Possible role of HMA4a TILLING mutants of Brassica rapa in cadmium phytoremediation programs

Abstract

Cadmium (Cd) is a dangerous transition element that causes environmental and health problems due to its high mobility in the soil-plant system. In plants, Cd causes serious alterations in physiological processes, affecting different vital functions such as photosynthesis. Species such as Brassica juncea and Brassica rapa have been selected as suitable plants for phytoremediation purposes due to their ability to tolerate the toxic effect of heavy metals. In order to improve this strategy, techniques of plant mutagenesis such as TILLING (Targeting Induced Local Lessions in Genomes) have been employed. In the present work we studied the role of the HMA4 gene in the tolerance to Cd toxicity (100 μM CdCl2) using a TILLING mutant of B. rapa (BraA.hma4a-3). These mutant plants presented a lower biomass reduction and a higher Cd concentration in leaves. An increase in the GSH/GSSG ratio, in the content of photosynthetic pigments and a reduction of oxidative stress was observed, as well as a better photosynthetic index, confirming that BraA.hma4a-3 plants showed a higher tolerance to Cd. In conclusion, according to the results obtained in this work, BraA.hma4a-3 plants could be used for phytoremediation purposes of Cd contaminated soils.