Dear Dayang,

Success of all transformation investigations primarily rely on the apt regeneration protocol. In case of pulses like mung bean, chickpea etc., better regeneration protocols are achieved with the embryonal axis (usually by decapitating apex) with one attached cotyledon (if you wish, please download chickpea transformation publications from my ResearchGate site). In case of mung bean epicotyl and hypocotyl primordial seems to have good potential to regenerate. Mosaic pattern (which you have referred) is often seen in culture vessels itself both during routine regeneration as well as transformation. Please go ahead and use whatever is an ideal explant for regeneration for your transformation studies. 

Hi Dayang,

When you said "Mosaic', did you mean 'chimera'? Chimera can occur during plant genetic transformation, for different plant species and at any tissue you use as explants. The transformed cells can 'protect' the surrounding 'untransformed' cells under antibiotic selection. If your transgenic shoots (for example) are derived from these both types of cells, you can get chimeric plants. 

See attached paper for how to reduce chimera from plant transformation.

Paper title: "Effective Reduction of Chimeric Tissue in Transgenics for the Stable Genetic Transformation of Lesquerella fendleri"

Direct transfer of alien gene by electroporation into zygotic embryo cultures should be good with reduced mosaicism in transgenics.