Structural organization of chloroplast of tomato plants Solanum lycopersicum transformed by Fe-containing superoxide dismutase

Abstract

In this work we analyzed the results of the transformation of tomato plants Solanum lycopersicum by gene FeSOD1 from Arabidopsis thaliana, equipped with the signal sequence for targeting into chloroplasts. PCR analysis showed that the gene was integrated into the genome of several tomato plants that underwent transformation followed by selection in the kanamycin-containing medium. Two lines, provisionally denoted as nos. 6 and 8, were selected from the independent transformants. Line 6 was characterized by a reduced growth rate and altered leaves and line 8, by normal growth and leaves typical for control plants. Both lines showed a significant increase in SOD activity. In line 8 the increase in SOD activity was accompanied by an increase of ascorbate peroxidase activity, and in line 6 this effect was not present. Electron microscopic analysis of parenchymal and guard cells of both lines was performed, with an emphasis on the ultrastructural organization of chloroplasts. It is shown that the chloroplasts of the two transgenic lines differ in the number and size of starch grains and deposited plastoglobules as well as in the organization of lamellae and grana. Taken together, the results indicate that the expression of the introduced gene FeSOD1 has a significant effect on metabolic processes in the plastids. The findings are discussed in relation to the hypothesis about the importance of low concentrations of ROS for the integration of structure and function of chloroplasts.