Direct DNA-Transfer Technologies

Direct DNA-Transfer Technologies

Direct DNA-transfer Technologies
Most monocotyledons like cereals and sugarcane are not amenable to Agrobacterium technology because they are resistant to infection by the bacterium. Alternative technologies are being developed which include the introduction of foreign DNA into plant protoplasts mediated by polyethylene glycol and poly-L-ornithine, electroporation (use of electric current), calcium phosphate coprecipitation, liposome fusion, microinjection and particle bombardment. Regeneration of plants from transformed protoplasts is labour intensive and subject to the possibility of development of somoclonal variations.

The use of 'microprojectiles' or 'particle bombardment' is a procedure for delivering foreign DNA into plant cells. The technique involves coating small gold or tungsten beads with plasmid DNA and propelling the beads to intact cells, embryos or differentiated tissues using high velocity particle , guns' or electrical discharges. This technique has been useful in delivering DNA into the nucleus and mitochondria of yeast, nucleus and chloroplasts of chlamydomonas, epidermal tissues of Allium cepa and suspension cultures of maize. A major limitation of this technology arises from the paucity in the number of particle guns available and the high cost in building them.

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