Panchuk I. Expression patterns of genes coding for antioxidant enzymes and chaperone proteins during plant development and under stress.

Object of the research: Molecular organization, regulation of expression and functional specialization of stress genes and complementation of protective proteins in plants. The aim of the work: to clarify the reasons of stress genes/proteins polymorphism and to elucidate molecular mechanisms of expression regulation during ontogenesis and under abiotic stress treatment (increased temperature, accumulation of heavy metal ions). Methods: molecular, biotechnological, biochemical, immunological, histochemical, bioinformatics, mathematical statistics. Regulation of expression of Арх, Cat and sHsp genes of tobacco and Arabidopsis was investigated. For the first time 11 sHsp genes of tobacco were cloned and sequenced. These genes are expressed at mRNA and protein levels upon normal temperature during pollen development. A HSF-dependent expression of Apx1 and Apx2 genes under heat stress was found. An expression pattern of the Apx2 gene indicates that this enzyme is a non-chaperone heat shock protein. The heat-dependent induction of the Apx2 promoter is tissue-specific. Impaired redox balance in Arabidopsis leaves caused by increased copper ion concentrations results in elevated Apx5 and Apx6 gene expression, whereas high cadmium increases Apx1, Apx4 and tApx expression. Knock-out mutants with impaired expression of catalase isoforms show a reorganization of their antioxidant system at enzymatic and non-enzymatic level, which provides an effective compensation of the given defect. The polymorphism of the stress genes/enzymes is crucial for providing the reliability, flexibility and selectivity of stress defence system in the plant cell. Area of use: genetics, molecular biology, plant physiology.