Study of Zn accumulation and tolerance of HMA4 TILLING mutants of Brassica rapa grown under Zn deficiency and Zn toxicity

Abstract

Nowadays, Zinc (Zn) deficiency is the most widespread micronutrient deficiency but simultaneously Zn toxicity is produced due to environmental pollution. A potential method to alleviate Zn deficiency and to reduce Zn concentration in soils is through the generation of plants with enhanced capacity for Zn accumulation and higher tolerance. This could be achieved through the modification of HMA4 transporter. BraA.hma4a-3 is a TILLING mutant plant that presents one modification in HMA4 transporter. Thus, in this study we analyzed the potential of BraA.hma4a-3 for Zn accumulation and Zn deficiency and toxicity tolerance. BraA.hma4a-3 and parental R-o-18 plants were grown with different Zn doses: 1 µM ZnSO4 (Control), 0.01 µM ZnSO4 (Zn deficiency) and 100 µM ZnSO4 (Zn toxicity). Parameters of biomass, Zn concentration, photosynthesis, oxidative stress, N metabolism and amino acids (AAs) were measured. BraA.hma4a-3 did not affect plant biomass but did increase Zn accumulation in leaves under an adequate Zn supply and Fe under control and Zn deficiency doses. Regarding stress tolerance parameters and N metabolism, BraA.hma4a did not produce alterations under control conditions. In addition, under Zn toxicity, parameters suggest a greater tolerance. Briefly, the obtained results point to BraA.hma4a-3 as a useful mutant to increase Zn accumulation