Genetically Transformed Plant Roots as a Model for Studying Specific Metabolism and Symbiotic Contacts of the Root System

Abstract

Genetic transformation of plants mediated by Ri plasmid of Agrobacterium rhizogenes occupies a special place in plant cell engineering, since this technique based on a natural phenomenon allows cultivation of separately growing roots on hormone-free media. Application of wild-type unmodified agrobacterial strains allows us to obtain root cultures capable of long-term growth in vitro due to an increased sensitivity of the cells to auxins while other biochemical properties remain unaltered. A collection of pRi T-DNA transformed roots of certain dicotyledons was constructed; some strains of it are used to study synthesis of secondary metabolites in root cells. The in vitro cultivated roots could synthesize root-specific metabolites, which allows their large-scale application for biotechnological production of ecologically pure crude drugs. Cocultivation of pRi T-DNA transformed roots with arbuscular mycorrhizal fungi makes possible vital study of all stages of obligate symbiont development and interaction with plant roots. Mixed axenic culture of AM fungi and pRi T-DNA transformed plants can be used to construct a collection of the most valuable endomycorrhizal fungal species and to produce considerable quantities of homogeneous fungal inoculums.