[Wheat root cells functioning under inhibition of I and II complexes of mitochondrial respiratory chain]

A joint effect of rotenone and malonate on the intensity of respiration, output of K+ and ultrastructure of wheat root cells treated for 6 h was studied. The addition of malonate to rotenone containing solution, in which wheat roots had been incubated for an hour, caused further decrease in respiration intensity and K+ output into external medium. Many mitochondria acquired torus shape in 2h after malonate addition. The increase in respiratory intensity and re-entry of K+ from the incubation medium into the cells were observed during following hours of incubation. We assume that reparation and adaptation processes took place in this case. The observed contacts of endoplasmic reticulum lumens with mitochondria are indicative of possible synthesis of an enzyme able to metabolize malonate to acetyl-CoA and CO2. We propose that torus shape of mitochondria is due to the increase in their outer surfaces, that, in turn, is a result of activation of external NAD(P)H-dehydrogenase. These findings may be evidence of possible adaptation of the root cells to the joint effect of the inhibitors.