as discussed by Washnok (1972, MGNL 46:25-27) is that the ultimate hybrid planted by the farmer would have normal cytoplasm. The purpose of this note is to call attention to the manner in which such a system was discovered in flax. Bateson and Gairdner (1921, J. Gen. 11:269) and Gairdner (1929, J. Gen. 21:117-124) reported that crosses using a procumbent strain as female with tall strains as male had fertile F1's but segregated 3 fertile:1 male sterile in F2. Progeny of the reciprocal crosses were all fertile in F1 and F2. The explanation offered was that the tall strains were homozygous for a recessive ms* gene but had a type of cytoplasm that made them fertile; the procumbent strain had the normal Ms* gene but a type of cytoplasm which, with an ms* ms* genotype, produced a male-sterile plant. We propose the usage of (R) for the restorer cytoplasm and (r) for the non-restorer cytoplasm. The procumbent strain would be (R) ms* ms* and the tall strain (r) Ms* Ms*.

During studies of the inheritance of wilt resistance in flax, a large-seeded Crete variety behaved in a manner similar to that of the procumbent strain (Burnham, Ph.D. thesis, Univ. of Wisc.). Only by the study of reciprocal crosses carried into F2 was the system discovered in flax. A paper reporting results of crosses with the Crete variety of flax and outlining a system for using cytoplasmic restoration of nuclear genetic male sterility is in its final stages of preparation: Burnham, C. R., M. C. Albertsen, and R. L. Phillips, Cytoplasmic restoration of nuclear genetic male sterility.

For a similar test for such a system in corn, reciprocal dialleles within groups of inbreds in corn (7, 6, and 6 inbreds in each of three groups) are being checked in F2 for segregation for male sterility. F2's for all the crosses will be grown in 1978.

Charles R. Burnham

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors.

Return to the MNL 52 On-Line Index
Return to the Maize Newsletter Index
Return to the Maize Genome Database Page