POLYSPORY IN AN AMPHIPLOID OF TRITICUM-AGROPYRON HYBRIDS

Abstract

An amphiploid line in the F9 generation tracing to the cross, Triticum turgidum × Agropyron intermedium, was found to contain plants which at meiosis showed a spindle abnormality. In plants showing this abnormality, over 50 per cent of the microsporocytes contained 5 to 8 microspores instead of the normal 4. The occurrence of microspores with two nuclei was also common and was more prevalent in tetrads than in hexads to octads. Meiosis was found to be regular up to metaphase II. At this time a secondary spindle was formed and the chromosomes divided and moved to the poles of primary or secondary spindles. The number of chromosomes on secondary spindles ranged from 3 to one-half the complement of 32–35. After telophase II wall formation was usually initiated enclosing the resulting nuclei; where walls failed to form microspores were two-nucleate. The result of this abnormality was to bring about almost complete sterility in the affected plants.