Cytological and Other Features of Variant Plants Produced from X-Rayed Sex Cells of Nicotiana tabacum

Abstract

Appropriate x-ray dosage applied to flower buds of N. tabacum may be followed by the appearance of large numbers of variant individuals in the selfed progeny. There was evidence that variation can be induced by x-raying the mature pollen. Apart from the abscission of all smaller flower buds, no visible somatic effect followed the x-ray dosage employed. The x-ray variants exhibited numerous types of modification of all vegetative and floral organs and reduction in fertility to various degrees. Cytologically the variants examined proved (1) to be normal in chromosome number and behavior, (2) to show non-conjunction of one or more pairs of chromosomes, (3) to be the products of non-disjunctional phenomena, and (4) to possess fragmented chromosomes.