[Activation of the chloroplast respiration increases chlorophyll fluorescence yield in Chlorella adapted to darkness...

A tenfold increase in chlororespiration during dark incubation of Chlorella perynoidosa Chick at high temperature doubled the initial chlorophyll fluorescence yield (F0). The presence of iodacetamide or unmetabolizable glucose analog 2-deoxy-D-glucose prevented increase in both chlororespiration and F0 yield. The rates of chlororespiration and F0 yield growth demonstrated a similar pattern of temperature dependence. Inhibition of electron transport between QA and plastoquinone prevented increase in F0 during dark respiration of the cells at high temperature. Apparently, a pool of plastoquinone was restored in the chlororespiratory chain during the dark incubation at 37.5-41 degrees C and plastoquinone exchanged electrons with QA. This is the cause of QA reduction and subsequent increase in F0 yield.