The recent renewal of interest in tomato male sterility prompted us to look over our stocks of sterilities discovered as spontaneous mutants in fields at harvest time. Believe it or not, the following three mutants were encountered in 1965 and 1967 and remained "dormant" in our seed collection until recently. Fortunately the stored seeds still germinated.
ms-10^36 (2-635) A single plant with the earmarks of bona fide male sterility was found in a field of VF36 by Boynton, Khush, Monaco, and Rick in a harvest field near the Sunset Theater (!) between Davis and Woodland, September 25, 1965. At that time, stamens were twisted and so greatly reduced in size that stigmas were exposed consistently, despite the low stigma position characteristic of VF36. The same subnormality has been observed consistently throughout our experience over several seasons except that in the very late season stamens may develop sufficiently to hide the stigma to a minor extent. No sporogenous material is present in mature anthers, and only premeiotic PMC are found in immature anthers; degeneration must therefore take place before meiosis, and selfing from exceptional pollen formation seems highly unlikely. Only parthenocarpic fruits were found on any of the untreated (some 60) plants under field and greenhouse conditions.
F2 segregation in three families totalled 105 fertile: 37 male-sterile; three BC families segregated 28 fertile: 23 male-sterile. A cross between this mutant and L. pennellii yielded Ells, which were backcrossed to the sterile parent and the small progenies therefrom were analyzed electrophoretically. Strong linkages were detected between ms and both Est-7 and Prx-2. Dave Pratt independently detected a tight linkage with aw, leaving no doubt that this gene has its locus on 2L. This location plus the remarkable similarity with the ms-10 phenotype stirred us into making an allele test, and, sure enough, all three crosses yielded sterile segregants, the totals being 14 fertile and 17 sterile. The allele superscript 36 was chosen because the variant was found in VF36.
The following two mutants were found in the same field of VFN8 in Solano County between Davis and Dixon on October 6, 1967 by Andrgsfalvy and Rick. They are reported here because some interest might exist in male sterilities in this outstanding triple-resistant cultivar.
ms-45 (2-659) Anthers were long, slender, and uniformly pale (same color as corolla) in the original plant and all segregants from the same stock. Depending upon ambient conditions, stigmas may be exposed or covered, but generally covered. Breakdown occurs in late meiosis or early microsporogenesis, and vestigia tend to be resorbed in later anther development. No seedy fruits have been observed on any plants in field or greenhouse save those resulting from artificial pollination. The overall F2 segregation observed in eight families was 81 fertile: 25 sterile. In six BC families the total segregation was 50 fertile: 53 male-sterile. No linkage information was obtained.
ms-46 (2-681) Morphological and cytological features were identical with those of ms-45 in all material examined, including the original plant. The remarkable resemblance between two sterile plants in the same field of such a recently bred line led us to suspect that both were the same male sterility tracing to a single original mutation. But such are the vagaries of Mother Nature, that reciprocal allele tests between the two showed complementation, eleven plants in one and ten in the other, all fertile; hence they must be independent mutations! On the basis of our false assumption, we grew only preliminary segregating populations which gave nine fertile: six ms in F2 and six fertile: six ms in BC.