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A cross between a male-sterile plant with 20"+t1t''' 4D carrying Ms on the whole chromosome 4D and CS produced a ratio of 1 fertile recombinant to 1 sterile non-recombinant with 21" (P < 0.50) and 1 sterile recombinants to 1 fertile non-recombinants with 20"+t1t''' (P< 0.50), indicating that the Ms gene segregated independently of the centromere on 4DS. Similarly, a male-sterile plant with 20"+t1t''' 4D (carrying Ms on 4DS) from a cross with CS produced 16 sterile recombinants and 28 fertile non-recombinants with 21" (P<0.05) and 31 fertile recombinants and 41 sterile non-recombinants with 20"+t1t''' (P< 0.25), indicating that the female gametes carrying maternal telosome 4DS with Ms had a functional advantage over those carrying Ms on whole chromosome 4D. In conclusion, the new Ms gene (now designated Ms4) is located in the distal portion of 4DS, where Ms2 is located 31.16 crossover units from the centromere.

The Ms genes producing dominantly inherited male sterility are rare in the higher plant species (Kaul 1988). The dominant or recessive mutants producing male sterility can be used to enhance out-crossing under natural conditions in a self-pollinating crop species such as common wheat (Sorrells and Fritz 1982).

Molecular biology techniques can be used to determine whether a Ms mutation inactivated a diplodized fertility gene or activated a silent gene from the diploid progenitor in the polypIoid wheat. Also, the dosage effects and inheritance patterns of the Ms and other mutants indicate the degree to which certain genes from the diploid progenitors have been diplodized by natural selection after the formation of common wheat (Sears 1972).


References

Driscoll CJ (1977) Registration of cornerstone male-sterile wheat germplasm. Crop Sci 17: 190.

Deng JY and Huang YY (1988) A dominant male-sterile mutant in common wheat: Taigu genetic male-sterile wheat (T. aestivum L). Proc 7th Int Wheat Genet Symp, Cambridge: 1077-1079.

Franckowiak JD, Maan SS and Williams ND (1976) A proposal for hybrid wheat utilizing Aegilops squarrosa L. cytoplasm. Crop Sci 16: 725-728.

Kaul MLH (1988) Male sterility in higher plants. Springer-Verlag, Berlin.

Liu BH and Deng JY (1986a) Genome study and telosomic analysis of the single dominant male-sterile Tal gene in common wheat. Scientia Seniea (Series B) 29: 516-526.

Liu BH and Deng JY (1986b) A dominant gene for male sterility in wheat. Plant Breed 97: 204-209.

Maan SS and Williams ND (1984) An EMS induced dominant allele for male-sterility transferred to euplasmic wheat. Crop Sci 24: 851-2.

Maan SS, Carlson KM, Williams ND and Yang T (1987) Chromosomal arm location and gene centromere distance of a dominant gene for male sterility in wheat. Crop Sci 27: 494-500.

Sasakuma T, Maan SS and Williams ND (1978) EMS-induced male sterility in euplasmic and alloplasmic common wheat. Crop Sci 18: 850-853.

Sears ER (1954) The aneuploids of common wheat. Mo Agric Expt Stn Res Bull 572.

Sears ER (1963) Nullisomic-tetrasomic combinations in hexaploid wheat. In: R Riley and KR Lewis (ed) Chromosome manipulations and plant genetics. Oliver and Boyd, London: 29-45.

Sears ER (1972) The nature of mutations in hexaploid wheat. Synm Biol Hung 23: 73-82.

Sorrells ME and Fritz SE (1982) Application of a dominant male-sterile allele to the improvement of self-pollinated crops. Crop Sci 22: 1033-1035.

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