摘要 : Hybrid seedlings from the cross Nicotiana tabacum * N. debneyi, obtained by test-tube pollination and ovule culture, expressed lethality at 28deg C. Characteristic lethal symptoms in these hybrid seedlings were browning of hypocot... 展开 Hybrid seedlings from the cross Nicotiana tabacum * N. debneyi, obtained by test-tube pollination and ovule culture, expressed lethality at 28deg C. Characteristic lethal symptoms in these hybrid seedlings were browning of hypocotyls and roots. Hybrid seedlings did not express any lethal symptoms at 32-36deg Cand their growth was most vigorous at 34deg C. When hybrid seedlings cultured at 34deg Cwere transferred to 28deg C, their growth stopped and lethal symptoms were expressed. During the progressive expression of lethality, apoptotic features such as chromatin condensation, nuclear fragmentation, and internucleosomal fragmentation of DNA were detected. These observations indicate that hybrid lethality in the cross N. tabacum x N. debneyi is accompanied by programmed cell death (PCD). On the other hand, there was no sign of PCD in hybrid seedlings cultured at 34deg C. Since similar expression of lethality accompanied by apoptotic features was previously reported in the reciprocal cross, W. debneyi x N. tabacum, it was concluded that PCD and hybrid lethality are due to the interaction of coexisting heterologous genomes and not to a cytoplasmic effect. Additionally, this demonstrates that PCD related to hybrid lethality did not occur in hybrids that did not express lethality. 收起