In producing transgenic plants, cells called protoplasts are often used. Protoplasts are plant cells from which the cell wall has been removed. Why would the cell wall need to be removed?

Plant cell walls often serves as protective coat for plant cells and tissues but could also serves as a reservoir that harbours microrganism that could lead to contamination or infection in plant.

Removal of cell walls can reduce the risk of infection also plants derived from protoplasm can be modified to give a desirable traits because DNA can be directly introduce. it doesn't require any segregation or recombination that could mix up the gene hence you get what you produce. A somaclonal plant can be developed from protoplast also callus.