STABILITY OF ENHANCED YIELD AND METAL UPTAKE BY SUNFLOWER MUTANTS FOR IMPROVED PHYTOREMEDIATION

Abstract

Plant biomass and metal shoot accumulation are key factors for efficient phytoextraction. In a previous study, chemical mutagenesis has been used to improve the phytoextraction potential of sunflowers. The main goal of the present study was to assess the stability of sunflower mutants with improved biomass and metal accumulation properties in the 3^rd and 4th generations. As compared to control plants, the best M₃ mutants showed the following improvement of metal extraction: Cd 3–5-fold, Zn 4–5-fold, and Pb 3–5-fold. The best M₄ sunflowers also showed enhanced metal extraction: Cd 3–4- fold, Zn 5–7-fold, Pb 6–8-fold and Cr 5–7-fold. The control sunflower inbred line IBL 04, grown directly on the field, accumulated metals in individual organs in the following decreasing order: Cd and Zn: leaves > stem > roots > flower > seeds; Cr: roots > flower > seeds > leaves > stem. The best sunflower mutants showed either higher metal accumulation in shoots or enhanced metal accumulation in roots, suggesting to improved phytoextraction or rhizofiltration efficiency, respectively.

KEY WORDS:

• Helianthus annuus L.
• genetic stability
• metal accumulation
• metal extraction
• mutagenesis
• non-GM approach
• phytoremediation
• sunflower

ACKNOWLEDGMENTS

This work was part of COST Action 859 “Phytotechnologies to promote sustainable land use and improve food safety” (Swiss Project SER C04.0207). Seeds of M₃ sunflower mutants were obtained within the EU-Framework programme “Quality of life and managing of living organisms (QLRT-2001-00429): PHYTAC-Development of systems to improve phytoremediation of metal contaminated soils through improved phytoaccumulation”. Both projects were financed by the Swiss Secretariat for Education and Research.

Notes

*Results of M₂ sunflower mutants (Nehnevajova et al., 2007b). Plant density 60 000 sunflowers per ha.