Cucurbit Genetics Cooperative
Other Crop Genetics Cooperatives
Home About Membership Reports Gene Lists Conferences Links Search NCSU
Cucurbit Genetics Cooperative Report 3:31 (article 17) 1980

Male Sterile-1: Stability of Expression

J. D. McCreight

U. S. Agricultural Research Station, Salinas, CA 93915

Muskmelon male sterile-1 reported by Bohn and Whitaker (1) has not been utilized in F1 hybrid melon production. Plant breeders report ms-1/ms-1 plants difficult to identify. Some breeders have stated that the male sterile phenotype is not stable and have concluded that ms-1 is, therefore, of no value for melon hybrid production. I report evidence indicating that expression of ms-1/ms-1 is stable, but that expression of male fertile siblings is unstable.

Progeny 21322, and F1 from a cross of two plants heterozygous for ms-1, was planted in the greenhouse in a 1:1 soil: sand mixture in a greenhouse flat; 48 seeds per flat. Staminate flowers were scored at anthesis for male sterility. Two to four flowers were scored per plant by two methods. First, presence of pollen was determined by rubbing the anther across the tip of a finger. Second, a crude squash mount of an anther was stained with acetocarmine or methyl blue and observed under low power magnification (100 X) for presence of pollen. A flower was scored as fertile if any pollen-like material was rubbed from the anthers. A flower with even the slightest amount of pollen-like material was scored as male fertile. All flowers from which none or only a slight amount of pollen-like material was rubbed from the anthers were examined microscopically for presence of pollen. A plant was score as male sterile only if all flowers were scored as male sterile by both methods.

Progeny 21322 segregated 74 Ms-1/_:27 ms-1/ms-1; a close fit to the expected 3 fertile: 1 sterile ratio, x2 = 0.1616. A few male sterile plants produced at least one flower with distorted pollen grains similar to those reported by Bohn and Whitaker (1) in ms-1/ms-1 plants. Male fertile segregates produced three types of flowers with respect to amount of pollen that was rubbed from the anthers: abundant; sparse; and none. Three fertile plants produced flowers that were observed to have no pollen when microscopically examined. Thirteen percent of the flowers on male fertile plants were scored as male sterile; 34% of the male fertile plants had at least one sterile flower.

These results indicate that phenotypic expression of ms-1/ms-1 is stable. The source of confusion in selecting ms-1/ms-1 plants in a segregating population is variation in expression of male fertile plants. Once a male fertile flower is found on a plant, that plant should be scored male fertile and rouged from the seed field. Before leaving a plant identified as male sterile in the seed field, several (3 to 4) flowers should be scored male sterile. It is essential to confirm identification of male sterile plants by observing stained anther smears under low power magnification. I have observed as many as ten flowers on a plant to be male sterile when check by rubbing the anthers. When examined under the microscope, they were, however, fertile.

Literature Cited

  1. Bohn, G. W. and T. W. Whitaker. 1949. A gene for male sterility in muskmelon (Cucumis melo L.). Proc. Amer. Soc. Hort. Sci. 53:309-314.
Home About Membership Reports Gene Lists Conferences Links Search NCSU
Department of Horticultural Science Box 7609North Carolina State UniversityRaleigh, NC 27695-7609919-515-5363
Page citation: Wehner, T.C., Cucurbit Genetics Cooperative;
Created by T.C. Wehner and T. Ng, 1 June 2005; design by C.T. Glenn;
send questions to T.C. Wehner; last revised on 1 August, 2007