Tonoplast of Saintpaulia sp. could be Damaged by Decreasing Temperature

Abstract

Leaves of African violet (Saintpaulia sp.) are sensitive to decreasing temperature and were damaged when temperature decreased not only from 25 to 10^oC but also from 35 to 20^oC. After temperature decrease, a layer of palisade cells were strongly damaged and died at last, although epidermal cells and spongy cells were not. Decrease of pH in the cytoplasm of palisade cells was determined by fluorescent dye (BCECF-AM) during decreasing temperature, but the fluorescence of chloroplasts was successively decreased after finishing the treatments. These results could suggest the first damage of tonoplast caused by decreasing temperature.