The role of Cd-binding proteins and phytochelatins in the formation of resistance to cadmium in the cell lines of Nicotiana plumbaginifolia

Abstract

The callus lines of Nicotiana plumbaginifolia with equal resistances to cadmium were obtained under different selective conditions, including without the inhibition of phytochelatin synthesis (the Cd-R line) and with the inhibition of a butionine sulfoximine (the Cd-Ri line). The level of phytochelatin synthesis in the Cd-R and Cd-Ri lines exceeded the control value by fivefold and twofold, respectively. Three cadmium-binding proteins with molecular masses of 41, 34, and 19 kDa were observed mainly in the control line. A common feature of both resistant lines was the expression of cadmium-binding proteins with molecular masses of 40, 34, and 19 kDa. The synthesis of relatively low-molecular cadmium-binding proteins was characteristic of the resistant lines as follows: the line Cd-R expressed the proteins with molecular masses of 12.5, 11.5, and 9 kDa, while the Cd-Ri line expressed those with molecular masses of 13 and 10 kDa. We supposed that both phytochelatins and Cd-binding proteins contribute to the resistance to cadmium in N. plumbaginifolia callus lines, and, additionally, that changes in the synthesis of low-molecular Cd-binding proteins can compensate for the lack of phytochelatins.