Effect of Fe deficiency on mitochondrial alternative NAD(P)H dehydrogenases in cucumber roots

Iron deficiency affects the function of respiratory chain, mainly at the complex I and complex II levels. Since plant mitochondria posses alternative NAD(P)H dehydrogenases located in the inner-membrane, oxidising NAD(P)H from both cytosol and matrix, we investigated these activities in mitochondria of Fe-deficient roots. External and internal NAD(P)H dehydrogenase activities increased in Fe-deficient mitochondria. Accordingly, NDB1 protein strongly accumulates while NDA1 does not show relevant differences in Fe-deficient roots. The data presented support, for the first time, the hypothesis that Fe deficiency induces the alternative NAD(P)H dehydrogenases bypassing the impaired complex I.