2002 Volume 19 Issue 4 Pages 267-270
Interspecific hybrids of Nicotiana debneyi × N. tabacum L. show hybrid lethality, which is one of the mechanisms for reproductive isolation. Apoptotic changes were detected in the cells of hybrid seedlings expressing lethality at 28°C, but not at high temperature (34°C) indicating lethality was suppressed. When hybrid seedlings cultured at 34°C were transferred to 28°C, lethal symptoms appeared. Chromatin condensation and nuclear fragmentation were observed in leaf protoplasts isolated from hybrid seedlings expressing lethality. Agarose gel analysis of DNA extracted from leaves of hybrid seedlings revealed a specific ladder pattern, suggesting nucleosomal fragmentation. Nuclear fragmentation was correlated with lethal symptoms in hybrid seedlings, as confirmed by flow cytometry. These results were observed in hybrid seedlings transferred to 28°C from 34°C but not in hybrid seedlings maintained at 34°C. This phenomenon suggests that apoptosis in hybrid seedlings from the cross N. debneyi×N. tabacum is temperature dependent.
