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Lipid polymers accumulate in the epidermis and mestome sheath cell walls during low temperature development of winter rye leaves

, , , and . Protoplasma, 125 (1): 53--64 (Feb 1, 1985)
DOI: 10.1007/bf01297350

Abstract

Summary Winter rye (Secale cereale L cv. Puma) was grown at 20 °C and at 5 °C and the development of epidermal and mestome sheath cells of leaves from plants grown at both temperatures was compared by electron microscopy. At 5 °C, the cells became densely packed with cytoplasm and small vacuoles after 41 days of growth. By day 56 at 5 °C, epidermal and mestome sheath cells were small in diameter and multivacuolate with asymmetrically thickened walls. By day 76 at 5 °C, a new developmental stage had been reached in epidermal and mestome sheath cells. The cells were larger in diameter although the thickened cell walls and multivacuolate cytoplasm were still present. As epidermal and mestome sheath cell walls thickened during low temperature growth of winter rye, an increase in cuticle thickness and the deposition of a lamellar layer could be observed in epidermal and mestome sheath cells, respectively. The lipid-derived polymers from the leaves of rye plants grown at 20 °C were shown by reductive depolymerization and GC-MS analysis to be comprised of 18-hydroxy-9, 10-epoxyoctadecanoic acid (47\%) and dihydroxyhexa-decanoic acid (29\%). The leaves of plants grown at 5 °C had two to four times as much lipid-derived polymeric material as those grown at 20 °C and the proportion of the major monomer, 18-hydroxy-9,10-epoxyoctadecanoic acid, increased to 73\% of the polymeric material. Physical isolation of both epidermal tissue and vascular bundles followed by GC-MS analysis of the monomeric components released by reduction of the respective lipid polymers showed that 18-hydroxy-9,10 epoxyoctadecanoic acid was the major monomer in the polymer of both the epidermis and the mestome sheaths. The presence of this epoxide monomer in both the cuticles and mestome sheath cell walls of rye leaves was confirmed and visualized by using an epoxide-specific staining reaction.

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