Expression of a mutated melon ethylene receptor gene Cm-ETR1/H69A affects stamen development in Nicotiana tabacum

To investigate the role of an ethylene receptor gene in plant reproduction, we introduced a mutated melon ethylene receptor gene, Cm-ETR1/H69A, into tobacco plants and generated 11 independent transformants. In 5 of the 11 transformants, the flower longevities were longer than that of the wild type, indicating that the transformants had a reduced sensitivity to ethylene than the wild type. The seed yields of these transformants were lower than those of the wild-type plants. The reduced seed yields were mainly caused by abnormal stamen development, modification of floral architecture, and reduced pollen production. Filament elongation was reduced in the transformants, resulting in the heterostyly type of floral architecture. Histological observation of anthers at several developmental stages showed that in transgenic plants, tapetum degeneration occurred later than in the wild type. These results suggest that stamen development is related to ethylene sensitivity.