Oxygen deficiency is a widespread stress factor. Its consequences studied with the seedlings of Triticum aesíivum, under a special consideration of their root growth and morphology, the gas exchange and pyridine nucleotide systém, and the chlorophyll biosynthesis in shoots, are reviewed here on the basis of the general stress concept.
Etiolated oat mesophyll protoplasts and etioplasts released from etiolated protoplasts were able to perform protochlorophyliide (PChlide) reduction but showed a high amount of inactive P633/628» compared with intact leaves. In špite of this, the anabolic reduction charge (ARC, NAPDH+H+/NADP+ + NADPF1+H+) was maintained at 0.66 - 0.77 up to 30 min of irradiation with weak "white light" (10 W m‘2). This indicated a high buffering capacity of the isolated systém to provide NADPF1+H+, only at the expense of intemal reserves. A change in the redox statě of the NADP+/NADPH+H^ couple during protochlorophyliide reduction was not observed in etioplasts. The resulting redox potential was in the range of -330 mV optimal for protochlorophyliide reduction.