Cell Wall Deposits in Winter Rye Secale cereale L. 'Puma' during Cold Acclimation

Leaves harvested from unhardened and cold-hardened rye (Secale cereale L. 'Puma') were examined by electron microscopy. Upon cold acclimation,m mestome sheath cell walls were thickened asymmetrically toward the vascular bundle, while epidermal cell walls were thickened asymmetrically toward the leaf surface. Cell wall deposits were osmiophilic and lamellar in structure. These characteristics suggest deposition of lipid polymers. Epicuticular waxes also increased in thickness and changed from a rodlike to a platelet-like structure upon cold acclimation. Thickening of the epidermasl and mestome sheath cell walls during cold acclimation is thought to decrease injury caused by freezing or desiccation.