Spontaneous Chromosome Fragmentation in Trillium erectum L.

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Abstract
The frequency of spontaneous chromosome fragmentation was studied in T. erectum. Fragments (at 1st anaphase and microspore metaphase) and micronuclei (at quartet and micros-pore interphase) were counted and treated statistically. Analysis of micronuclei at microspore interphase in 15 plants showed no significant difference between buds within a plant or anthers within a bud. However, the 15 plants fell into 2 groups with mean frequencies of 0.666 and 2.908 micronuclei per 100 microspores. There was no overlapping and the difference was statistically significant. It is concluded that "background" counts of spontaneous aberration should be made whenever accurate control values are needed in radiation expts. No significant difference was found between aberration frequency at 1st anaphase (1.97% fragments), quartet (2.00% micronuclei) and microspore metaphase (2.04 fragments per 100 PMC) when material was all collected from the same plants. However, microspore interphase had an aberration frequency of 6.00 per 100 PMC or about 3 times that of the other 3 stages. The reason for the significantly higher frequency at interphase is not understood. The results suggest that the values obtained at any one of 3 stages (1st anaphase, quartet, or microspore metaphase) can be used interchangeably as a control count of spontaneous fragmentation.