The role of phytochelatins in Sinapis alba L. response to stress caused by two toxic elements As and Tl

Abstract

Phytochelatins (PCs) play an important role in the detoxification and homeostasis processes in plants, since xenobiotics complexed by sulfhydryl groups are less toxic than the free ions. This paper describes studies related to PCs synthesis in Sinapis alba L. exposed to As and Tl salts, and in particular to the identification of the PC complexes that are formed in white mustard tissues. To reach the goal, two analytical methods were applied – high-performance liquid chromatography with fluorescent detection analysis after derivatisation of thiol compounds and high-performance liquid chromatography with electrospray ionization mass spectrometry (HPLC ESI MS). The study confirmed the synthesis of PCs in all plant organs under the influence of As salt. Moreover two As-PC complexes were identified: As-PC₃ and As-PC₄. While in the case of Tl – although that element strongly influenced the growth of Sinapis alba L. and to a great extent was transported to above-ground organs – no PC complexes or free PCs were found in plants exposed to Tl salt. Although both elements exist in mustard plant tissues at their trivalent oxidation state, showing high affinity to thiol groups, a defence mechanism associated with the synthesis of PC occurred only in case of arsenic.

Keywords:

• arsenic
• thallium
• phytochelatins
• Sinapis alba L.
• detoxification mechanism

Acknowledgement

The authors wish to thank Agnieszka Lisowska, M.Sc., for the participation in experiments.

Additional information

Funding

The study related to thallium was supported by National Science Centre (NCN), Poland, under Grant number DEC-2011/01/B/NZ8/00052 and the study related to arsenic by Polish Ministry of Science and Higher Education under Grant number NN204 009935.