Use of ri-mediated transformation for production of transgenic plants

Abstract

Agrobacterium rhizogenes-mediated transformation has been used to obtain transgenic plants in 89 different taxa, representing 79 species from 55 genera and 27 families. A diverse range of dicotyledonous plant families is represented, including one Gymnosperm family. In addition to the Ri plasmid, over half these plants have been transformed with foreign genes, including agronomically useful traits. Plants regenerated from hairy roots often show altered plant morphology such as dwarfing, increased rooting, altered flowering, wrinkled leaves and/or increased branching due to rol gene expression. These altered phenotypic features can have potential applications for plant improvement especially in the horticultural industry where such morphological alterations may be desirable. Use of A. rhizogenes and rol gene transformation has tremendous potential for genetic manipulation of plants and has been of particular benefit for improvement of ornamental and woody plants.

Intragenic vectors for gene transfer without foreign DNA

“…The tumour-inducing and hairy root-inducing genes encoded by the T-DNA of Ti and Ri plasmids are well known to prevent the regeneration of plants or result in plants with abnormal phenotype (Grant et al 1991;Christey 2001). A key step toward Agrobacterium-mediated gene transfer to plants was the development of ''disarmed'' Agrobacterium strains through either the removal of the genes responsible for tumour formation or the complete removal of the T-DNA.…”

Agrobacterium rhizogenes mediated genetic transformation resulting in hairy root formation is enhanced by ultrasonication and acetosyringone treatment

“…Various plant species differ greatly in their susceptibility to infection by Agrobacterium rhizogenes, Agrobacterium tumefaciens and other bacterial species which are capable of gene transfer to plants (Broothaerts et al 2005). Many reports suggest the use of Agrobacterium rhizogenes for expression of the rol genes and also to deliver foreign genes to susceptible plants (Christey, 2001). The hairy root harbours the T-DNA segment of Ri-plasmid within its nuclear genomes (Chilton et al 1982).…”

Iridoid and phenylethanoid glycoside production and phenotypical changes in plants regenerated from hairy roots of Rehmannia glutinosa Libosch.

“…Further improvement in the metabolite production could be provided by the regeneration of whole plants from high-producing hairy root lines. According to Christey (2001) transgenic plants have been obtained after A. rhizogenes-mediated transformation of 89 different taxa, representing more than 79 plant species, and more transformed plant taxa, e.g. Plumbago indica (Gangopadhyay et al 2010) or Tylophora indica (Chaudhuri et al 2006) demonstrate higher level of secondary metabolites than untransformed plants.…”