What organelle serves to protect a cell against plasmolysis?

Can't think of any. A plant cell immersed into a  a hypertonic solution will plasmolyse. The cell wall will not prevent this ; and certainly not the cell membrane.
A leaf's waxy cuticle may protect the upper epidermal cells, however, that's not an organelle. And besides, why would a leaf be exposed to hypertonicity ?
Some unicellular organisms form a cyst (a glycoprotein) in harsh environmental conditions.But,  not sure that a protective covering is considered an organelle.
Hope someone else comes up with a better answer. If they do , I'll learn something too.