Plasmolytic behavior of the donor cell may affect protoplast response

Protoplast donor tissues (leaves of shoots in culture) from a herbaceous plant ( Solanum etuberosum ) and two woody species ( Populus alba × P. grandidentata cv. Crandon and Betula platyphylla szechuanica ) were compared during plasmolysis in a range of osmotic agents and potentials. Cells from both Solanum and Populus , species proven to be amenable to protoplast division and regeneration, plasmolyzed readily at higher osmotic potentials than cells from Betula , a species recalcitrant to prolonged culture after protoplast isolation. Betula leaf mesophyll cells exhibited persistent membrane-to-wall attachments and many failed to plasmolyze even under extreme osmolarity. Although their leaves exhibited similar photosynthetic rates, photosynthetic capacity was lost from Betula protoplasts upon isolation, and retained by Solanum protoplasts. Differential stress after isolation was not detectable through vital staining, but only Solanum and Populus gave both high protoplast yields and high plating efficiencies in continued culture.