Effect of dithiothreitol (DTT) and diethylditiocarbamate (DDC) on watered and water stressed bean leaves

Abstract

The effect of infiltration of 3 and 5 mM DTT and 10 mM DDC in watered and water stressed bean leaves, upon low or high intensity light has been assessed, in order to compare the relative importance of non-photochemical energy dissipation and active oxygen scavenging on photosynthesis. qN, in high light, was reduced by 3 and 5 mM DTT in stressed plants, and only by 5 mM in watered. The low qP value in stressed leaves was not further reduced by DTT, instead, Fs increased. Restrictions on the capacity for qN formation, induced by DTT, however, did not result in a lower capacity to recover Fm' after 20 min darkness in neither watered or stressed leaves upon high light, or watered plants at low light. On the contrary, stressed plants under low light, recovered Fm' up to a slightly higher value compared to the other treatments and control. DDC, only affected qN in low light stressed plants, slightly increasing it, as well as Fs, also decreasing qP. In Watered plants, DDC negatively affected the Fm' recovery, in high and low light. Despite the big differences in qN and qP, among water regimes, both reached similar photosynthetic rates in low light. The increased qP after DTT infiltration, as well as the higher Fm' recovery in stressed plants under low light, suggest that qN might reduce, under such conditions, activation of assimilatory enzymes. Stressed leaves were more resistant to qN and SOD inhibitors compared to watered. Supported by FONDECYT 1990077