Role of Ethylene on Flower Senescence of Torenia.

Flower senescence of Torenia fournieri was investigated in relation to ethylene production and sensitivity. Ethylene production of flowers increased with flower senescence ; pistil contributed to climacteric increase of ethylene production whereas other organs such as the petal, stamen, and calyx did not. Flowers were not sensitive to ethylene on the day of anthesis, but developed sensitivity as the flower senesced. Pollination and wounding of stigma markedly accelerated abscission of flowers, which was accompanied by climacteric ethylene production. Climacteric ethylene, following pollination and stigma wounding, was mainly produced by the pistil, particularly the style with stigma. The abscission of the intact, pollinated and stigma-wounded flowers was significantly inhibited by treatment with silver thiosulfate complex (STS), an ethylene action inhibitor. These results clearly show that the flower senescence of Torenia is mainly regulated by ethylene.