Facile induction of apoptosis into plant cells associated with temperature-sensitive lethality shown on interspecific hybrid from the cross Nicotianasuaveolens x N-tabacum

Two lines of suspension culture cells were obtained from a hybrid seedling of Nicotiana suaveolens Lehm, x N. tabacum L. cv. Hicks-2 expressing temper ature-sensitive lethality, One of them (LH line) was inducible cell death i n accordance with the lethality at 28 degreesC but not under high-temperatu re conditions (36 degreesC). Another one (SH line) lost the lethality and s urvived at 28 degreesC. The cells of LH line showed apoptotic changes when they were cultured at 28 degreesC. Fragmentation of nuclei was correlated w ith the lethality in the cells, as confirmed by fluorimetry of the nuclear DNA using laser scanning cytometry, Agarose gel analysis of DNA extracted f rom the cells expressing the lethality revealed a specific ladder pattern s uggesting nucleosomal fragmentation that is one of the biochemical characte ristics of apoptosis, From these facts, we confirmed that the process of ce ll death leading to hybrid Lethality in the cells is certainly apoptosis, H ybrid cells were used in the experiments to estimate the point of no return in temperature-sensitive lethality and to examine the influence of cation in DNA fragmentation during apoptosis, The utility of hybrid cells as an ex perimental system for studies of hybrid lethality and apoptosis in plants w as confirmed.