Large scale screening of heavy metal tolerance in flax/linseed (Linum usitatissimum L.) tested in vitro

The in vitro shoot-tip culture obtained from hypocotyl segments was established for screening of genetically based ability to accumulate and/or tolerate metals, Cd and Zn, in a set of commercial flax/linseed (Linum usitatissimum L.) varieties grown in the Czech Republic. Callus-induction and organogenesis in explants (bud and root regeneration, shoot development) at increasing concentrations of Cd and Zn in the cultivation medium were evaluated. Sub-lethal Cd and Zn levels (19 mg/l Cd2+ and 33 mg/l Zn2+) were established for in vitro selection system to find out flax/linseed lines with improved Cd/Zn accumulation and/or Cd/Zn tolerance. Metal accumulation in regenerated shoots, the most important parameter for the assessment of variety accumulation capacity, was influenced by regeneration ability of explants in individual varieties. Group of tolerant varieties was selected using established in vitro method. Two different mechanisms of Cd or Zn tolerance were found out. The selected flax/linseed varieties with the highest metal accumulation capacity can be used for phytoremediation purposes immediately. They also can be employed in the agrobacterial transformation experiments for additional metal accumulation increasing. Varieties with the highest Zn accumulation can be used in next studies with the aim to select variety with the high Zn accumulation in seeds which can be utilized in the case of the Zn deficiency in human diet.