Stable Artificial Autopolyploids of the Zn/Cd Accumulator Arabidopsis arenosa-A Promising Genetic Resource for Phytoremediation

Arabidopsis arenosa is a good candidate for phytoremediation due to its high tolerance to Zn and Cd as well as its accumulation ability. However, its small size and low biomass are the largest obstacles to applying it on a broad scale. The aim was to obtain polyploid specimens, which tend to have higher biomass to increase the accumulation and translocation capacity of heavy metals in this metal-tolerant plant. Doubled polyploids (octaploids) were obtained via indirect organogenesis on a 1/2 MS medium supplemented with 1 mg L-1 TDZ, followed by rooting on the same medium without growth regulators. Callus tissue of a high endopolyploidy level (the (Sigma >2C)/2C ratio over 2.5) obtained on seedling fragments on 1/2 MS supplemented with 2 mg L-1 2,4-D + 2 mg L-1 BAP served as a source material. Among the regenerants successfully obtained (without using antimitotic agents), over half, regardless of the stage of regenerant development, were octaploid (54-78%; 2C DNA = 1.642 pg). Octaploids were not affected by ploidy or in vitro culture conditions; they were fully fertile, produced normal pollen (similar to 97% of viability), and set seeds capable of germinating (78%). Their cell and organ size was affected by genome doubling resulting in longer stomata, bigger pollen grains, and flowers with a larger area and width in comparison with tetraploid regenerants and initial plants. The promising results of measurements of morpho-anatomical, physiological, and reproductive parameters indicate that, in the future, after passing tolerance tests, the obtained polyploids could be used in phytoremediation of metal-contaminated areas.

Automated summary

Arabidopsis arenosa is a promising candidate for phytoremediation due to its high tolerance and accumulation ability. In this study, octaploid specimens were obtained through indirect organogenesis, resulting in higher biomass and improved capacity for heavy metal accumulation and translocation. The fully fertile octaploids exhibited larger cell and organ size compared to tetraploid regenerants and initial plants. These promising results indicate that the obtained polyploids could be used in the future for phytoremediation of metal-contaminated areas.