ABSTRACT
Transformation of a cell leading to transformed plants is a complex process. For a systematic evaluation, cell transformation has been divided into five biochemical steps: uptake, integration, replication, expression, and transmission. The fascinating field of genetic engineering of plant cells had an unusual beginning. The initial claims of genetic transformation of plants or cells are not accepted by the scientific community and are only of historical importance. Instead of using whole bacterial DNA, an attempt was made to transform plant cells with phage DNA. Due to the absence of a cell wall, a protoplast is considered an ideal system for cell transformation. Also, protoplasts, being free cells, can be easily cloned without contamination. Protoplasts from a number of plants have been shown to take up free DNA, homologous or heterologous, by different groups of workers.
