Abstract: Measuremem of cytoplasmic [ Ca2 + ]i in Daucus carota var. sativa DC. was improved first modifying the preparative medium of, protoplast, then, under norm. al physiological condition, introducing fluorescent Ca2 + indicators indo-1 K + and fura-2 K + into the protoplasts with gentle and non-invasiva loading procedure. The cytoplasmic free Ca2 + could be well labeled. Cytoplasmic calcium levels of individual cells were measured via single-wave microfluorometry. That [ Ca2 + ]i of protoplasts of carrot and its callus labeled with indo-1 K+ and with fura-2 K+ were 88.3 nmol/L, 263.0 nmol/L and 99.9 nmol/L, 255.5 nmoL/L, respectively. It was shown that cytoplasmic [ Ca2 + ]i of carrot callus in the state of dedifferentiation in cell cycle was much higher than carrot root cells in the differentiated resting cells. In addition, the authors performed the in vitro calibration of the two fluorescent Ca2 + indicators respectively to determine their linear relationship between calcium ion concentration and the two indicators in order to ensure the reliability of measurements.

Key words: aucus carota, Protoplasma., Cytoplasmic calcium, indo-1 K+ , fura-2 K+