Biotechnological approaches to creation of hypoxia and anoxia tolerant plants.

The present work provides results of a number of biotechnological studies aimed at creating cell lines and entire plants resistant to anaerobic stress. Developed biotechnological approaches were based on earlier fundamental researches into anaerobic stress in plants, so "Introduction" briefly covers the importance of the problem and focuses on works considering two main strategies of plants adaptation to anaerobic stress. Those are adaptation at molecular level where key factor is anaerobic metabolism of energy (true tolerance) and adaptation of the entire plant via formation of aerenchyma and facilitated transportation of oxygen (apparent tolerance). Thus, sugarcane and wheat cells resistant to anaerobic stress were obtained through consecutive in vitro selection under conditions of anoxia and absence of exogenous carbohydrates. Tolerant wheat cells were used to regenerate entire plants of higher resistance to root anaerobiosis. It has been demonstrated that cells tolerance to anoxia is significantly supported by their ability to utilize exogenous nitrate. Cells tolerance established itself at the genetic level and was inherited by further generations. Apart from that, other successful attempts to increase tolerance of plants to anaerobic stress by means of stimulation of glycolysis and overexpression of genes responsible for cytokinin synthesis and programmed cell death are also discussed. The presented data proved the notion of two main strategies of plants adaptation to anaerobic stress proposed earlier on the base of fundamental studies.

[The priority contribution of academician A.L. Kursanov's scientific school to the study of oxygen metabolism and anaerobiosis in plants]. / Prioritetnye raboty nauchnoi shkoly akademika A. L. Kursanova v issledovanii kislorodnogo obmena i anaérobioza rastenii.

The biographical data on scientific activity of Academician A.L. Kursanov are presented. The contribution of A.L. Kursanov and his school to study of oxygen metabolism and plants anaerobiosis is reviewed. Special attention is given to the works on plant respiration, biosynthesis of endogenous water within plants and animals, mechanism of vitamin A biosynthesis and the metabolism of intracellular water studied with 18O methods. The important works of A.L. Kursanov's school that played an essential role in establishing the new brunch of science at the interface of physiology, biochemistry and ecology of plants, focused on the plant anaerobiosis theory are considered in details.

Blocking of anaerobic protein synthesis destabilizes dramatically plant mitochondrial membrane ultrastructure.

To elucidate the role of "anaerobic proteins" synthesized in plant cell under anoxia, the synthesis of these proteins was inhibited in rice (Oryza sativa L.) coleoptiles and leaves by cycloheximide in the course of their anaerobic incubation. Electron microscopic investigations demonstrated that the blockade of protein synthesis destabilized dramatically mitochondrial membrane fine structure. Data obtained testify to significant role of anoxic stress proteins in the plant cell adaptation and survival under anaerobic condition.

Biochemical and cytological studies of mitochondrial development in chloramphenicol-induced rice coleoptiles.

The ultrastructure and respiratory activity of mitochondria in rice coleoptile grown in the presence and in the absence of an inibitor of mitochondrial protein synthesis (chloramphenicol) have been studied. It is shown that during the first 48 h of germination a rapid development of mitochondrial cristae takes place without notable influence of chloramphenicol on biogenesis of mitochondria. But the presence of the inhibitor has a significant effect in the subsequent period (48-144 h): a gradual and almost complete reduction of mitochondrial cristae is observed. These unusual "noncristate" mitochondria, although greatly lacking cytochrome oxidase, have a high respiratory activity. The respiration of "noncristate" mitochondria is resistant to KCN. It is supposed that chloramphenicol-induced rice coleoptile can be used as a new convenient object for studies of the nature of alternative oxidase as well as the biogenesis of mitochondria with cyanide-insensitive respiration.