Rick, C. M.
Since the variety Earlypak is being used to a considerable extent as a parent for F\1 tomato hybrids male-serile mutants were sought in that variety to facilitate production of hybrid seed. The first opportunity to search large fields of this variety came in 1953, when Mr. Underhill of the San Joaquin Country Extension Service Office arranged for a visit to some fields planted near Collegeville in that county. Collections were made from several plants that manifested the traits of male-sterility and from these two were selected as the most promising for hybrid seed production. They are described as follows:
2-273 (ms\23) Earlypak. Sterile flowers easily distinguished by their anthers, which are slender and distinctly paler than normal. Stigmas appear at mouth of tube, but mostly sunken slightly. Smears of mature anthers reveal no pollen. Meiosis is normal but is delayed to a remarkable extent, occurring in buds of 4-6 mm. length. It is also evident that meiosis is prolonged for a longer period than normal. Collapse occurs after meiosis is complete but before the cytokinesis separating the tetrads. F2 seg. 51+:7ms; BC seg. 21+:29ms.
2-277 (ms\24) Earlypak. Very likely a different gene from ms\23 since appearancee of flower and natur of development are entirely different. Flowers are more difficult to distinguish from normal than those of ms\23. Stamens somewhat more slender and slightly but perceptibly paler that normal. Stamens considerably shorter than normal, leaving stigmas exposed in the majority of flowers. Mature anthers with 100% aborted pollen, very uniform for medium size. Meiosis normal in all aspects including time of occurrence. Microspores releasel normaly from tetrads, but degenerate shortly thereafter. F2 seg.43+: 13 male-sterile; BC seg. 32+: 17 male-sterile.
In TGC 3:21 I indicated that at that time I had no intention of investigating linkages of ms genes. Recently one of our graduate students, David Pratt, has developed an interest in this ssubjects and is currently testing for linkages of all of our male-sterile mutants in San Marzano (ms\3, 5-13, 15). The start of this project is mentioned here with the hope that there will be no duplication of effort.