Zinc accumulation patterns in four Anthyllis vulneraria subspecies supplemented with mineral nitrogen or grown in the presence of their symbiotic bacteria
Résumé
This work examines Zn accumulation in four Anthyllis vulneraria subspecies supplemented with mineral nitrogen or grown in the presence of their symbiotic bacteria. Anthyllis vulneraria subspecies were grown hydroponically in the presence of high levels of ZnSO4. The plants were either grown in symbiosis with one of two non-metallicolous or metallicolous Mesorhizobium inoculants or in the presence of KNO3. When exposed to 1,000 mu M Zn, shoot and root biomass of three out of our four Anthyllis subspecies cultivated with NO3 dropped significantly by about 24-28 %; carpatica, the fourth subspecies, was not affected. Subspecies carpatica Zn tolerance was confirmed when in symbiosis with the metallicolous strain. In the presence of 1,000 mu M Zn, the different Anthyllis subspecies concentrated more Zn in their roots than in their shoots and only subsp. carpatica accumulated a significant amount of Zn in its shoots. The most remarkable feature was the drastic decrease in Zn concentration in both roots (up to 2.5-3 fold) and shoots (2.6-fold) of subsp. carpatica exposed to 1,000 mu M Zn and nodulated whatever the Mesorhizobium strain used, compared to the N-grown plants. Our results bring new perspectives as regards phytostabilization, with the potential use of a rhizobium-inoculated leguminous subspecies displaying unusual Zn tolerance.