A new simple recessive gene mutant of the common tomato named "cabbage" with the symbol cb occurred spontaneously in our cultures. The number one variety of differences from normal sibs is exceptionally great. Cabbage has larger, darker green leaves, inconspicuous inflorescences, and fewer and smaller fruits. It has fewer flowers per inflorescence and fewer loculi per ovary. Unilocular ovaries are more frequent in cabbage. Fertility is greatly reduced. Cabbage has typically the diploid number of chromosomes. Its unfruitfulness appears to be due to general physiological causes rather than than to chromosome abnormality. The cells of the sporogenous tissue of the small and often shrunken anthers vary greatly in size. This size difference is continued throughout meiosis. In the large diploid pollen mother cells of cabbage, the nuclei and nucleoli are larger than in the smaller diploid cells. Apparently the primary cause of increased nucleus and nucleolus size is cell size rather than increase in chrormosome nurber or in satellite size. During the last somatic division preceding meiosis there is a strong tendency toward total or partial failure of cytokinesis in the mutant. This may give rise to large pollen mother cells with two diploid prophase nuclei. In such cells reduction proceeds simultaneously in the two nuclei so that eight haploid microspores are usually formed. But three diploid and two haploid nuclei were found in one cell, indicating that restitution nuclei are sometimes formed at A\II\ or thereafter. Tetraploid pollen mother cells occur in the matant from the fusion of the two prophase nuclei of binucleate cells. In a cell with two diploid nuclei non-reduction may occur in both. In one case non-reduction appears to have occurred in a tetraploid pollen mother cell. Occasional tetraploid or binucleate pollen mother cells have been found in normally fruitful sibs of cabbage. These are believed to be due to incomplete dominance of the normal allele.
With some single gene mutants of the tomato have only one known effect, others are pleiotropic, using the term in the etymological sense of "in many ways or modes". The d\1\ or dwarf mutation affects numerous organs of the plant and, was formerly known as a subspecies. The mutant cabbage is even more remarkable for the number and variety of differences from the normal. This diversity of effects suggests that the pleiotropy of cabbage may be "genuine" or "gene-ative", using the terms proposed by Grunsberg (Syposium on growth and differentiation, Soc. Exp. Biol. Oxford, England. 1948) and, by Adorn (Soc. Exp. Biol. No. 2, 177-195, 1948).
The occurrence of a single gene - single effect relation in Neurospora is evidence against the existence of gene-active pleiotropy but perhaps there has been a tendency to select mutants with single effects or to overlook secondary effects in this organism. In the case of cabbage and of dwarf no evidence suggesting that the pleiotropy is due to several closely linked genes has been found. Cabbage appears to be a single gene mutant of somewhat reduced viability. The locus is in chromosome III, about 28 crossover units from y, the mutant gene for non-yellow skin color of the fruit.