Which of the following enhances or induces fusion of protoplasts?

The technique of protoplast fusion involves the chemical PEG and Sodium nitrate. The presence of the Na+ ion induces localized realignment of the lipo-protein in the membrane which in turn allows fusion to occur when two such regions come into contact. PEG solutions induce tight adhesion of protoplasts owing to electrostatic forces. The presence of cations, such as Ca2+, in the PEG solution, enhances adhesion since the calcium ion may form a molecular bridge between the negatively polarized PEG molecule and the protein of the membrane. Water is also withdrawn from the protoplast by PEG, thus reducing the turgidity of the system and allowing closer packing of protoplasts. This dramatic disruption, and possible reversal, of the charge properties of the membrane after removal of PEG, leads to membrane fusion. IAA, kinetin and gibberellins are plant growth regulators that are involved in the growth and differentiation of cells.