The Meiotic Divisions of Haploid, Diploid and Tetraploid Tomatoes with Special Reference to the Prophase

Abstract

1. The tomato polyploid series, haploid, diploid, and tetraploid has been described with special reference to the prophase of microsporogenesis.
2. The resting nucleus of the haploid contains prochromosomes. There is no pairing of threads and the spireme in prophase is not continuous. Metaphase-anaphase distribution is random. Second metaphase is regular except that three spindles are sometimes present. Normal spores occasionally result from non-reduction at first division. Hexads are occasionally found.
3. The diploid produced by the decapitation method, is completely homozygous, and the meiotic behavior is entirely regular.
4. The tetraploid, also produced by the decapitation method, is likewise homozygous. Four strand pairing occurs at synapsis. At diplotene the chromosomes usually appear as tetrasomes, but become separated into disomes at diakinesis and metaphase. Disjunction is regular and subsequent behavior is normal and similar to that of the diploid. Tetrads always appear normal.
5. Measurements were made an the diameters of pollen, pollen mother cell, nucleus and nucleolus as well as tetrad, microspore and microspore nucleus, and these were compared in the, different individuals. A definite increase in size was noted in each Gase when the chromossme number was doubled.