Hydrogen peroxide functions as a cell death signal for hybrid lethality in the F1 of Nicotiana gossei $times; N. tabacum

Abstract

F1 seedlings of Nicotiana gossei Domin × N. tabacum L. show hybrid lethality caused by an expansion of programmed cell death from the base of the hypocotyl. The cell death proceeded at 26 °C but not at 37 °C. The levels of O2− and H2O2, reactive oxygen intermediates, were higher in the plants grown at 26 °C than 37 °C. The cell death was suppressed by the application of catalase or inhibitors of NADPH oxidase, but not by superoxide dismutase (SOD) or mangan-desferrioxamine. This suggests that H2O2 is involved in the cell death process rather than O2−. The cell death was promoted in the F1 hybrid of N. gossei × transgenic N. tabacum overexpressing the rice CuZn-SOD, whereas it was suppressed in the F1 hybrid of N. gossei × transgenic N. tabacum overexpressing the rice cytosolic ascorbate peroxidase. Thus H2O2 causatively links to cell death in the hybrid.