A novel NADP-isocitrate dehydrogenase contributes to cadmium/lead detoxification and tolerance in plants.

Excessive heavy metal pollutants in soil seriously damage ecological systems and the environment. Dianthus spiculifolius shows strong tolerance to Cd/Pb and readily accumulates both metals. Isocitrate dehydrogenase (IDH) is key enzyme in the tricarboxylic acid cycle, which is involved in the plant response to a variety of abiotic stresses. Previous transcriptomic analyses suggested that DsIDH in D. spiculifolius plays a role in Cd/Pb detoxification. In this study, we found that the transcript level of DsIDH was significantly increased under Cd/Pb stress. Transiently expressed DsIDH localized at the chloroplasts in tobacco leaves. Transgenic yeast lines overexpressing DsIDH showed increased tolerance to Cd and Pb and decreased accumulation of Cd and Pb. Compared with their respective wild types, transgenic Arabidopsis and D. spiculifolius overexpressing DsIDH showed increased IDH activity, increased tolerance to Cd/Pb, and decreased heavy metal contents. The increased activity of IDH significantly accelerated the decomposition of isocitrate and increased the production of α-ketoglutaric acid and NADPH, which reduced damage caused by the reactive oxygen species produced in response to Cd and Pb stresses. The DsIDH might be a novel tolerance-related candidate gene useful for decreasing the storage of toxic heavy metals in crops.