Plant Anaerobic Stress I . Metabolic Adaptation to Oxygen Deficiency

The establishment and further development of a novel branch of science in the field of ecological physiology, biochemistry and molecular biology, dedicated to plant life under hypoxic and anoxic stresses, is considered in the present review focusing upon strategies of adaptation and injury exhibited by plants under hypoxia and anoxia. Taking into account that the results of investigations over the last few decades confirmed the conclusions about the existence of two general strategies for plant adaptation to hypoxic and anoxic stresses: (a) true tolerance realized at the molecular level due to cardinal rearrangement of cellular metabolism under conditions of oxygen deficiency or complete absence of oxygen, and (b) apparent tolerance that is brought about by avoidance of anaerobiosis thanks to long-distance oxygen translocation, the accumulated experimental information is considered and discussed mainly with respect to basic strategies. The physiological role of anaerobic proteins synthesized under conditions of hypoxia and anoxia as well as advances in molecular biology and molecular genetics in the study of regulation of synthesis of these proteins at the level of transcription, translation and post-translation are discussed. The key significance of energy (glycolysis and fermentation) and related processes of carbohydrate (mobilization and utilization of reserved carbohydrate) metabolism in plant metabolic adaptation to oxygen deficiency is stressed. Special attention is given to an earlier period of active investigations in this field that played a substantial role in the establishment and international recognition of this new biological discipline. The strategy of avoidance of anaerobiosis by long-distance oxygen translocation and some other aspects of plant life under hypoxia and anoxia will be considered in the following publication (Vartapetian, Sachs, Fagerstedt 2008). _____________________________________________________________________________________________________________