Abnormal Mitosis in Tobacco Plants Forming Hereditary Tumours

Abstract

TOBACCO species hybrids Nicotiana glauca (n=12) × N. Langsdorffii (n=9), N. paniculata (n=12) × N. Langsdorffii, N. suaveolens (n=16) × N. Langsdorffii, etc., formed hereditary tumours1–3 all over the plants when they were as old as 4–7 months. Each plant of the amphidiploid N. glauca × N. Langsdorffii (=N. Vavilovii; n= 21) also formed hereditary tumours at about the same age. In searching for the cause or causes of tumour formation1–5 I also examined the frequency of the abnormal mitosis in longitudinal sections of root tips of old N. Vavilovii plants. I counted normal late anaphases and late anaphases with chromatin bridges and obtained the following figures in studying 752 cells of five different plants which formed hereditary tumours: 21·4, 12·2, 10·7, 8 and 4·2 per cent anaphases with at least one chromatin bridge. 264 anaphases of the maternal plant N. glauca and 232 anaphases of the paternal plant N. Langsdorffii were also studied. No chromatin bridge was found in these anaphases.